If that blows your mind then think about this: As the universe expanded after the Big Bang, it cooled from unimaginably high temperatures. In principle, this suggest that there could have been a very short window much later, tens of millions of years after the Big Bang, when the background temperature of the entire universe was capable of sustaining life everywhere. Some physicists have suggested this might have created a brief, universe-wide “habitable epoch,” though this remains theoretical.
I'm not an expert, so this is probably not a muture understanding, but it's cool to imagine a universe where life was incredibly abundant.
Edit:
I got this idea from a video, and I found it!
Please transfer all criticism of my comment to this video.
Interesting theory, I'd never heard of it before. All of the sudden, "a long time ago, in a galaxy far, far away", actually seems plausible (although this theory looks like it came well after SW in 2014).
More weird to me is that, at some point before the first stars, the entire universe glowed through the entire rainbow, so there is a moment when, were you to travel back in time, the entire universe would glow blindingly green.
It probably would never appear green, due to the black-body radiation distribution. When the peak is at green, it just looks like white to us. Our sun is kinda a "green" star due to this
But it would go from blue to white to red. Similar colour progression that we can find in the distribution of stars
Indeed! Good point! For some reason, I was under the impression that the CMB was monochromatic (corresponding to a red shifted equivalent of the precise energy of W and Z boson annihilation to produce photons). Thanks!!
I'm skeptical of this. Life doesn't just need a certain temperature, it needs to convert lower entropy energy to higher entropy. A uniform environment temperature does not provide any usable energy. You would still need a star or some other energy source.
It also needs something that can form complex molecules. The lightest element we know of that can form these is carbon. That didn't appear in reasonable quantities until the first stars exploded.
Well, "life as we know it". But for all we know energy rather than matter-based beings could have existed more readily back then, and perhaps struggle to exist now under lower density conditions. Thereby making that earlier era more habitable for their type of life, even as our current era is more habitable for our own type.
Are you dissipating heat in a vacuum, though? Pressure shenanigans aside, would someone's body heat slowly, continually build up, or would they freeze?
I can't really find a good number for how cold you can get and not die, so let's say 20 degrees. That gives 16 degrees to lose.
Meat has a specific heat of about 3.5kJ per kilo per degree, so say you weigh 70kg, that's about 4 million joules to lose before you die.
At 650 joules per second, you've got slightly over 10 minutes. Of course, shivering will burn more calories and stuff, and the panic of impending death will likely stretch it a few more.
I didn't include clothes, because then the maths would make me cry.
At that point, you'll have to calculate the heat transport of the human body, and answer questions like "how long can a person live with frozen skin" and other fun questions I'm not equipped to answer.
You constantly radiate heat. The warmer you are, the faster you radiate it away. In space this is the primary way you lose heat.
In your living room you are constantly bombarded by radiated heat from all the objects that surround you, even if they're just at room temperature, which lessens the effect. In space, not so much.
Someone who knows better might chime in, but as far as I know the trope of rapidly freezing out in space is exaggerated. You would definitely freeze eventually, but perhaps not as dramatically fast as portrayed in The Guardians of The Galaxy for example.
Have you ever looked up at a clear summer night sky? Your face will feel cold. Colder than when looking at the ground. That's because there's not as much stuff radiating heat at you up there.
Heat doesn't work quite like that. In order for heat to transfer efficiently, there has to be "stuff" for it to transfer to. Vacuums are famous for lacking "stuff".
Yes. Like all multipliers the heat of the sun requires not only itself the thing that which is acting but also that which is to be acted upon. If you are a handsome wet rock, the distance you are to the sun effects how your heat is multiplied.
This is not completely correct though. It is our atmosphere/albedo/geological and natural processes that help maintain consistently livable temperatures, not just living in the habitable zone. No atmosphere? We'd be like the Moon, where it is too hot in sunlight and too cold in shade despite being similarly far from the sun as Earth.
If you are in space wearing space suite that doesn't radiate heat properly, you could die from the excessive heat. Once dead your body stops producing heat and the existing heat eventually radiate away and your body freeze.
Space is neither hot or cold because these are property of matter. Since space has very little atoms, it technically has no temperature.
Can't ignore bosons; photon wavelength is a measure of temperature too.
Space has a temperature, which is based on the average of incoming radiation through that space; i.e. the thermal equilibrium to emit as much energy as is absorbed by a theoretical perfectly thermally conductive black body at that point in space.
Based off CMB radiation, space on average is a little over 2.7 kelvin. It'll be hotter near stars, but the void dwarfs matter on a cosmic scale
I guess it depends on definition of the word "temperature".
I was referring to the classical definition
In classical thermodynamics and kinetic theory, temperature reflects the average kinetic energy of the particles in a system, providing a quantitative measure of how energy is distributed among microscopic degrees of freedom.
I know its memes, but the astronaut tim peake discussed the space suits on No Such Thing As A Fish where he said that the whole get-up is like 16+ layers thick, and the only heating inside is for your fingertips, so you dont lose fine motor function.
He said you can be sitting working on a panel outside the station, with one hand facing the sun and one hand facing the shade, and the delta-T of your two hands could be something like 500°C.
Maaaaadness!
(It's been a while since I listened to this episode, my memory of numbers could be skewed.)
Yeah, sorry. Its difference in temperature.
I got delta-T in my head and blinkered in on either making a 'triangle' to denote delta or just write it out, instead of just saying temperature difference.
It's analogous to a combined count of how many people have commented on the post, or shared it (or "reblogged", to use the Tumblr term). It might also include likes? I only use Tumblr occasionally so I'm not sure.
I don't know why Tumblr counts things like this. I sort of like it though — it makes it feel like a distinct place. Tumblr hasn't escaped enshittification, but it makes me happy that it still exists as a little pocket of weirdos
83 Comments
Rooskie91@discuss.online · 75 pts · 194d
If that blows your mind then think about this: As the universe expanded after the Big Bang, it cooled from unimaginably high temperatures. In principle, this suggest that there could have been a very short window much later, tens of millions of years after the Big Bang, when the background temperature of the entire universe was capable of sustaining life everywhere. Some physicists have suggested this might have created a brief, universe-wide “habitable epoch,” though this remains theoretical.
I'm not an expert, so this is probably not a muture understanding, but it's cool to imagine a universe where life was incredibly abundant.
Edit: I got this idea from a video, and I found it! Please transfer all criticism of my comment to this video.
marcos@lemmy.world · 57 pts · 194d
There was probably nothing but helium, hydrogen and a tiny bit of lithium at that period.
panda_abyss@lemmy.ca · 35 pts · 194d
Those are some of the best elements though.
marcos@lemmy.world · 21 pts · 194d
They surely are popular...
kozy138@slrpnk.net · 12 pts · 194d
Top 3 probably
Dicska@lemmy.world · 5 pts · 194d
Yeah, season 8 of helium is just chef's kiss.
te_abstract_art@lemmy.world · 3 pts · 193d
I myself am a caesium guy. Hydrogen is okay but overused
engywook@programming.dev · 14 pts · 194d
Interesting theory, I'd never heard of it before. All of the sudden, "a long time ago, in a galaxy far, far away", actually seems plausible (although this theory looks like it came well after SW in 2014).
The actual paper about it: https://lweb.cfa.harvard.edu/~loeb/habitable.pdf
wolframhydroxide@sh.itjust.works · 7 pts · 194d
More weird to me is that, at some point before the first stars, the entire universe glowed through the entire rainbow, so there is a moment when, were you to travel back in time, the entire universe would glow blindingly green.
SkyeStarfall@lemmy.blahaj.zone · 11 pts · 194d
It probably would never appear green, due to the black-body radiation distribution. When the peak is at green, it just looks like white to us. Our sun is kinda a "green" star due to this
But it would go from blue to white to red. Similar colour progression that we can find in the distribution of stars
wolframhydroxide@sh.itjust.works · 3 pts · 194d
Indeed! Good point! For some reason, I was under the impression that the CMB was monochromatic (corresponding to a red shifted equivalent of the precise energy of W and Z boson annihilation to produce photons). Thanks!!
8baanknexer@lemmy.world · 4 pts · 193d
I'm skeptical of this. Life doesn't just need a certain temperature, it needs to convert lower entropy energy to higher entropy. A uniform environment temperature does not provide any usable energy. You would still need a star or some other energy source.
cynar@lemmy.world · 2 pts · 193d
It also needs something that can form complex molecules. The lightest element we know of that can form these is carbon. That didn't appear in reasonable quantities until the first stars exploded.
teft@piefed.social · 1 pts · 194d
OpenStars@piefed.social · 0 pts · 193d
Well, "life as we know it". But for all we know energy rather than matter-based beings could have existed more readily back then, and perhaps struggle to exist now under lower density conditions. Thereby making that earlier era more habitable for their type of life, even as our current era is more habitable for our own type.
Fedizen@lemmy.world · 58 pts · 194d
Goldilocks space is like "my breath immediately turns solid in the shade and my body is turning to charcoal in the direct sunlight"
You need a giant buffer of atmosphere to help average the temperature a bit. Maybe some kind of large rock with a dense atmosphere?
MeatPilot@sh.itjust.works · 30 pts · 194d
That or a giant space turtle with elephants holding a flatten rock on it's back.
dwemthy@lemmy.world · 17 pts · 194d
A strong thaumic field slows down the sunlight too. Doesn't change the heat but it's nice to see sunrise pour across the landscape like honey
SkaveRat@discuss.tchncs.de · 7 pts · 194d
But what's holding up the elephants?
C8r9VwDUTeY3ZufQRYvq@sopuli.xyz · 4 pts · 194d
More elephants, obviously
OpenStars@piefed.social · 7 pts · 193d
WRONG! It is turtles actually. It's elephants alternating with turtles (and then every tenth level is capybaras) all the way down.
untorquer@lemmy.world · 2 pts · 193d
You're forgetting manatees.
OpenStars@piefed.social · 2 pts · 192d
They took a mental health / exercise break before they get back in there...
untorquer@lemmy.world · 2 pts · 192d
Real MVPs
C8r9VwDUTeY3ZufQRYvq@sopuli.xyz · 2 pts · 193d
I stand corrected.
Fedizen@lemmy.world · 5 pts · 194d
If you go that way you gotta have at least 8 colors.
HeyThisIsntTheYMCA@lemmy.world · 3 pts · 194d
that's not quite right. see that turtle has its own sun and moon chasing it around. and they did the math the sun and moon are superluminal bodies
cynar@lemmy.world · 1 pts · 193d
The other option is a "barbeque roll" a favourite of sci-fi starships, from authors who have done some homework.
You're basically trying to balance half way up a waterfall.
Zwiebel@feddit.org · 36 pts · 194d
Vacuum doesn't have a temperature~
starik@lemmy.zip · 36 pts · 194d
But you will if you sit in a vacuum for a while without a radiation source nearby, and it will be quite low.
Mesophar@pawb.social · 15 pts · 194d
Are you dissipating heat in a vacuum, though? Pressure shenanigans aside, would someone's body heat slowly, continually build up, or would they freeze?
Tar_alcaran@sh.itjust.works · 24 pts · 194d
If you could somehow prevent yourself from dying due to lack of pressure, without blocking heat, you would radiate about 650W more than you generate.
That's using the Stefan Boltzmann law, at normal body temp, perfect blackbody and 1.5m2 of skin. (~ 750 Watt) And then assuming 2000kcal a day (~100W)
You'd cool down pretty quickly.
ivanafterall@lemmy.world · 11 pts · 194d
So how long do I have? Also, if you guys could hurry with the answer...?
Tar_alcaran@sh.itjust.works · 12 pts · 194d
I can't really find a good number for how cold you can get and not die, so let's say 20 degrees. That gives 16 degrees to lose.
Meat has a specific heat of about 3.5kJ per kilo per degree, so say you weigh 70kg, that's about 4 million joules to lose before you die.
At 650 joules per second, you've got slightly over 10 minutes. Of course, shivering will burn more calories and stuff, and the panic of impending death will likely stretch it a few more.
I didn't include clothes, because then the maths would make me cry.
Zwiebel@feddit.org · 5 pts · 194d
Your skin isn't at core temp tho, so the loss rate should be lower I think
Tar_alcaran@sh.itjust.works · 9 pts · 194d
At that point, you'll have to calculate the heat transport of the human body, and answer questions like "how long can a person live with frozen skin" and other fun questions I'm not equipped to answer.
bobo@lemmy.ml · 2 pts · 194d
4,000,000/650/60=102.57 minutes
But that's for a resting body, a shivering one would lose only like 200j/s
Also, you forgot one important aspect, if you're getting bathed by the sun and spinning, you're constantly getting heated up.
Fedizen@lemmy.world · 4 pts · 194d
RIP
Mesophar@pawb.social · 1 pts · 194d
Good to know! I didn't realize humans would radiate heat so much, I wrongly assumed it was more convective and relied on atmosphere
ExperiencedWinter@lemmy.world · 24 pts · 194d
https://en.wikipedia.org/wiki/Black-body_radiation
rockerface@lemmy.cafe · 15 pts · 194d
Heat buildup is actually a problem in space, yeah. You need heat sinks on long term space flights.
DaddleDew@lemmy.world · 11 pts · 194d
You constantly radiate heat. The warmer you are, the faster you radiate it away. In space this is the primary way you lose heat.
In your living room you are constantly bombarded by radiated heat from all the objects that surround you, even if they're just at room temperature, which lessens the effect. In space, not so much.
Someone who knows better might chime in, but as far as I know the trope of rapidly freezing out in space is exaggerated. You would definitely freeze eventually, but perhaps not as dramatically fast as portrayed in The Guardians of The Galaxy for example.
craftrabbit@lemmy.zip · 4 pts · 194d
Have you ever looked up at a clear summer night sky? Your face will feel cold. Colder than when looking at the ground. That's because there's not as much stuff radiating heat at you up there.
Triumph@fedia.io · -7 pts · 194d
Heat doesn't work quite like that. In order for heat to transfer efficiently, there has to be "stuff" for it to transfer to. Vacuums are famous for lacking "stuff".
DaddleDew@lemmy.world · 13 pts · 194d
You're talking about conduction. I'm talking about radiation.
Triumph@fedia.io · 4 pts · 194d
Sure, but radiation acts extremely slowly in the scenario of a person in the vacuum of space.
DaddleDew@lemmy.world · 8 pts · 194d
Yes it is. But it is the main way by which things cool down in space.
That's how satellite electronics are cooled down. They have large heat sinks that slowly radiate heat away.
gens@programming.dev · 3 pts · 194d
Infrared
Bonus: Making Infrared Cooling Paint From Grocery Store Items
hemko@lemmy.dbzer0.com · 2 pts · 194d
It would be pretty warm at earth if the planet didn't radiate some of the heat away
Snowclone@lemmy.world · 2 pts · 194d
Yes. Like all multipliers the heat of the sun requires not only itself the thing that which is acting but also that which is to be acted upon. If you are a handsome wet rock, the distance you are to the sun effects how your heat is multiplied.
pipe01@programming.dev · 1 pts · 194d
Is water wet?
Lemmyoutofhere@lemmy.ca · 4 pts · 194d
No, water makes other things wet.
tensorpudding@lemmy.world · 29 pts · 194d
This is not completely correct though. It is our atmosphere/albedo/geological and natural processes that help maintain consistently livable temperatures, not just living in the habitable zone. No atmosphere? We'd be like the Moon, where it is too hot in sunlight and too cold in shade despite being similarly far from the sun as Earth.
sun_is_ra@sh.itjust.works · 12 pts · 194d
Also its not true that space is "very very cold".
If you are in space wearing space suite that doesn't radiate heat properly, you could die from the excessive heat. Once dead your body stops producing heat and the existing heat eventually radiate away and your body freeze.
Space is neither hot or cold because these are property of matter. Since space has very little atoms, it technically has no temperature.
Techlos@lemmy.dbzer0.com · 2 pts · 193d
Can't ignore bosons; photon wavelength is a measure of temperature too.
Space has a temperature, which is based on the average of incoming radiation through that space; i.e. the thermal equilibrium to emit as much energy as is absorbed by a theoretical perfectly thermally conductive black body at that point in space.
Based off CMB radiation, space on average is a little over 2.7 kelvin. It'll be hotter near stars, but the void dwarfs matter on a cosmic scale
sun_is_ra@sh.itjust.works · 1 pts · 193d
TIL.
I guess it depends on definition of the word "temperature".
I was referring to the classical definition
https://en.wikipedia.org/wiki/Temperature
nexguy@lemmy.world · 15 pts · 194d
The dark side of your body in space is freezing cold while the light side gets hot. You really need to rotate to get that even crispy layer.
J92@lemmy.world · 13 pts · 193d
I know its memes, but the astronaut tim peake discussed the space suits on No Such Thing As A Fish where he said that the whole get-up is like 16+ layers thick, and the only heating inside is for your fingertips, so you dont lose fine motor function. He said you can be sitting working on a panel outside the station, with one hand facing the sun and one hand facing the shade, and the delta-T of your two hands could be something like 500°C.
Maaaaadness! (It's been a while since I listened to this episode, my memory of numbers could be skewed.)
LemmyKnowsBest@lemmy.world · 5 pts · 193d
What is a "delta-T?"
HugeNerd@lemmy.ca · 5 pts · 193d
Difference in temperature.
J92@lemmy.world · 4 pts · 193d
Yeah, sorry. Its difference in temperature. I got delta-T in my head and blinkered in on either making a 'triangle' to denote delta or just write it out, instead of just saying temperature difference.
Apologies.
DylanMc6@lemmy.dbzer0.com · 9 pts · 194d
Not anymore, there's a blanket
HugeNerd@lemmy.ca · 8 pts · 193d
Space isn't cold. It isn't hot either.
resipsaloquitur@lemmy.world · 3 pts · 193d
PV=nRT.
untorquer@lemmy.world · 3 pts · 193d
When you treat n as the independent variable...
SLVRDRGN@lemmy.world · 3 pts · 193d
I forget sometimes that while space isvery cold, it's also an incredible insulator.
untorquer@lemmy.world · 3 pts · 193d
In terms of convection sure, but radiation against -270C will freeze you quickly enough.
HugeNerd@lemmy.ca · 4 pts · 192d
And in direct sunlight at Earth distance you'll cook. Space isn't cold. It isn't anything. You are describing your temperature.
untorquer@lemmy.world · 1 pts · 192d
Im describing heat flux in space, which the vast majority of is far from any heat source. Get out of here with your heliocentrism, eeewwww!
genuineparts@infosec.pub · 4 pts · 194d
The Sun is a mass of incandescent gas, A giant nuclear furnace.
LemmyKnowsBest@lemmy.world · 3 pts · 193d
Where hydrogen is built into helium at a temperature of millions of degrees 🎵
Tollana1234567@lemmy.today · 3 pts · 194d
a massive plasma cannon.
pr06lefs@lemmy.ml · 2 pts · 194d
balmy is an understatement
MonkderVierte@lemmy.zip · 2 pts · 192d
Only with protective layers though.
JuliaSuraez@lemmy.world · 2 pts · 192d
It’s funny how something can be technically correct and still feel counterintuitive. Space really is extreme in every direction.
Digit@lemmy.wtf · 1 pts · 193d
what this mean?
AnarchistArtificer@slrpnk.net · 4 pts · 193d
It's analogous to a combined count of how many people have commented on the post, or shared it (or "reblogged", to use the Tumblr term). It might also include likes? I only use Tumblr occasionally so I'm not sure.
I don't know why Tumblr counts things like this. I sort of like it though — it makes it feel like a distinct place. Tumblr hasn't escaped enshittification, but it makes me happy that it still exists as a little pocket of weirdos
Digit@lemmy.wtf · 2 pts · 193d
Thanks.
It seemed implausible that it'd have had that many "community notes".