Closer to home you can get similar things when you grind metals for instance. The sparks are at extremely high temperatures, but won't typically start fires or cause burns (it depends) because they're just too small to impart much actual energy to anything they touch.
You only get fire risks when the things they touch are themselves tiny (like dust), so they're unable to absorb and spread the heat.
A similar thing happens when you bake with tinfoil. The foil will be at like 350 F, but you can still touch it basically immediately if you're willing to gamble that nothing with thermal mass is stuck to it where you can't see. It just doesn't have enough thermal mass on its own to burn you, but if there's a good-sized glob of cheese or water or something on the other side you can really be in for a nasty surprise.
Tin foil and aluminum foil do have generally different properties. For instance, tin foil can disrupt mind control and aluminum foil can't, and corrosion effects are likely at least different. But any thin metal foil isn't going to be able to hold much heat, because there's just not that much material.
"The thermal conductivity of aluminum is 237 W/mK, and that of tin is only 66.6 W/mK, so the thermal conductivity of aluminum foil is much better than that of tin foil. Due to its high thermal conductivity, aluminum foil is often used in cooking, for example, to wrap food to promote even heating and grilling, and to make heat sinks to facilitate rapid heat conduction and cooling."
Not at all. Just doing my part to point out, whenever it's topical, that tin foil hats work and aluminum foil hats don't. There's a reason they want you to call aluminum foil by the wrong name.
Mind control waves are pure magnetic fields as opposed to traditional EM waves. So although aluminum can act as a Faraday cage, its not a magnetic shield and hence not capable of stopping mind control.
Alec Steele (youtube blacksmith) installed a particulate filter into his grinding room before he branched off into exotic metals. He also started keeping his shop floor a lot cleaner.
Both because you probably shouldn't breathe that shit in, and also magnesium and titanium dust are very enthusiastic about combusting. Everyone knows about magnesium but nobody knows titanium is almost as surly.
True, dust of combustable stuff can be very dangerous if it accumulates, and the things that will combust as dust are not terribly predictable. Eg, flour is a _serious_ explosion risk if it's mixed with the right amount of air.
Almost ANY small particle in a light-density air suspension (dust cloud) will ignite. Certainly anything that oxidizes is prone to going WHOOF! around flames.
This includes non-dairy creamers, paint spray, insecticide sprays (canned or pumped), and sawdust tossed over a fire.
I think similar of radiant heaters. The heating elements are clearly very hot, glowing even, but you never reach equilibrium with it: your leg will not get that hot. This is because your leg is cooled by conduction and convection (which is basically conduction again) and possibly a little evaporation.
Yeah, radiative cooling/heating is actually super slow compared to any other type. This is why it's so hard to cool anything in space, it's your only option and it kind of sucks at its job.
Wouldn't the other option be ejecting heat "ballast"?
I'm sure that would lead to other issues (sure, ejecting it would move you, but you could just always eject it in the opposite of the direction you want to go, which is how spaceships work in the first place), but what if you had super-cooled ice in a thermos-like enclosure, and as you needed to cool you pulled some out, let it melt, then vaporized it, then superheated the steam, then vented that out the back?
I think you could do that, but mass in space is kind of hard to come by. If it wasn't (like if you're on the moon) you could just use the mass for conduction anyway. If you have to ship it up and consume it like that, that's expensive and limiting.
I'm not sure you can practically superheat the ballast without just causing more heat that you have to deal with. Maybe a heat pump works? Something about that feels vaguely wrong.
If you're about to generate super high temperatures (via a heat pump), might as well use a radiator again. Radiative heat transfer rate scales with temperature to the fourth power. Any such system requires energy, however.
The other thing that helps you is that you're made mostly of water, which is one of the substances with the highest heat capacity. So it's hard to heat up or cool.
That's actually most of space. Space is a very hot environment, especially where we are so close to the sun. Think about it. When you stand outside in the sun you heat up. All that heat is coming from the sun. But a lot of it was filtered by the atmosphere, so if you're in space near earth it will be hotter than standing at the equator on a sunny day, in terms of radiation.
Then there's the fact that heat is very difficult to get rid of when in space. The ISS's radiators are much bigger than its solar panels. If you wanted to have a very-long eva spacesuit you'd have to have radiators much bigger than your body hanging off of it. Short evas are handled by starting the eva with cold liquids in the suit and letting them heat up.
All of the mockups of starships going to Mars mostly fail to represent where they're going to put the radiators to get rid of all the excess heat.
> If you wanted to have a very-long eva spacesuit you'd have to have radiators much bigger than your body hanging off of it.
I was curious about this! The Extravehicular Mobility Units on the ISS have 8 hours of life support running on 1.42 kg of LiOH. That releases ~2 kJ per gram used, so .092 watts.
The 390 Wh battery puts out an average of 50 watts.
And the human is putting out at minimum 100 watts with bursts of 200+.
Long term it's probably reasonable to need at least 200 watts of heat rejection. That's about a square meter of most radiator, but it needs to be facing away from the station. You could put zones on the front/back and swap them depending on direction, as long as you aren't inside an enclosed but evacuated area, like between the Hubble and the Shuttle. The human body has a surface area of roughly 2 m^2 so its definitely not enough to handle it- half of that area is on your arms or between your legs and will just be radiating onto itself.
It's also not very feasible to have a sail-sized radiator floating around you. You'd definitely need a more effective radiator- something that absorbs all your heat and glows red hot to dump all that energy.
Or, evaporative cooling for spacewalks. Water heat of evaporation at 25°C is 678 Wh/kg, so 200W of heat is about 0.3 kg per hour. Quite manageable!
EDIT: Apparently the Apollo suits did this. An interesting detail is that they used sublimation (evaporating ice directly to vapor), because I suppose that's a lot more practical to exchange the heat.
Reminds me of the book Saturn Run, by John Sanford - which has a lot of effort put into the technology and radiation of heat in their space ship. Fun science fiction book.
Per wiki: radiators reject 100-350 watts per m^2 and weigh ~12 kg per m^2. Not unlikely you would need 10x as much radiator as server. You need about as much area for radiators as you do for solar panels, but radiators are much heavier.
That also makes nuclear totally infeasible- since turbines are inefficient you'd need 2.5x as many radiators to reject waste heat. Solar would be much lighter.
Nuclear power is very feasible in space. Perhaps you're overlooking that radiated power scales with the quartic of absolute temperature (T⁴); it's not difficult at all to radiate heat from a hot object, as it is for a room-temperature one.
(How hot? I won't quote a number, but space nuclear reactors are generally engineered around molten metals).
Yeah, fair to say its feasible. ROSA on the ISS produces 240 W/m^2 and weighs 4 kg/m^2.
The S6W reactor in the seawolf submarines run at ~300 C and produce 177 MW waste heat for 43 MWe. If the radiators are 12 kg/m^2 and reject 16x as much heat (call it 3600 W/m^2) then you can produce 875 watts of electricity per m^2 and 290 watts at the same weight as the solar panels. Water coolant at 300 C also needs to be pressurized to 2000+ PSI, which would require a much heavier radiator, and the weight of the reactor, shielding, turbines and coolant makes it very hard to believe it could ever be better than solar panels, but it isn't infeasible.
Plus, liquid metal reactors can run at ~600 C and reject 5x as much heat per unit area. They have their own problems: it would be extremely difficult to re-liquify a lead-bismuth mix if the reactor is ever shut off. I'm also not particularly convinced that radiators running at higher temperatures wouldn't be far heavier, but for a sufficiently large station it would be an obvious choice.
It goes up to 1,344 °C with Li, I think—it's a very different engineering space from the stuff on Earth.
The Soviet ones used K (or maybe NaK eutectic); there's a ring of potassium metal dust around the Earth people track by radar (highly reflective)—a remnant from one of them exploding.
The idea is not completely without merit. In gravity less environment, you can have much bigger and much thinner structure possible than on Earth.
Also the radiated heat from the Sun won't have much effect if the heat sink panels are facing perpendicular to the sun with two sides pointing sideway to deep space to radiate away the heat.
But boiling water is just a few hundred Kelvin, this is tens of thousands. Would EVA spacesuits be able to radiate that much away if it was really that hot but for the atmosphere absorbing some?
I know it is much hotter, but that's way way hotter and they only find it at a "wall" way farther out.
This is more the temperature of the solar wind, dwarfing the steady state temperature you'd reach from the photonic solar radiation at any distance. The Sun's blackbody varies from like 5000K to 7000K, you won't see objects heated in the solar system heated higher than that even with full reflectors covering the field of view of the rear with more sun and being near the surface of the sun, other than a tiny amount higher from stellar wind, tidal friction, or nuclear radiation from the object's own material I don't think.
> Would EVA spacesuits be able to radiate that much away if it was really that hot but for the atmosphere absorbing some?
Yes! The tiny number of particles are moving really fast, but there are very few of them. We are talking about vacuum that is less than 10^-17 torr. A thermos is about 10^-4 torr. The LHC only gets down to 10^-10 torr. At those pressures you can lower the temperature of a kilometer cube by 10 thousand kelvin by raising the temperature of a cubic centimeter of water by 1 kelvin. There is very little thermal mass in such a vacuum which is why temperature can swing to such wild levels.
This is also why spacecraft have to reject heat purely using radiation. Typically you heat up a panel with a lot of surface area using a heat pump and dump the energy into space as infrared. Some cooling paints on roofing do this at night which is kind of neat.
Solar radiation is roughly 1 kilowatt per square meter. Human beings generate about 0.1 kilowatts. A good suit will try to reject as much of that kilowatt as possible. Also your dark side will radiate heat but the temperature differential is much lower.
Suits are insulating for a reason. You want to prevent heating on the sun side and prevent too much cooling on the space side. Your body is essentially encapsulated in a giant thermos.
Cooling is achieved using a recirculating cold water system that is good for a few hours of body heat. Water is initially cooled by the primary life support system of the spacecraft before an EVA. Pretty much it starts off pretty cold and slowly over time comes up to your body heat. Recent designs use evaporative cooling to re-cool the water.
Absorbed light too but that's a bit easier to deal with and is why most things are white or reflective on the outside of anything in space that's not intentionally trying to absorb heat.
At this low density, temperature is very different from what you are used to experiencing. You have to work through a heat flux balance to really get a grasp of it.
Temperature is just the heat of particles moving. In the extreme case of a handful of N2 molecules moving at 1% the speed of light, it has a temperature of something like 9 billion Kelvin. But it's not going to heat you up if it hits you.
Even at low density, if it were a large volume, solid objects would heat up to that ambient temp. But this one is a minor volume and you would still be radiating it away much faster and not reach anywhere near the ambient temperature. In the middle of a large volume thoigh, you'd get too much incoming thermal radiation from particles within the volume and not be able to shed heat anywhere through radiation.
Lack of radiators is endemic in sci-fi. All those cool starships and torch rockets would bake their crews and then melt.
I didn't like the Avatar films except for the starships, which are among the more physically realistic in construction including massive radiators. They'd probably need to be even bigger though IRL if you're talking about something loony like an antimatter rocket.
> Think about it. When you stand outside in the sun you heat up. All that heat is coming from the sun. But a lot of it was filtered by the atmosphere, so if you're in space near earth it will be hotter than standing at the equator on a sunny day, in terms of radiation.
I think you’re missing the key point - heat transfer. The reason we feel hot at the beach is not solely because of heat we absorb directly from solar energy. Some of the heat we feel is the lack of cooling because the surrounding air is warm, and our bodies cannot reject heat into it as easily as we can into air that is cool. And some is from heat reflecting up from the sand.
Theres a heat wave across much of the US right now. Even when the sun goes down it will still be hot. People will still be sweating , doing nothing, sitting on their porches. Because the air and the surrounding environment has absorbed the sun’s heat all day and is storing it.
That’s what you’re neglecting in your analysis of space.
Okay this may sound silly but what about a solar powered ac for cooling? Like solar radiation is 6000K right, so if you used that to pump your waste heat into say a 1000K radiator (aimed away from the sun obviously) I'm thinking it might give you plenty of negentropy but also radiate away heat at a decent pace.
Skip the Sun! There's an "atmospheric window" in the IR. If you make a material that emits/absorbs (they're reversible) only in that region, and don't expose it to the Sun, then it will cool down to the temperature of space, roughly 3K or -270°C. In practice, it won't cool down anywhere near that much. It'll steal energy from it's surroundings due to conduction/convection, and the amount of energy that's actually radiated in this band by a slightly below room temperature material is pretty minimal. Still neat, entirely passive cooling by radiating to space!
Radiative heat transfer is proportional to T^4. If your suit is 300 K(80F), bumping the temperature up by 100 C lets you radiate 3.16x as much heat from the same area.
> An absorption refrigerator is a refrigerator that uses a heat source to provide the energy needed to drive the cooling process. Solar energy, burning a fossil fuel, waste heat from factories, and district heating systems are examples of heat sources that can be used. An absorption refrigerator uses two coolants: the first coolant performs evaporative cooling and then is absorbed into the second coolant; heat is needed to reset the two coolants to their initial states.
> Fishermen in the village of Maruata, which is located on the Mexican Pacific coast 18 degrees north of the equator, have no electricity. But for the past 16 years they have been able to store their fish on ice: Seven ice makers, powered by nothing but the scorching sun, churn out a half ton of ice every day.
It literally doesn't matter what your refrigeration process is. You have to "reject" the heat energy at some point. In space, you can only do that with large radiators.
There is no physical process that turns energy into cold. All "cooling" processes are just a way of extracting heat from a closed space and rejecting it to a different space. You cannot destroy heat, only move it. That's fundamental to the universe. You cannot destroy energy, only transform it.
Neither link is a rebuttal of that. An absorption refrigerator still has to reject the pumped heat somewhere else. Those people making ice with solar energy are still rejecting at minimum the ~334kj/kg to the environment.
An absorption refrigerator does not absorb heat, it's called that because you are taking advantage of some energy configurations that occur when one fluid absorbs another. The action of pumping heat is the same.
The question was 'what about a solar powered ac for cooling?', yes?
Giant radiators don't make ice.
The proposed method of pumping heat into someplace hot to make it hotter doesn't work. But there area definitely ways to do solar powered ac for cooling.
Since this discussion is still active, I think hwillis was the only one that got my idea. Pumping heat into the radiators will make them hotter then they would be by just passive conduction, and then the T^4 radiation scaling means that the radiators will start radiating a lot, i.e. a lot of heat will be sent into deep space.
The plasma inside arc lamps (e.g. xenon headlights) are somewhere around 6,000-10,000 K.
Then there are things like fusion reactors where the temperature is in the millions of degrees and the whole point of the design is to keep the heat in.
Edit: although interestingly in an electric arc, often the electrons have a higher kinetic energy (temperature) than the heavier ions and atoms in the plasma. It's a highly non-equilibrium situation. That plays into your "high temperature, slow transfer" thing quite nicely: even the atoms within the plasma don't reach the full temperature of the electrons.
What is the temperature on either side of this “wall”? My mental model here, which is probably incorrect, is that the “temperature” on the outside of the wall could be higher but the density is much lower, thus even less heat transfer going on (but, still, high energy particles that can hit you, registering a high temperature). I get all kinds of mixed up regarding the difference between heat transfer and measured temperature.
It's one of the reasons I love Oxygen Not Included so much. That game's materials have both Thermal Conductivity and Specific Heat as stats, and density plays into it as well.
I thought the same thing too. It is very hot, without having very much heat - in a way.
The Parker Solar probe encounters a similar situation where it has to handle high amounts of direct radiation, but the latent/ambient environment is full of incredibly hot particles at very low density (because they are so hot) which means it isn't that hard to make the probe survive it.
See also: the exosphere. Helium and Hydrogen in Earth's atmosphere float up above the others and form a layer which hangs out around 1000 °C. Despite the high temperature, you'd probably get hypothermia if you stayed too long in the shade at that altitude (supposing the low pressure didn't get you first).
Temperature, it would seem, is an idea that would only have developed at the bottom of a gravity well.
I often think about how cold our lifeforms on earth are, relative to temperatures of things in the universe. 0 Kelvin is theoretical lowest possible temp, quasars are apparently > 10 trillion Kelvin (10,000,000,000,000K), yet all life we know of is between what, 250K and 400K?
Basically it's because the relevant structures are somewhat fragile. Matt Strassler has a good post about "why does everything we care about move so slowly compared to the cosmic speed limit?" (https://profmattstrassler.com/2024/10/03/why-is-the-speed-of...), and the answer is, it's because we're made of atoms, atoms are held together by the electromagenetic force, and that's only so strong, if things moved way faster then collisions would tear atoms apart. But of course life is dependent not only on atoms, but also on electromagnetic bonds much weaker than the ones that hold atoms together. So this limits how hot it can get.
If you’ll excuse a bit of trivia: SI units named after people are not capitalized. So we have newton, joule, weber, kelvin, named after Newton, Joule, Weber, and Kelvin. (But their abbreviations are capitalized: N, J, Wb, K.)
Correct. The parent of your post should have written "10 trillion kelvins", "10 terakelvins", or "10 TK". The article wrote "Temperatures there reach an astonishing 30,000-50,000 kelvin" instead of "kelvins" (or better yet, 30–50 kK).
The only exception regarding capitalization is that the person Celsius is capitalized in the multi-word unit "degree(s) Celsius", and the pluralization is on "degree".
Good point about pluralization. I tend to be confused about that because we don't pluralize units in Norwegian (except the equivalent of degrees). But confusingly, in English, you sometimes see people trying to pluralize the abbreviations, such as kgs for kilograms. Or (even worse) ms for meters. That way madness lies.
I was aware of this, but you putting it into numerical terms rather than an intuitive understanding is really cool. Even a small fire is dramatically hotter than life, yet nothing in comparison to what happens outside of our relatively frozen little bubble here on Earth
Well, lifeforms on earth are all pretty dependent on being water based, and water in the liquid state specifically. Maybe there is a possibility of exotic life based on some other types of chemistry and/or phases of matter. But the fact that earth happened to form in this particular goldilocks zone for water-based life is probably why that's the only life we can see for now.
I have to mention Robert L. Forward’s Dragon Egg—it explores life on a white dwarf with nuclear reactions instead of chemical ones. Not the best book, IMHO, but a fun thought to entertain.
Probably true, in that if you try to travel interstellar distances you'll going to have to deal with very hot particles hitting your ship on occasion. If you travel slowly the more time you're going to be spend getting hit by high energy particles. If you try to travel quickly you're going to have to deal with more relatively high energy particles. It's potentially enough to make interstellar travel impossible.
Systems we built in the 1970s were able to easily pass through this though. Which doesn't seem to indicate that it would make interstellar travel impossible.
Systems from the 1970s travel at, by interstellar standards, agonizingly slow speeds. The voyagers will be exposed to hard radiation for thousands of years before they get anywhere interesting. They will not survive.
Not sure exactly why you're responding to me. The comment I was responding to was talking about the hot particles that would be encountered, and that their existence could preclude future interstellar missions.
What level of "hard radiation" are they now getting bombarded by that we will be unable to shield systems from in far future interstellar space travel?
I'm saying the Voyager probes don't make a counter example to interstellar travel being impossible. That's still very much an open question. We might be able to develop adequate shielding to protect spacecraft from radiation over mildly geologic timespans, but we might not. I'm certain it won't be as easy as you seem to think it is.
(Unless you count slinging a dead pile of former computers through a distant star system as successful interstellar travel, but that's not what most people are interested in.)
The Fermi paradox doesn't require travel, though. The lack of any sign of life at all is still surprising (no radio signals, etc), even if we knew it couldn't physically come here.
It would take a lot of power to send even a radio signal that could be picked out from the noise at a few light years. Add a requirement for that signal to be more or less continuous over geologic timescales - we’ve only been able to emit and detect these for ~100 years - and my personal surprise diminishes rapidly. Huge distances in time and space with human-level technology make detection highly unlikely.
Yes, and I would add my favorite hypothesis to the paradox, an anthropocentric assumption theory of self importance... or let's call it an anthropocentric bias:
Humans tend to define intelligence, life, and communication based on our own structure -carbon-based biology, electromagnetic signaling, language, symbolic thought, etc. This narrows the scope of our search.
We assume other civilizations want to communicate, would use similar media (radio, light, mathematics), and would send signals we could interpret. This ignores other potential modalities (quantum, neutrino, gravitational, exotic matter, etc.) or entirely non-signal-based forms of interaction.
We may not even recognize signs of intelligent activity if they don't resemble our expectations, ie entire civilizations could exist in forms of computation or energy we can’t perceive.
We assume ET intelligences are aligned with our timeframe or curiosity. Maybe they don’t care to communicate, see us as trivial, or operate on million-year attention spans.
It may reflect less the silence of the cosmos and more the limits of our understanding, especially the assumption that we're capable of detecting or interpreting intelligence beyond Earth. A epistemic humility, or rather our lack of it.
Nobody would be communicating with neutrinos or gravitational energy. EM radiation is way easier to emit and detect, and at cosmic distances they all scale exactly identically (inverse square law). The other things you mentioned are mostly sci-fi inventions and there’s nothing in known or unknown physics that would hint towards them being plausible communication media.
It’s not about being shortsighted, it’s about everyone being constrained by the same laws of physics. Our models, however imperfect, are still unreasonably good.
The counter argument is that even if civilizations exist with all the properties you described, given the vastness of space, there should be another civilization that pattern matches to us.
Sure! All the hypothesis in the Fermi paradox deal ultimately with calibrating our expectations of making contact, not with denying the existence of "STEM-enabled" species like us yearning for an alien encounter.
There's epistemic humility, then there's indulging in unfalsifiable fantasies in the name of not ruling anything out.
> Humans tend to define intelligence, life, and communication based on our own structure -carbon-based biology, electromagnetic signaling, language, symbolic thought, etc.
I would posit that none of these properties are coincidences, and are in fact likely to evolve convergently in most if not all circumstances hospitable to life. In particular I very much expect ET life to be carbon based; I don't believe there's a true viable alternative outside scifi (hint: silicon ain't it).
> entire civilizations could exist in forms of computation or energy we can’t perceive.
Could they? Really? There aren't that many gaps in the Standard Model. The aliens could be made of dark matter, I guess, and remain forever undetectable, but that's not to far off believing in invisible fairy kingdoms. And it still wouldn't explain why the baryonic sector is so devoid of detectable life. Ethereal undetectable aliens don't mean regular ones can't also exist.
> Maybe they don’t care to communicate, see us as trivial, or operate on million-year attention spans.
This one I'll grant (sort of: what's the evolutionary path toward such entities arising?), but it's still weird that we haven't seen any sign at all of them. These entities live on million-year timescales but have no visible effect on their surroundings? Why?
And more importantly, why is that the only thing that happens? Because if it isn't the only thing, then the question remains of why can't we see anything else?
Radio signals aren't the only sign. I'd really love to see some sign of megastructure engineering, but even detecting O2 in an extraterrestrial atmosphere would be huge.
It's not a new idea. The posted article is just about Voyager apparently observing the phenomena more closely. Voyager 1 had already reached the termination shock of the heliosphere in 2004 and Voyager 2 in 2007. The heliosphere containing a heliosheath, past the boundary of the termination shock, composed of compressed superhot solar winds had been hypothesized, due to the compression of the solar winds that begins at the termination shock.
Reading the article, the wall is referring to the heliopause, which is the boundary past the heliosheath. Also, it looks like both voyagers traveled past this over a decade ago.
It's great that we're still getting data from these two probes 50 years later but it absolutely sucks that these are the only 2 probes we have out there. How long can they keep running, another 5 or 10 years max? It's already considered an engineering miracle that they are still going.
What of people growing up 10, 20, 30 years from now? They'll be taught in school about stuff from Voyager and then told 'and that was what we learned in the golden age of space exploration, which ended long before you were born because we couldn't be bothered to keep at it.' Having grown up in the 70s, I feel somewhat betrayed that we just just gave up on doing moon stuff, rendering a whole generation's aspirations on space exploration into a lie. The claims that 'there is nothing more to discover up/out there' is nonsense, much like the claims that 'chips can't be made any smaller' that I would hear back in the 32nm period.
The lack of long-term commitment to exploratory space is a terrible waste. To be sure we have been doing some stuff in system, but if he had kept putting out deep space probes every few years with more advanced instruments we would have learned a lot of other things by now, and we would have a long-term stream of new data coming in for the future. Now arguments for launching more deep space probes are dismissed with 'it'll take decades before we get anything useful back.' Yeah, because we stopped iterating! Meantime allowing that sort of exploration to become anachronistic is one reason we are overrun with flat-earthers and other science woo even at the highest levels of government.
> How long can they keep running, another 5 or 10 years max?
NASA hopes to make it the 2030s with 1 remaining science instrument on each[0]. Currently, Voyager 1 has 3 remaining instruments (of 11) and Voyager 2 only has 2. ~2036 is the maximum cutoff, as then they will be out of range of the Deep Space Network[1].
New Horizons is being sent into the interstellar medium.
More and more deep space missions are orbiters or landers now, so there are fewer flyby missions that can double as interstellar medium missions like Voyager/Pioneer, but New Horizons is one of them.
Voyager of course took advantage of an alignment of the planets in order to perform the Grand Tour. Apparently it's 175 years before it happens again, FWIW.
I suppose an extra-solar-system probe though would simply need some gravitational slingshotting and not necessarily visit many of the outer planets. I suppose that changes the time scale.
Exploration, especially space exploration, has only ever come with military advantages. If one could interest military agencies that the exploration was in their best interests we could see a space-revival of sorts. That would only last for as long as the military advantage lasts.
This is an unfortunate reality of our society. We've only ever spent dollars in space when it was advantageous to our Department of Defense, and the military in general.
People and companies who have succeeded in space have tied their goals to overarching military objectives. It's the best way to win the space race. Make the military understand they need to do the thing you want to do.
I would say "nationalist ego" instead of military advantages. Edmund didn't bring back any new weapons from the Pole. And, for that matter, our 1960s-70s race was as much (or more) about oneupmanship than gaining real tactical advantage - although of course a lot of the experience gained supported ICBM development.
It seems they use several tools - inferring from the descriptions, they can measure and compare the data when it gets back here to determine simple things like temps.
50 years in deep space and still delivering useful specific data! Whenever I think of the Voyagers, I cannot help being amazed by the engineering efforts of the Voyager team. A true marvel of engineering that will stay unchallenged for a very long time. Most respect to the team!
Just to be clear, the computers onboard the spacecraft are programmed in assembly language--3 types of computers on each spacecraft, so 3 assembly languages.
The original ground system was mostly written in Fortran. Mission control (i.e., the thing you see on TV!) ran on IBM 360 mainframes. Offline analysis/design/development activities (e.g., developing observation sequences for planetary encounters) ran on Univac 1108 mainframes. Circa 1990, after Voyager 2's flyby of Neptune, the project began moving off the mainframes onto Unix workstations and the original Fortran software was largely replaced by new software written in C and other languages.
Fascinating that we're still getting useful science out of almost 50 year old tech. I think New Horizons is the only other probe that's expected to go interstellar.
Are the particle velocities that are being measure correlated at all? As in, flowing away from the sun or similar? I'd think that something with a well-defined "temperature" would be composed of randomly moving particles with a mean velocity of zero. I'd also be interested in the distribution of particle speeds. Would anyone one consider a collimated beam of neutrons to have a temperature?
And I wonder what the distance mean free path length is. I suppose that must be pretty large. So that the T^4 Boltzmann radiation law doesn't really apply to these ~40,000 Kelvin temperatures? Or maybe the emissivity of hard vacuum is really low? I guess I've never thought about it before.
"While not a hard edge, or a "wall" as it has sometimes been called, here both spacecraft measured temperatures of 30,000-50,000 kelvin (54,000-90,000 degrees Fahrenheit), which is why it is sometimes also referred to as a "wall of fire". The craft survived the wall as, though the particles they measured were extremely energetic, the chances of collision in this particle-sparse region of space are so low that not enough heat could be transferred to the duo."
Also, worth noting that these temperatures are not that high as far as plasmas go. This is 3-5 eV, which is firmly in the "low temperature" regime (like a fluorescent bulb).
This isn't strange at all, but rather an artifact of the nature of heat energy in a medium. Heat is the uncorrelated movement of particles that evens out to zero effective velocity. Temperature is the measure of the velocity magnitude of these individual particles. This is independent of the medium's density.
I'm just a layperson, but I'd suspect the research is sound.
I hate the telephone tag, livescience.com-type journalism. Instead, I'd love to read an abstract and methods. The research must talk about this in detail and explain how the conclusions are reached. It probably isn't too inaccessible.
I suspect that there may be many such measurements correlated between both probes taken against some other baseline signal or an observed return to the mean.
30K to 50K K? K.
It’s not clear what the range represents. Were they polling and those are max and min values they got? Was that their range of uncertainty because it’s hard to accurately measure there?
Also, I hate the ambiguity of a title that references “Voyager Spacecraft” so it’s unclear if it was one or both.
"In 1977, NASA launched the Voyager probes to study the Solar System's edge, and the interstellar medium between the stars. One by one, they both hit the "wall of fire" at the boundaries of our home system, measuring temperatures of 30,000-50,000 kelvin (54,000-90,000 degrees Fahrenheit) on their passage through it."
That paragraph is the problem. It doesn't actually explain it. Were they continuously polling temps and reached as low as 30K and as high as 50K? If the 'wall of fire' is based on temps, did they have a continuous rise? what was the temp just outside the 'wall'?
I skimmed the links that TFA provided and couldn't find the source of that figure. With rare space plasmas near shocks it's typical to have non-thermal distributions where the temperature isn't well defined. I don't think it's anything to get to excited about without having a proper article from NASA instead of IFL slop.
So it's more the temperature range uncertainty?
is that a product of the environment (and with few particles one can actually measure) or a product of the measurement apparatus?
Same reason why you can sit in a sauna with very hot air or pass your hand through a flame quickly without severe burns. Low density matter does not transfer heat very well. And space is especially devoid of matter.
There is no thermal mass. It's almost pure vacuum but the handful of particles that are out there are whizzing around at high energies that make them very hot.
Interesting to think that while it's not a concern to Voyager at its pokey 17km/second, a true interstellar ship traveling at some respectable fraction of C would compress the diffuse interstellar gasses enough to make them a potential hazard. You frequently see people saying stuff like "if we could accelerate to a high fraction of C you could get anywhere in the galaxy in a single lifetime", but it may not be so simple.
I suppose an interstellar ship that could accelerate to a notable fraction of c would also be powerful enough to leave the ecliptic and avoid this heat cloud.
Most replies are talking about the low density of the matter in that area, which is one part of the equation. The other part of the equation is radiative heat transfer. Without radiation pulling heat away, the spacecraft would asymptotically heat up to the temperature of the surrounding matter.
Radiative heat transfer, roughly speaking, tries to bring the temperature of the probe to the average temperature of all the matter that it has line of sight to -- somewhere between the temperature of the sun and the temperature of the cosmic background radiation. Since the probes are far away from the sun, this average temperature is very low.
Both effects are present everywhere. On Earth, with our dense atmosphere, conductive transfer is usually the stronger effect. In space, with extremely low density, radiative heat transfer is stronger.
The average stuff is very hot, but there's also basically no stuff out there anyway, so you won't run into enough of it to care.
Imagine that there is one venomous and aggressive snake (in a cute little survival-suit) in some random spot in Antarctica. This means "the average snake in Antarctica" is ultra-dangerous.
But there's only one, and it's almost impossible for you ever to meet, so in practical terms it's still safer than Australia. :p
Because very few hot particles ever touched the craft. The gas is so incredibly thin that Voyager largely sailed straight through the space in between molecules.
The craft survived the wall as, though the particles they measured were extremely energetic, the chances of collision in this particle-sparse region of space are so low that not enough heat could be transferred to the duo.
Temperature is a measure of the kinetic energy of a particle, so they can be both extremely hot and extremely diffuse.
It did, but I still didn't understand it. Sorry, not a physics major. And I understand that heat radiates through empty space. Sounds like it's not actually that hot where voyager is, but instead filled with random particles that are that hot.
You're mixing together temperature and heat transfer. That region is very hot, but it transfers very little heat. It's like getting hit with a blast of hot air when you open the oven. The air is hot enough to harm you, but it can't carry enough heat to actually harm you unless you stay there for a long time.
Except where Voyager is, the "air" is so thin there are like a dozens zeroes on the percentage thinner it is, so the amount of heat it carries is also divided by a similar amount.
Each particle is carrying a huge amount of heat, but it gets hit by very few particles. Earth is the inverse; each particle carries a very moderate amount of heat, but you get hit by a lot of them.
Ah yes, I turned off a bunch of Kaspersky internet security settings and I'm through. This is my work computer I forget what's running in the background sometimes.
I'm confused. The plot summary talks about an impenetrable sphere around our solar system, but also says, "The main character takes part in an expedition to a newly discovered habitable solar system with a shattered sphere." How'd the character escape from our own system?
> It is also discovered that the Nataral chose to go into a kind of suspended animation around a black hole, joining two even earlier species, to wait for the other civilizations of the universe to develop interstellar flight capabilities.
They used their interstellar flight capabilities to go wait for someone in the universe to develop interstellar flight capabilities. Checks out.
If I recall (its been 25+ years and my copy is in storage), they went there to wait for other civilisations to develop. They were truly early life and there was literally nobody else and they determined that they would be waiting for millions of years, if not billions.
I don't know if it was this book, but the 'suspended animation' was basically pushing several large stars and neutron stars close enough together that the flat space between them was inside an encompassing event horizon, and there they waited, living their lives at an extremely slow (compared to the outside universe) pace.
Is it that there is not enough mass beyond the 30k-50k Kelvin wall at the edge of the solar system to attract away things with mass that can carry thermal energy; that thermal mass clumps in the well around the edges and only wisps away, or is that a sidewall boundary of a black hole?
Where is Planet X in relation to said wall of energy density?
Said wall is only sampled by the Voyager probes with a few exit trajectories?
Does said thermal wall extend all the way around the solar system, or is it mostly on one side of the sun; is it a directional coronal wake? Is there symmetry in said thermal wall around the trajectory of the sun?
Is this better explained with SQR Superfluid Quantum Relativity?
Are there other phases of matter at those temperatures?
From the article:
> "As the heliosphere plows through interstellar space, a bow shock forms, similar to what forms as a ship plowing through the ocean
So fluidic space wind and fluidic nonlinear bow shock wakes.
Are there additional heat walls beyond (and probably also before) the first, as there are with more laminar boat wakes?
From my understanding the wall is not the Oort cloud but instead the solar winds bouncing off the exterior winds more like how the Pacific and Atlantic oceans don’t mix.
It’s very odd to think of something extremely hot but with almost no density, and therefore very little heat transfer.
Closer to home you can get similar things when you grind metals for instance. The sparks are at extremely high temperatures, but won't typically start fires or cause burns (it depends) because they're just too small to impart much actual energy to anything they touch.
You only get fire risks when the things they touch are themselves tiny (like dust), so they're unable to absorb and spread the heat.
A similar thing happens when you bake with tinfoil. The foil will be at like 350 F, but you can still touch it basically immediately if you're willing to gamble that nothing with thermal mass is stuck to it where you can't see. It just doesn't have enough thermal mass on its own to burn you, but if there's a good-sized glob of cheese or water or something on the other side you can really be in for a nasty surprise.
I wonder if actual tin foil would behave differently from the aluminum foil that we are all now using.
https://en.wikipedia.org/wiki/Tin_foil
Tin foil and aluminum foil do have generally different properties. For instance, tin foil can disrupt mind control and aluminum foil can't, and corrosion effects are likely at least different. But any thin metal foil isn't going to be able to hold much heat, because there's just not that much material.
Ooooh! I get to share my favorite Stack Exchange answer!
https://physics.stackexchange.com/a/208520/82798
The anti mind control tinfoil hat was invented in 1926 by SciFi author Julian Huxley, brother of Aldous.
I do not think that you are correct.
"The thermal conductivity of aluminum is 237 W/mK, and that of tin is only 66.6 W/mK, so the thermal conductivity of aluminum foil is much better than that of tin foil. Due to its high thermal conductivity, aluminum foil is often used in cooking, for example, to wrap food to promote even heating and grilling, and to make heat sinks to facilitate rapid heat conduction and cooling."
https://www.chalcoaluminum.com/blog/aluminum-foil-tin-foil/
If it rounds to zero, then perhaps 4x'ing it won't make a difference?
Well, heat capacity and thermal conductivity are not the same thing
That’s the part of the comment you took issue with? Lol.
The things that you can measure are science.
The things that you can't measure are... not.
> tin foil can disrupt mind control
You're not weaponizing Gell-Mann amnesia against us are you?
Not at all. Just doing my part to point out, whenever it's topical, that tin foil hats work and aluminum foil hats don't. There's a reason they want you to call aluminum foil by the wrong name.
Committed to the bit.
Kudos
Mind control waves are pure magnetic fields as opposed to traditional EM waves. So although aluminum can act as a Faraday cage, its not a magnetic shield and hence not capable of stopping mind control.
Tin foil keeps the illuminati out of your brain. That's why they cancelled it. And I have proof!
Alec Steele (youtube blacksmith) installed a particulate filter into his grinding room before he branched off into exotic metals. He also started keeping his shop floor a lot cleaner.
Both because you probably shouldn't breathe that shit in, and also magnesium and titanium dust are very enthusiastic about combusting. Everyone knows about magnesium but nobody knows titanium is almost as surly.
So am I to understand we could theoretically make tempered magnesium swords that explode when struck?
It’s a matter of surface area. You’d have to ask a chemist, this is far above my pay grade.
True, dust of combustable stuff can be very dangerous if it accumulates, and the things that will combust as dust are not terribly predictable. Eg, flour is a _serious_ explosion risk if it's mixed with the right amount of air.
> magnesium and titanium dust are very enthusiastic about combusting
Iron dust too. Make sure to keep it away from your pre-lit candles:
https://youtu.be/vZ3Pi1QBAlQ
Don't let your rust and aluminum filings mix too well either. It's bad.
OK, this has gotten silly.
Almost ANY small particle in a light-density air suspension (dust cloud) will ignite. Certainly anything that oxidizes is prone to going WHOOF! around flames.
This includes non-dairy creamers, paint spray, insecticide sprays (canned or pumped), and sawdust tossed over a fire.
Corn silos know about this intimately.
I was referring to thermite though.
> if there's a good-sized glob of cheese or water or something on the other side you can really be in for a nasty surprise.
My next band will be named Velveeta Disfigurement. The stuff never unmelts.
I think similar of radiant heaters. The heating elements are clearly very hot, glowing even, but you never reach equilibrium with it: your leg will not get that hot. This is because your leg is cooled by conduction and convection (which is basically conduction again) and possibly a little evaporation.
Yeah, radiative cooling/heating is actually super slow compared to any other type. This is why it's so hard to cool anything in space, it's your only option and it kind of sucks at its job.
Wouldn't the other option be ejecting heat "ballast"?
I'm sure that would lead to other issues (sure, ejecting it would move you, but you could just always eject it in the opposite of the direction you want to go, which is how spaceships work in the first place), but what if you had super-cooled ice in a thermos-like enclosure, and as you needed to cool you pulled some out, let it melt, then vaporized it, then superheated the steam, then vented that out the back?
I think you could do that, but mass in space is kind of hard to come by. If it wasn't (like if you're on the moon) you could just use the mass for conduction anyway. If you have to ship it up and consume it like that, that's expensive and limiting.
I'm not sure you can practically superheat the ballast without just causing more heat that you have to deal with. Maybe a heat pump works? Something about that feels vaguely wrong.
If you're about to generate super high temperatures (via a heat pump), might as well use a radiator again. Radiative heat transfer rate scales with temperature to the fourth power. Any such system requires energy, however.
The other thing that helps you is that you're made mostly of water, which is one of the substances with the highest heat capacity. So it's hard to heat up or cool.
Great examples!
That's actually most of space. Space is a very hot environment, especially where we are so close to the sun. Think about it. When you stand outside in the sun you heat up. All that heat is coming from the sun. But a lot of it was filtered by the atmosphere, so if you're in space near earth it will be hotter than standing at the equator on a sunny day, in terms of radiation.
Then there's the fact that heat is very difficult to get rid of when in space. The ISS's radiators are much bigger than its solar panels. If you wanted to have a very-long eva spacesuit you'd have to have radiators much bigger than your body hanging off of it. Short evas are handled by starting the eva with cold liquids in the suit and letting them heat up.
All of the mockups of starships going to Mars mostly fail to represent where they're going to put the radiators to get rid of all the excess heat.
> If you wanted to have a very-long eva spacesuit you'd have to have radiators much bigger than your body hanging off of it.
I was curious about this! The Extravehicular Mobility Units on the ISS have 8 hours of life support running on 1.42 kg of LiOH. That releases ~2 kJ per gram used, so .092 watts.
The 390 Wh battery puts out an average of 50 watts.
And the human is putting out at minimum 100 watts with bursts of 200+.
Long term it's probably reasonable to need at least 200 watts of heat rejection. That's about a square meter of most radiator, but it needs to be facing away from the station. You could put zones on the front/back and swap them depending on direction, as long as you aren't inside an enclosed but evacuated area, like between the Hubble and the Shuttle. The human body has a surface area of roughly 2 m^2 so its definitely not enough to handle it- half of that area is on your arms or between your legs and will just be radiating onto itself.
It's also not very feasible to have a sail-sized radiator floating around you. You'd definitely need a more effective radiator- something that absorbs all your heat and glows red hot to dump all that energy.
Or, evaporative cooling for spacewalks. Water heat of evaporation at 25°C is 678 Wh/kg, so 200W of heat is about 0.3 kg per hour. Quite manageable!
EDIT: Apparently the Apollo suits did this. An interesting detail is that they used sublimation (evaporating ice directly to vapor), because I suppose that's a lot more practical to exchange the heat.
Reminds me of the book Saturn Run, by John Sanford - which has a lot of effort put into the technology and radiation of heat in their space ship. Fun science fiction book.
I recall a good treatment of this issue in the early part of Joe Haldeman's classic The Forever War. Highly recommended.
Started reading a preview of that. It starts really well. Thanks.
See also: "let's build data centres in space, it's cold up there!"
Per wiki: radiators reject 100-350 watts per m^2 and weigh ~12 kg per m^2. Not unlikely you would need 10x as much radiator as server. You need about as much area for radiators as you do for solar panels, but radiators are much heavier.
That also makes nuclear totally infeasible- since turbines are inefficient you'd need 2.5x as many radiators to reject waste heat. Solar would be much lighter.
https://en.wikipedia.org/wiki/Spacecraft_thermal_control#Rad...
Nuclear power is very feasible in space. Perhaps you're overlooking that radiated power scales with the quartic of absolute temperature (T⁴); it's not difficult at all to radiate heat from a hot object, as it is for a room-temperature one.
(How hot? I won't quote a number, but space nuclear reactors are generally engineered around molten metals).
Yeah, fair to say its feasible. ROSA on the ISS produces 240 W/m^2 and weighs 4 kg/m^2.
The S6W reactor in the seawolf submarines run at ~300 C and produce 177 MW waste heat for 43 MWe. If the radiators are 12 kg/m^2 and reject 16x as much heat (call it 3600 W/m^2) then you can produce 875 watts of electricity per m^2 and 290 watts at the same weight as the solar panels. Water coolant at 300 C also needs to be pressurized to 2000+ PSI, which would require a much heavier radiator, and the weight of the reactor, shielding, turbines and coolant makes it very hard to believe it could ever be better than solar panels, but it isn't infeasible.
Plus, liquid metal reactors can run at ~600 C and reject 5x as much heat per unit area. They have their own problems: it would be extremely difficult to re-liquify a lead-bismuth mix if the reactor is ever shut off. I'm also not particularly convinced that radiators running at higher temperatures wouldn't be far heavier, but for a sufficiently large station it would be an obvious choice.
It goes up to 1,344 °C with Li, I think—it's a very different engineering space from the stuff on Earth.
The Soviet ones used K (or maybe NaK eutectic); there's a ring of potassium metal dust around the Earth people track by radar (highly reflective)—a remnant from one of them exploding.
The idea is not completely without merit. In gravity less environment, you can have much bigger and much thinner structure possible than on Earth.
Also the radiated heat from the Sun won't have much effect if the heat sink panels are facing perpendicular to the sun with two sides pointing sideway to deep space to radiate away the heat.
But boiling water is just a few hundred Kelvin, this is tens of thousands. Would EVA spacesuits be able to radiate that much away if it was really that hot but for the atmosphere absorbing some?
I know it is much hotter, but that's way way hotter and they only find it at a "wall" way farther out.
This is more the temperature of the solar wind, dwarfing the steady state temperature you'd reach from the photonic solar radiation at any distance. The Sun's blackbody varies from like 5000K to 7000K, you won't see objects heated in the solar system heated higher than that even with full reflectors covering the field of view of the rear with more sun and being near the surface of the sun, other than a tiny amount higher from stellar wind, tidal friction, or nuclear radiation from the object's own material I don't think.
> Would EVA spacesuits be able to radiate that much away if it was really that hot but for the atmosphere absorbing some?
Yes! The tiny number of particles are moving really fast, but there are very few of them. We are talking about vacuum that is less than 10^-17 torr. A thermos is about 10^-4 torr. The LHC only gets down to 10^-10 torr. At those pressures you can lower the temperature of a kilometer cube by 10 thousand kelvin by raising the temperature of a cubic centimeter of water by 1 kelvin. There is very little thermal mass in such a vacuum which is why temperature can swing to such wild levels.
This is also why spacecraft have to reject heat purely using radiation. Typically you heat up a panel with a lot of surface area using a heat pump and dump the energy into space as infrared. Some cooling paints on roofing do this at night which is kind of neat.
To add to this: Most of the heat the EVA suits deal with is generated by the human inside not the giant ball of nuclear fusion 8 light minutes away.
Solar radiation is roughly 1 kilowatt per square meter. Human beings generate about 0.1 kilowatts. A good suit will try to reject as much of that kilowatt as possible. Also your dark side will radiate heat but the temperature differential is much lower.
Suits are insulating for a reason. You want to prevent heating on the sun side and prevent too much cooling on the space side. Your body is essentially encapsulated in a giant thermos.
Cooling is achieved using a recirculating cold water system that is good for a few hours of body heat. Water is initially cooled by the primary life support system of the spacecraft before an EVA. Pretty much it starts off pretty cold and slowly over time comes up to your body heat. Recent designs use evaporative cooling to re-cool the water.
Life support systems are so cool.
Absorbed light too but that's a bit easier to deal with and is why most things are white or reflective on the outside of anything in space that's not intentionally trying to absorb heat.
At this low density, temperature is very different from what you are used to experiencing. You have to work through a heat flux balance to really get a grasp of it.
Temperature is just the heat of particles moving. In the extreme case of a handful of N2 molecules moving at 1% the speed of light, it has a temperature of something like 9 billion Kelvin. But it's not going to heat you up if it hits you.
Even at low density, if it were a large volume, solid objects would heat up to that ambient temp. But this one is a minor volume and you would still be radiating it away much faster and not reach anywhere near the ambient temperature. In the middle of a large volume thoigh, you'd get too much incoming thermal radiation from particles within the volume and not be able to shed heat anywhere through radiation.
Lack of radiators is endemic in sci-fi. All those cool starships and torch rockets would bake their crews and then melt.
I didn't like the Avatar films except for the starships, which are among the more physically realistic in construction including massive radiators. They'd probably need to be even bigger though IRL if you're talking about something loony like an antimatter rocket.
> Think about it. When you stand outside in the sun you heat up. All that heat is coming from the sun. But a lot of it was filtered by the atmosphere, so if you're in space near earth it will be hotter than standing at the equator on a sunny day, in terms of radiation.
I think you’re missing the key point - heat transfer. The reason we feel hot at the beach is not solely because of heat we absorb directly from solar energy. Some of the heat we feel is the lack of cooling because the surrounding air is warm, and our bodies cannot reject heat into it as easily as we can into air that is cool. And some is from heat reflecting up from the sand.
Theres a heat wave across much of the US right now. Even when the sun goes down it will still be hot. People will still be sweating , doing nothing, sitting on their porches. Because the air and the surrounding environment has absorbed the sun’s heat all day and is storing it.
That’s what you’re neglecting in your analysis of space.
Okay this may sound silly but what about a solar powered ac for cooling? Like solar radiation is 6000K right, so if you used that to pump your waste heat into say a 1000K radiator (aimed away from the sun obviously) I'm thinking it might give you plenty of negentropy but also radiate away heat at a decent pace.
Skip the Sun! There's an "atmospheric window" in the IR. If you make a material that emits/absorbs (they're reversible) only in that region, and don't expose it to the Sun, then it will cool down to the temperature of space, roughly 3K or -270°C. In practice, it won't cool down anywhere near that much. It'll steal energy from it's surroundings due to conduction/convection, and the amount of energy that's actually radiated in this band by a slightly below room temperature material is pretty minimal. Still neat, entirely passive cooling by radiating to space!
https://en.wikipedia.org/wiki/Atmospheric_window
https://en.wikipedia.org/wiki/Passive_daytime_radiative_cool...
Note that for most of the United States, you must resurface your roof twice a year for this to be effective.
It's a thing in from thousands of years ago https://en.m.wikipedia.org/wiki/Yakhch%C4%81l and today https://en.m.wikipedia.org/wiki/Passive_daytime_radiative_co...
for PDRC there are a couple good videos about it from NightHawkInLight https://youtu.be/N3bJnKmeNJY?t=19s, https://youtu.be/KDRnEm-B3AI and Tech Ingredients https://www.youtube.com/watch?v=5zW9_ztTiw8 https://www.youtube.com/watch?v=dNs_kNilSjk
Acs don't get rid of heat, they just move it around. At some point you need to put the heat somewhere and then your just back to giant radiators
Radiative heat transfer is proportional to T^4. If your suit is 300 K(80F), bumping the temperature up by 100 C lets you radiate 3.16x as much heat from the same area.
https://en.wikipedia.org/wiki/Absorption_refrigerator
> An absorption refrigerator is a refrigerator that uses a heat source to provide the energy needed to drive the cooling process. Solar energy, burning a fossil fuel, waste heat from factories, and district heating systems are examples of heat sources that can be used. An absorption refrigerator uses two coolants: the first coolant performs evaporative cooling and then is absorbed into the second coolant; heat is needed to reset the two coolants to their initial states.
https://www.scientificamerican.com/article/solar-refrigerati...
> Fishermen in the village of Maruata, which is located on the Mexican Pacific coast 18 degrees north of the equator, have no electricity. But for the past 16 years they have been able to store their fish on ice: Seven ice makers, powered by nothing but the scorching sun, churn out a half ton of ice every day.
Yes? That's in the atmosphere where heat rejection is a vastly easier problem than in vacuum, thanks to convection.
It literally doesn't matter what your refrigeration process is. You have to "reject" the heat energy at some point. In space, you can only do that with large radiators.
There is no physical process that turns energy into cold. All "cooling" processes are just a way of extracting heat from a closed space and rejecting it to a different space. You cannot destroy heat, only move it. That's fundamental to the universe. You cannot destroy energy, only transform it.
Neither link is a rebuttal of that. An absorption refrigerator still has to reject the pumped heat somewhere else. Those people making ice with solar energy are still rejecting at minimum the ~334kj/kg to the environment.
An absorption refrigerator does not absorb heat, it's called that because you are taking advantage of some energy configurations that occur when one fluid absorbs another. The action of pumping heat is the same.
The question was 'what about a solar powered ac for cooling?', yes?
Giant radiators don't make ice.
The proposed method of pumping heat into someplace hot to make it hotter doesn't work. But there area definitely ways to do solar powered ac for cooling.
The Second Law of Thermodynamics would like a word with you.
I provided links. It's how propane-powered fridges work. And it was a homework problem in thermodynamics class.
Since this discussion is still active, I think hwillis was the only one that got my idea. Pumping heat into the radiators will make them hotter then they would be by just passive conduction, and then the T^4 radiation scaling means that the radiators will start radiating a lot, i.e. a lot of heat will be sent into deep space.
The plasma inside arc lamps (e.g. xenon headlights) are somewhere around 6,000-10,000 K.
Then there are things like fusion reactors where the temperature is in the millions of degrees and the whole point of the design is to keep the heat in.
Edit: although interestingly in an electric arc, often the electrons have a higher kinetic energy (temperature) than the heavier ions and atoms in the plasma. It's a highly non-equilibrium situation. That plays into your "high temperature, slow transfer" thing quite nicely: even the atoms within the plasma don't reach the full temperature of the electrons.
Came to say this about fluorescents, but even the tungsten filament in an old style bulb could easily be 5000K which is ~8500F.
What is the temperature on either side of this “wall”? My mental model here, which is probably incorrect, is that the “temperature” on the outside of the wall could be higher but the density is much lower, thus even less heat transfer going on (but, still, high energy particles that can hit you, registering a high temperature). I get all kinds of mixed up regarding the difference between heat transfer and measured temperature.
It's one of the reasons I love Oxygen Not Included so much. That game's materials have both Thermal Conductivity and Specific Heat as stats, and density plays into it as well.
Temperature is a totally valid measurement. For physicists. Not really for clickbait articles. High energy particles wouldn't attract as many views.
If it were really that hot we'd never observe the CMB at a balmy 2.7K.
I thought the same thing too. It is very hot, without having very much heat - in a way.
The Parker Solar probe encounters a similar situation where it has to handle high amounts of direct radiation, but the latent/ambient environment is full of incredibly hot particles at very low density (because they are so hot) which means it isn't that hard to make the probe survive it.
See also: the exosphere. Helium and Hydrogen in Earth's atmosphere float up above the others and form a layer which hangs out around 1000 °C. Despite the high temperature, you'd probably get hypothermia if you stayed too long in the shade at that altitude (supposing the low pressure didn't get you first).
Temperature, it would seem, is an idea that would only have developed at the bottom of a gravity well.
Just like the rest of space - very very cold, but very empty.
>It’s very odd to think of something extremely hot but with almost no density
Not at all odd, in fact very normal, consider any Hollywood actress who gets by on looks alone, your Pamela Andersons or Megan Foxes of the world.
Perhaps change the link to the original NASA JPL post: https://www.jpl.nasa.gov/news/voyager-2-illuminates-boundary...
Seems I no longer can edit it but that link doesn't directly reference the high temperature environment, unless I misread it?
I often think about how cold our lifeforms on earth are, relative to temperatures of things in the universe. 0 Kelvin is theoretical lowest possible temp, quasars are apparently > 10 trillion Kelvin (10,000,000,000,000K), yet all life we know of is between what, 250K and 400K?
Basically it's because the relevant structures are somewhat fragile. Matt Strassler has a good post about "why does everything we care about move so slowly compared to the cosmic speed limit?" (https://profmattstrassler.com/2024/10/03/why-is-the-speed-of...), and the answer is, it's because we're made of atoms, atoms are held together by the electromagenetic force, and that's only so strong, if things moved way faster then collisions would tear atoms apart. But of course life is dependent not only on atoms, but also on electromagnetic bonds much weaker than the ones that hold atoms together. So this limits how hot it can get.
If you’ll excuse a bit of trivia: SI units named after people are not capitalized. So we have newton, joule, weber, kelvin, named after Newton, Joule, Weber, and Kelvin. (But their abbreviations are capitalized: N, J, Wb, K.)
Correct. The parent of your post should have written "10 trillion kelvins", "10 terakelvins", or "10 TK". The article wrote "Temperatures there reach an astonishing 30,000-50,000 kelvin" instead of "kelvins" (or better yet, 30–50 kK).
Very few people use the unit kelvin correctly. ( https://www.reddit.com/r/Metric/comments/126sniq/everyone_mi... )
The only exception regarding capitalization is that the person Celsius is capitalized in the multi-word unit "degree(s) Celsius", and the pluralization is on "degree".
Good point about pluralization. I tend to be confused about that because we don't pluralize units in Norwegian (except the equivalent of degrees). But confusingly, in English, you sometimes see people trying to pluralize the abbreviations, such as kgs for kilograms. Or (even worse) ms for meters. That way madness lies.
"You aren't really famous in math or science until people stop capitalizing your name"
Joke I heard in the math department.
0 Kelvin is theoretical lowest possible temp
Let me introduce you to negative temperature systems!
https://en.wikipedia.org/wiki/Negative_temperature
Negative temperatures are hotter than positive temperatures, though, so this isn't really relevant to the parent comment.
I was aware of this, but you putting it into numerical terms rather than an intuitive understanding is really cool. Even a small fire is dramatically hotter than life, yet nothing in comparison to what happens outside of our relatively frozen little bubble here on Earth
We're also interestingly enough at around the geometric mean between atoms and stars! (as in the scale of humans)
Well, lifeforms on earth are all pretty dependent on being water based, and water in the liquid state specifically. Maybe there is a possibility of exotic life based on some other types of chemistry and/or phases of matter. But the fact that earth happened to form in this particular goldilocks zone for water-based life is probably why that's the only life we can see for now.
I have to mention Robert L. Forward’s Dragon Egg—it explores life on a white dwarf with nuclear reactions instead of chemical ones. Not the best book, IMHO, but a fun thought to entertain.
Well unless there's some ghost-like life form in a gas state, we sort of need the molecules to stay together to form life.
Thought this was an interesting example of reading the headline vs reading the article.
Headline: > NASA's Voyager found a 30k-50k Kelvin "Wall"... Article: > While not a hard edge, or a "wall" as it has sometimes been called...
I remember being in school in 2006 and being told that outside of our solar system is a "wall of fire" that we would never be able to cross.
I don't know if any of this info was speculated at that point in time, but it turns out that teacher was at least partially correct!
Probably true, in that if you try to travel interstellar distances you'll going to have to deal with very hot particles hitting your ship on occasion. If you travel slowly the more time you're going to be spend getting hit by high energy particles. If you try to travel quickly you're going to have to deal with more relatively high energy particles. It's potentially enough to make interstellar travel impossible.
Systems we built in the 1970s were able to easily pass through this though. Which doesn't seem to indicate that it would make interstellar travel impossible.
Systems from the 1970s travel at, by interstellar standards, agonizingly slow speeds. The voyagers will be exposed to hard radiation for thousands of years before they get anywhere interesting. They will not survive.
Not sure exactly why you're responding to me. The comment I was responding to was talking about the hot particles that would be encountered, and that their existence could preclude future interstellar missions.
What level of "hard radiation" are they now getting bombarded by that we will be unable to shield systems from in far future interstellar space travel?
I'm saying the Voyager probes don't make a counter example to interstellar travel being impossible. That's still very much an open question. We might be able to develop adequate shielding to protect spacecraft from radiation over mildly geologic timespans, but we might not. I'm certain it won't be as easy as you seem to think it is.
(Unless you count slinging a dead pile of former computers through a distant star system as successful interstellar travel, but that's not what most people are interested in.)
Imagine if a dead pile of computers that wasn’t ours arrived in our solar system, I’d call that successful by some metric
It's impossible for many reasons unless there are physics we haven't discovered yet. To me that's the simple answer for the Fermi paradox.
The Fermi paradox doesn't require travel, though. The lack of any sign of life at all is still surprising (no radio signals, etc), even if we knew it couldn't physically come here.
It would take a lot of power to send even a radio signal that could be picked out from the noise at a few light years. Add a requirement for that signal to be more or less continuous over geologic timescales - we’ve only been able to emit and detect these for ~100 years - and my personal surprise diminishes rapidly. Huge distances in time and space with human-level technology make detection highly unlikely.
Yes, and I would add my favorite hypothesis to the paradox, an anthropocentric assumption theory of self importance... or let's call it an anthropocentric bias:
Humans tend to define intelligence, life, and communication based on our own structure -carbon-based biology, electromagnetic signaling, language, symbolic thought, etc. This narrows the scope of our search.
We assume other civilizations want to communicate, would use similar media (radio, light, mathematics), and would send signals we could interpret. This ignores other potential modalities (quantum, neutrino, gravitational, exotic matter, etc.) or entirely non-signal-based forms of interaction.
We may not even recognize signs of intelligent activity if they don't resemble our expectations, ie entire civilizations could exist in forms of computation or energy we can’t perceive.
We assume ET intelligences are aligned with our timeframe or curiosity. Maybe they don’t care to communicate, see us as trivial, or operate on million-year attention spans.
It may reflect less the silence of the cosmos and more the limits of our understanding, especially the assumption that we're capable of detecting or interpreting intelligence beyond Earth. A epistemic humility, or rather our lack of it.
Nobody would be communicating with neutrinos or gravitational energy. EM radiation is way easier to emit and detect, and at cosmic distances they all scale exactly identically (inverse square law). The other things you mentioned are mostly sci-fi inventions and there’s nothing in known or unknown physics that would hint towards them being plausible communication media.
It’s not about being shortsighted, it’s about everyone being constrained by the same laws of physics. Our models, however imperfect, are still unreasonably good.
The counter argument is that even if civilizations exist with all the properties you described, given the vastness of space, there should be another civilization that pattern matches to us.
Sure! All the hypothesis in the Fermi paradox deal ultimately with calibrating our expectations of making contact, not with denying the existence of "STEM-enabled" species like us yearning for an alien encounter.
There's epistemic humility, then there's indulging in unfalsifiable fantasies in the name of not ruling anything out.
> Humans tend to define intelligence, life, and communication based on our own structure -carbon-based biology, electromagnetic signaling, language, symbolic thought, etc.
I would posit that none of these properties are coincidences, and are in fact likely to evolve convergently in most if not all circumstances hospitable to life. In particular I very much expect ET life to be carbon based; I don't believe there's a true viable alternative outside scifi (hint: silicon ain't it).
> entire civilizations could exist in forms of computation or energy we can’t perceive.
Could they? Really? There aren't that many gaps in the Standard Model. The aliens could be made of dark matter, I guess, and remain forever undetectable, but that's not to far off believing in invisible fairy kingdoms. And it still wouldn't explain why the baryonic sector is so devoid of detectable life. Ethereal undetectable aliens don't mean regular ones can't also exist.
> Maybe they don’t care to communicate, see us as trivial, or operate on million-year attention spans.
This one I'll grant (sort of: what's the evolutionary path toward such entities arising?), but it's still weird that we haven't seen any sign at all of them. These entities live on million-year timescales but have no visible effect on their surroundings? Why?
And more importantly, why is that the only thing that happens? Because if it isn't the only thing, then the question remains of why can't we see anything else?
Radio signals aren't the only sign. I'd really love to see some sign of megastructure engineering, but even detecting O2 in an extraterrestrial atmosphere would be huge.
Those would likely be extremely low albedo objects, so harder to detect than radio signals by many orders of magnitude.
A Dyson sphere would be virtually invisible, except for a hard to reconcile "blackbody-profile versus apparent size" ratio.
It's not a new idea. The posted article is just about Voyager apparently observing the phenomena more closely. Voyager 1 had already reached the termination shock of the heliosphere in 2004 and Voyager 2 in 2007. The heliosphere containing a heliosheath, past the boundary of the termination shock, composed of compressed superhot solar winds had been hypothesized, due to the compression of the solar winds that begins at the termination shock.
Reading the article, the wall is referring to the heliopause, which is the boundary past the heliosheath. Also, it looks like both voyagers traveled past this over a decade ago.
Also sort of the plot of Solar Winds (1993, Epic MegaGames). https://en.wikipedia.org/wiki/Solar_Winds
That’s weird. What class was it and what was their motivation for telling you this?
It's great that we're still getting data from these two probes 50 years later but it absolutely sucks that these are the only 2 probes we have out there. How long can they keep running, another 5 or 10 years max? It's already considered an engineering miracle that they are still going.
What of people growing up 10, 20, 30 years from now? They'll be taught in school about stuff from Voyager and then told 'and that was what we learned in the golden age of space exploration, which ended long before you were born because we couldn't be bothered to keep at it.' Having grown up in the 70s, I feel somewhat betrayed that we just just gave up on doing moon stuff, rendering a whole generation's aspirations on space exploration into a lie. The claims that 'there is nothing more to discover up/out there' is nonsense, much like the claims that 'chips can't be made any smaller' that I would hear back in the 32nm period.
The lack of long-term commitment to exploratory space is a terrible waste. To be sure we have been doing some stuff in system, but if he had kept putting out deep space probes every few years with more advanced instruments we would have learned a lot of other things by now, and we would have a long-term stream of new data coming in for the future. Now arguments for launching more deep space probes are dismissed with 'it'll take decades before we get anything useful back.' Yeah, because we stopped iterating! Meantime allowing that sort of exploration to become anachronistic is one reason we are overrun with flat-earthers and other science woo even at the highest levels of government.
> How long can they keep running, another 5 or 10 years max?
NASA hopes to make it the 2030s with 1 remaining science instrument on each[0]. Currently, Voyager 1 has 3 remaining instruments (of 11) and Voyager 2 only has 2. ~2036 is the maximum cutoff, as then they will be out of range of the Deep Space Network[1].
[0] https://www.jpl.nasa.gov/news/nasa-turns-off-two-voyager-sci...
[1] https://science.nasa.gov/mission/voyager/frequently-asked-qu...
New Horizons is being sent into the interstellar medium.
More and more deep space missions are orbiters or landers now, so there are fewer flyby missions that can double as interstellar medium missions like Voyager/Pioneer, but New Horizons is one of them.
Voyager of course took advantage of an alignment of the planets in order to perform the Grand Tour. Apparently it's 175 years before it happens again, FWIW.
I suppose an extra-solar-system probe though would simply need some gravitational slingshotting and not necessarily visit many of the outer planets. I suppose that changes the time scale.
Solar sails for the near term:
https://youtu.be/NQFqDKRAROI?si=AzuL-NZ6JYJ71Rpj&t=883
...which might get up to 22 AU per year. And then in the future: laser-pushed light sails:
https://ia800108.us.archive.org/view_archive.php?archive=/24...
Exploration, especially space exploration, has only ever come with military advantages. If one could interest military agencies that the exploration was in their best interests we could see a space-revival of sorts. That would only last for as long as the military advantage lasts.
This is an unfortunate reality of our society. We've only ever spent dollars in space when it was advantageous to our Department of Defense, and the military in general.
People and companies who have succeeded in space have tied their goals to overarching military objectives. It's the best way to win the space race. Make the military understand they need to do the thing you want to do.
I would say "nationalist ego" instead of military advantages. Edmund didn't bring back any new weapons from the Pole. And, for that matter, our 1960s-70s race was as much (or more) about oneupmanship than gaining real tactical advantage - although of course a lot of the experience gained supported ICBM development.
What sensor is Voyager using to measure "temperature" here?
https://science.nasa.gov/mission/voyager/spacecraft/
It seems they use several tools - inferring from the descriptions, they can measure and compare the data when it gets back here to determine simple things like temps.
Is it possible that one of the sensors failed, thus giving the impression of a sudden change in value?
TFA states that Voyager 1 and Voyager 2 found the same thing and that the data aligns in space too.
Thank you
They're using Plasma Wave Sensor instrumentation:
> https://space.physics.uiowa.edu/plasma-wave/voyager/
50 years in deep space and still delivering useful specific data! Whenever I think of the Voyagers, I cannot help being amazed by the engineering efforts of the Voyager team. A true marvel of engineering that will stay unchallenged for a very long time. Most respect to the team!
Not to mention that the systems are still active and responsive, still maintained while being written in FORTRAN.
Just to be clear, the computers onboard the spacecraft are programmed in assembly language--3 types of computers on each spacecraft, so 3 assembly languages.
The original ground system was mostly written in Fortran. Mission control (i.e., the thing you see on TV!) ran on IBM 360 mainframes. Offline analysis/design/development activities (e.g., developing observation sequences for planetary encounters) ran on Univac 1108 mainframes. Circa 1990, after Voyager 2's flyby of Neptune, the project began moving off the mainframes onto Unix workstations and the original Fortran software was largely replaced by new software written in C and other languages.
ASML is doing crazy stuff also
The chip-factory company? Sure, but what has that to do with senior-citizen-aged electronics leaving the Oort cloud?
Fascinating that we're still getting useful science out of almost 50 year old tech. I think New Horizons is the only other probe that's expected to go interstellar.
Are the particle velocities that are being measure correlated at all? As in, flowing away from the sun or similar? I'd think that something with a well-defined "temperature" would be composed of randomly moving particles with a mean velocity of zero. I'd also be interested in the distribution of particle speeds. Would anyone one consider a collimated beam of neutrons to have a temperature?
And I wonder what the distance mean free path length is. I suppose that must be pretty large. So that the T^4 Boltzmann radiation law doesn't really apply to these ~40,000 Kelvin temperatures? Or maybe the emissivity of hard vacuum is really low? I guess I've never thought about it before.
"While not a hard edge, or a "wall" as it has sometimes been called, here both spacecraft measured temperatures of 30,000-50,000 kelvin (54,000-90,000 degrees Fahrenheit), which is why it is sometimes also referred to as a "wall of fire". The craft survived the wall as, though the particles they measured were extremely energetic, the chances of collision in this particle-sparse region of space are so low that not enough heat could be transferred to the duo."
Also, worth noting that these temperatures are not that high as far as plasmas go. This is 3-5 eV, which is firmly in the "low temperature" regime (like a fluorescent bulb).
Is there a chance this is an instrument error? Seems a strange phenomenon.
This isn't strange at all, but rather an artifact of the nature of heat energy in a medium. Heat is the uncorrelated movement of particles that evens out to zero effective velocity. Temperature is the measure of the velocity magnitude of these individual particles. This is independent of the medium's density.
That's the best part of them sending two of them. It can't be a random error.
I'm just a layperson, but I'd suspect the research is sound.
I hate the telephone tag, livescience.com-type journalism. Instead, I'd love to read an abstract and methods. The research must talk about this in detail and explain how the conclusions are reached. It probably isn't too inaccessible.
I suspect that there may be many such measurements correlated between both probes taken against some other baseline signal or an observed return to the mean.
30K to 50K K? K. It’s not clear what the range represents. Were they polling and those are max and min values they got? Was that their range of uncertainty because it’s hard to accurately measure there?
Also, I hate the ambiguity of a title that references “Voyager Spacecraft” so it’s unclear if it was one or both.
First paragraph of the article:
"In 1977, NASA launched the Voyager probes to study the Solar System's edge, and the interstellar medium between the stars. One by one, they both hit the "wall of fire" at the boundaries of our home system, measuring temperatures of 30,000-50,000 kelvin (54,000-90,000 degrees Fahrenheit) on their passage through it."
That paragraph is the problem. It doesn't actually explain it. Were they continuously polling temps and reached as low as 30K and as high as 50K? If the 'wall of fire' is based on temps, did they have a continuous rise? what was the temp just outside the 'wall'?
Small k for kilo-, big K for kelvin.
I skimmed the links that TFA provided and couldn't find the source of that figure. With rare space plasmas near shocks it's typical to have non-thermal distributions where the temperature isn't well defined. I don't think it's anything to get to excited about without having a proper article from NASA instead of IFL slop.
So it's more the temperature range uncertainty? is that a product of the environment (and with few particles one can actually measure) or a product of the measurement apparatus?
What happens when an object enters a solar orbit inside this wall? Theoretically, it could be heated to life-sustaining temperatures?
Well, that's what happens on Earth, so technically 'yes'.
But if you mean "as soon as it enters", no.
This is obviously the thing aliens have setup to obscure themselves from us. Obviously.
Oh great yet another website that has the obligatory cookie banner but won't give me a reject all option
Can someone explain to me why this isn't melting Voyager?
> why this isn't melting Voyager?
Same reason why you can sit in a sauna with very hot air or pass your hand through a flame quickly without severe burns. Low density matter does not transfer heat very well. And space is especially devoid of matter.
There is no thermal mass. It's almost pure vacuum but the handful of particles that are out there are whizzing around at high energies that make them very hot.
Interesting to think that while it's not a concern to Voyager at its pokey 17km/second, a true interstellar ship traveling at some respectable fraction of C would compress the diffuse interstellar gasses enough to make them a potential hazard. You frequently see people saying stuff like "if we could accelerate to a high fraction of C you could get anywhere in the galaxy in a single lifetime", but it may not be so simple.
> but [a true interstellar ship traveling at some respectable fraction of C] may not be so simple.
And that is the champion understatement of this thread!
I suppose an interstellar ship that could accelerate to a notable fraction of c would also be powerful enough to leave the ecliptic and avoid this heat cloud.
Most replies are talking about the low density of the matter in that area, which is one part of the equation. The other part of the equation is radiative heat transfer. Without radiation pulling heat away, the spacecraft would asymptotically heat up to the temperature of the surrounding matter.
Radiative heat transfer, roughly speaking, tries to bring the temperature of the probe to the average temperature of all the matter that it has line of sight to -- somewhere between the temperature of the sun and the temperature of the cosmic background radiation. Since the probes are far away from the sun, this average temperature is very low.
Both effects are present everywhere. On Earth, with our dense atmosphere, conductive transfer is usually the stronger effect. In space, with extremely low density, radiative heat transfer is stronger.
High temperature, almost no actual heat because there are very few particles.
The average stuff is very hot, but there's also basically no stuff out there anyway, so you won't run into enough of it to care.
Imagine that there is one venomous and aggressive snake (in a cute little survival-suit) in some random spot in Antarctica. This means "the average snake in Antarctica" is ultra-dangerous.
But there's only one, and it's almost impossible for you ever to meet, so in practical terms it's still safer than Australia. :p
Because very few hot particles ever touched the craft. The gas is so incredibly thin that Voyager largely sailed straight through the space in between molecules.
The craft survived the wall as, though the particles they measured were extremely energetic, the chances of collision in this particle-sparse region of space are so low that not enough heat could be transferred to the duo.
Temperature is a measure of the kinetic energy of a particle, so they can be both extremely hot and extremely diffuse.
This is explained in the article.
It did, but I still didn't understand it. Sorry, not a physics major. And I understand that heat radiates through empty space. Sounds like it's not actually that hot where voyager is, but instead filled with random particles that are that hot.
You're mixing together temperature and heat transfer. That region is very hot, but it transfers very little heat. It's like getting hit with a blast of hot air when you open the oven. The air is hot enough to harm you, but it can't carry enough heat to actually harm you unless you stay there for a long time.
Except where Voyager is, the "air" is so thin there are like a dozens zeroes on the percentage thinner it is, so the amount of heat it carries is also divided by a similar amount.
Each particle is carrying a huge amount of heat, but it gets hit by very few particles. Earth is the inverse; each particle carries a very moderate amount of heat, but you get hit by a lot of them.
In both Edge and Firefox I'm blocked for using Adblock but from what I can tell I do not have adblock on either browser.
Which side of the wall were you on?
This made me giggle
Firefox has enhanced tracking protection and I got through fine with it set to “strict”. Are you on a vpn?
Ah yes, I turned off a bunch of Kaspersky internet security settings and I'm through. This is my work computer I forget what's running in the background sometimes.
That's funny... I'm using Firefox, definitely have an ad-blocker, and had no problem.
https://en.wikipedia.org/wiki/The_Crystal_Spheres
Made me think of this Brin book. The first ship to try to leave the solar system, crashes into an invisible crystal barrier. It's unbreakable.
While in the very-much-breakable sphere around Earth category, there's Unsong (https://unsongbook.com) by Scott Alexander.
I'm confused. The plot summary talks about an impenetrable sphere around our solar system, but also says, "The main character takes part in an expedition to a newly discovered habitable solar system with a shattered sphere." How'd the character escape from our own system?
Says it right here:
> From studying the Nataral's artifacts and writings, they learn that the only way to break the crystal spheres is from the inside.
He just had to go to the other solar system to learn how to go to the other solar system.
> It is also discovered that the Nataral chose to go into a kind of suspended animation around a black hole, joining two even earlier species, to wait for the other civilizations of the universe to develop interstellar flight capabilities.
They used their interstellar flight capabilities to go wait for someone in the universe to develop interstellar flight capabilities. Checks out.
If I recall (its been 25+ years and my copy is in storage), they went there to wait for other civilisations to develop. They were truly early life and there was literally nobody else and they determined that they would be waiting for millions of years, if not billions.
I don't know if it was this book, but the 'suspended animation' was basically pushing several large stars and neutron stars close enough together that the flat space between them was inside an encompassing event horizon, and there they waited, living their lives at an extremely slow (compared to the outside universe) pace.
It crashes into the sphere, but must have also broken it: "the only way to break the crystal spheres is from the inside".
Yeah found it online, the ship that crashed on it broke it.
Unbreakable from outside.
Is it that there is not enough mass beyond the 30k-50k Kelvin wall at the edge of the solar system to attract away things with mass that can carry thermal energy; that thermal mass clumps in the well around the edges and only wisps away, or is that a sidewall boundary of a black hole?
Where is Planet X in relation to said wall of energy density?
Said wall is only sampled by the Voyager probes with a few exit trajectories?
Does said thermal wall extend all the way around the solar system, or is it mostly on one side of the sun; is it a directional coronal wake? Is there symmetry in said thermal wall around the trajectory of the sun?
Is this better explained with SQR Superfluid Quantum Relativity?
Are there other phases of matter at those temperatures?
From the article:
> "As the heliosphere plows through interstellar space, a bow shock forms, similar to what forms as a ship plowing through the ocean
So fluidic space wind and fluidic nonlinear bow shock wakes.
Are there additional heat walls beyond (and probably also before) the first, as there are with more laminar boat wakes?
Is there a gravitational wave "bow shock", too?
"The Heliosphere" https://www.nasa.gov/image-article/heliosphere-4/
From "Two galaxies aligned in a way where their gravity acts as a compound lens" https://news.ycombinator.com/item?id=42159195 :
> "The helical model - our solar system is a vortex" https://youtube.com/watch?v=0jHsq36_NTU
Where are planet X and the heat wall (and/or side wall) in this vortical model of the solar system?
Very cool, our solar system has an atmosphere, which seems obvious but isn’t discussed or taught at least when I was in high school.
One of my favorite quotes from one of my Astro professors is "Everything has an atmosphere, it is a matter of how tenuous".
I think the article shows how relevant this still is today.
You may find this article on wikipedia interesting: https://en.wikipedia.org/wiki/Heliosphere?useskin=vector
Basically, the Oort cloud. Except for the high temps, which are the surprise.
From my understanding the wall is not the Oort cloud but instead the solar winds bouncing off the exterior winds more like how the Pacific and Atlantic oceans don’t mix.
Well, not a surprise. They predicted it before measuring it.