Weirdest space fact that you know

[lemon cup]

11 hours ago, Ikkjot said:

I don't know if this is either weird or shocking but the fact is: Space is completely silent 

Its weird for me because here there is almost no silence even at night. Also for you people who know this and think its not really weird it is for me. for some reason

It is definitely a weird thing to think about. Space is only silent because gravity is very greedy and hogs all of the matter to itself in tight little balls millions of miles apart. If some matter such as air was able to stay dispersed evenly throughout the cosmos and properly transmit vibrations, many celestial objects would be deafeningly loud. The background noise of space would likely be a dull roar even at great distances from stars and other “noisy” bodies.

[KerikBalm]

13 minutes ago, lemon cup said:

It is definitely a weird thing to think about. Space is only silent because gravity is very greedy and hogs all of the matter to itself in tight little balls millions of miles apart. If some matter such as air was able to stay dispersed evenly throughout the cosmos and properly transmit vibrations, many celestial objects would be deafeningly loud.

Would it though? What would be the gas density if all matter in the observable universe were to be uniformly distributed.

Space is huge, but so are black holes, I can't even judge the order of magnitude of the orders of magnitude

On 12/4/2020 at 4:21 PM, KerikBalm said:

I missed one really obvious thing.... and a large reason why you'd never be living in a dense hydrogen atmosphere for long periods of time:

https://www.nap.edu/read/12032/chapter/9#152

Mixing hydrogen and oxygen in your habitat is a bad idea, even at just 4% oxygen (and 5 Bar!).

So that leaves Helium... which means that you will need a very big temperature differential to float.

Saturn is a similar situation.

Yea, you're not going outside while floating in gas gianst, I guess.

So I thought more about it, you would just have a large hot hydrogen envelope, and a smaller colony hanging below it.

At 10 bar, Saturn is a chilly 10 C, but just put on a coat.

Your colony atmosphere would be like 2% oxygen, 8% nitrogen, and 90% helium.

Gravity is below 1.1G, and you can survive in 10 bar... Although wind-chill factor is going to be higher because of the increased pressure... Maybe go a bit deeper, but if people have lived at 60 atmospheres for months, there is surely a place where you could comfortably go outside with just a breathing mask.

Don't expect to ever leave though

 

[cubinator]

3 hours ago, sir rocket said:

I don't think it would feel completely silent. Your brain would try to fill in sounds for the deprivation, causing a ringing. Note that this is from personal experience, not any scientific studies 

You would be able to hear such sounds as your breath, heartbeat, and digestive movements. You would also be able to hear noise from objects you touch. Apart from that, there would be no sound.

2 hours ago, KerikBalm said:

Would it though? What would be the gas density if all matter in the observable universe were to be uniformly distributed.

Not enough to hear - it would be more like a nebula through space. If there was 1 atmosphere between here and the sun, though, you'd need to wear earplugs.

[kerbiloid]

3 hours ago, KerikBalm said:

Your colony atmosphere would be like 2% oxygen, 8% nitrogen, and 90% helium.

They will be able to recognize Saturnian TV by funny voices.

***

When you can live for millions of years and have planet-sized ears, the universe ambience sounding will make you mad by sonic waves in the interplanetary gas, and shockwaves here and there.

We just have small ears and short lifespan.

1 hour ago, cubinator said:

You would be able to hear such sounds as your breath, heartbeat, and digestive movements. You would also be able to hear noise from objects you touch. Apart from that, there would be no sound.

A week later even listen the voices right in the head and start talking to them.

Then arguing.

Then stop talking because they are silly.

Edited December 5, 2020 by kerbiloid

[paul_c]

The closest planet to Earth is.......Mercury. In fact, Mercury is the closest planet, to every other planet, once its all averaged out (think about it...)

The Nasa Mercury program......didn't go to Mercury.

The Saturn 5 rocket......didn't go to Saturn.

[Codraroll]

The total luminosity - power output - of the Sun is almost 4 * 10^26 Watts. That's a lot of power. But averaged over the Sun's volume, it's a mere 0.27 Watts/cubic meter. That's comparable to a compost heap.

[kerbiloid]

So... If make a compost heap of solar mass...

[AHHans]

3 hours ago, Codraroll said:

The total luminosity - power output - of the Sun is almost 4 * 10^26 Watts. That's a lot of power. But averaged over the Sun's volume, it's a mere 0.27 Watts/cubic meter. That's comparable to a compost heap.

Well, actually fusion only really occurs in the core of the sun. Which is only about the inner 20% - 25% of the solar radius. So with that the power density of the solar core is 20 - 35 Watts/cubic-meter. More than a compost heap (I think ), less than a camp fire.

(For comparison: a Chernobyl type reactor had a thermal power density of about 2 Mega-Watts/cubic-meter! )

1 hour ago, kerbiloid said:

So... If make a compost heap of solar mass...

Then it will probably rather quickly collapse into a white dwarf. You might get some nova-like explosions during the collapse when one or the other kind of fusion sets in. But I don't think there is enough hydrogen in your average compost heap to keep it on the main sequence - or any of the other usual stellar evolution steps - for any amount of time.

The really funny thing I noticed is that the average density of the sun is about the same as what I think the average density of a compost heap is. (1.4 g/ccm)

P.S. I actually made the same total solar volume vs. volume of the solar core mistake when preparing an exercise sheet for 1st year students. And then got corrected by the students. How embarrassing!

Edited December 10, 2020 by AHHans

[kerbiloid]

Unlikely this dwarf could be white...

[AHHans]

50 minutes ago, kerbiloid said:

Unlikely this dwarf could be white...

Oh! My desire to make a poop joke and my tendency to try to educate people are getting into a serious fight here.

[Terwin]

On 11/25/2020 at 9:58 PM, starcaptain said:

The main limiting factor of why we can't reproduce in space is that a lack of gravity [very likely] hampers the development of a proper cardiovascular structure for a human being. Without the pressure and resistance caused by gravity stresses, an infant's heart would be only strong enough to survive nominal and low-stress microgravity conditions. The physical stresses of being born would [very likely] be fatal.

Isn't the womb a fluid environment where the fetus is basically at neutral buoyancy until it is nearly fully grown(at which point is unable to move freely due to lack of space, I think).

Exactly how different is neutral buoyancy with a semi-random orientation from micro-gravity?  I would expect the two to be rather similar...

On 12/4/2020 at 4:34 AM, KerikBalm said:

You'd have to adjust the gas composition that you breathe, but it shouldn't be too different from scuba diving. At 40 meters below the ocean's surface, the pressure is already roughly 5 bar.

40 meters is the maximum depth for recreational scuba diving, and even approaching that depth is hazardous because the partial pressure of nitrogen at that depth starts to affect the mind(look up 'nitrogen narcosis').

I would not want to try living at that pressure.

[AHHans]

1 hour ago, Terwin said:

Exactly how different is neutral buoyancy with a semi-random orientation from micro-gravity?  I would expect the two to be rather similar...

You are still experiencing full gravity. E.g. if you are upright then the blood from your legs still need to work against gravity to get back to your heart. Also you have the fluid resistance that makes moving your body around harder - and thus trains your muscles.

[starcaptain]

Baking in microgravity works about 1/4 speed. Due to lack of convection, heat only works by radiation.

The first cookies baked in space took 45 minutes,  as well as almost half an hour to cool.

Worst of all,  the astronauts didn't get to eat them! The cookies had to be returned to earth for study!

[Terwin]

2 hours ago, AHHans said:

You are still experiencing full gravity. E.g. if you are upright then the blood from your legs still need to work against gravity to get back to your heart. Also you have the fluid resistance that makes moving your body around harder - and thus trains your muscles.

As far as I am aware, a baby need not spend any time in any particular orientation aside from just before birth, and will spent a lot of time in a fetal position, which minimizes gravitational differential.

Fluid resistance and fluid drag would be the same on earth or in microgravity.

[kerbiloid]

5 hours ago, starcaptain said:

The first cookies baked in space took 45 minutes,  as well as almost half an hour to cool.

Easy to forget, but hard to burn.

5 hours ago, starcaptain said:

Worst of all,  the astronauts didn't get to eat them! The cookies had to be returned to earth for study!

Based on these cookies cost,
"Your ISS browser anyway doesn't accept cookies, while here on the Earth we will eat it together with Screaming Eagle Cabernet 1992, $500,000 per bottle. Mwahahah, give all your cookies to us!"

Next time they will try again with candies.

***

Baby can't be growing up for 21 year inside.
So, whatever it experiences for the first ~9 months, then anyway faces the low gravity, so the skeleton and cardiovascular system growth will be under great pressure.

Edited December 11, 2020 by kerbiloid

[KerikBalm]

10 hours ago, Terwin said:

40 meters is the maximum depth for recreational scuba diving, and even approaching that depth is hazardous because the partial pressure of nitrogen at that depth starts to affect the mind(look up 'nitrogen narcosis').

I would not want to try living at that pressure.

Yea, which is why the proportion of nitrogen would be lowered to about 8% at 10 bar.

I mean, you could remove it completely, but you'd want it to grow food. You could put a nitrogen containing fertilizer in the greenhouse soils, and just have a helium and O2 atmosphere in the colony

[Terwin]

9 hours ago, kerbiloid said:

Baby can't be growing up for 21 year inside.

So, whatever it experiences for the first ~9 months, then anyway faces the low gravity, so the skeleton and cardiovascular system growth will be under great pressure.

Agreed post-birth special care/activities would need to be undertaken to stress the body to ensure a sturdy enough development to allow survival in a higher-gravity environment(similar to how astronauts must exercise more in space to reduce muscle and bone loss, but more so)

The original supposition was that the child would be unable to survive the birth process without gravity to toughen it up during gestation, and that seemed less than plausible to me considering the gestational environment.

[AHHans]

16 hours ago, Terwin said:

As far as I am aware, a baby need not spend any time in any particular orientation aside from just before birth, and will spent a lot of time in a fetal position, which minimizes gravitational differential.

My post was meant as an answer to the general question about the differences between neutral buoyancy and micro gravity.

About the question of babies being born (or not) in space, there are some videos from Medlife Crisis: What If Babies Were Born In Space? A Doctor Explains, and Space Doctor Analyses Medicine In THE EXPANSE.

P.S. I just re-watched those two: the first is highly entertaining but doesn't really say anything about growing up in space, the second is more informative and mentions several issues of reproduction in microgravity but doesn't mention the pre-natal development of the cardiovascular system.

Edited December 11, 2020 by AHHans
added P.S.

[Nightside]

On 12/10/2020 at 8:05 AM, kerbiloid said:

So... If make a compost heap of solar mass...

...then you will need some very large worms.

Spoiler

 

Edited December 11, 2020 by Nightside

[starcaptain]

The Sun is no longer the most spherical object we know of. LIGO tried to observe the gravity waves emitted from known pulsars and verified that even though they spin at tremendous speed,  the variability of one side of a neutron star to the other is infinitesimal. We're talking nanometers or less of spheroidicity for solid objects many kilometers across,  which is far finer than the nebulous atmosphere of our Sun.

This may or may not be a wrench in the works of the idea of nuclear pasta, and is a subject of ongoing research. 

(Nuclear pasta is what some atomic configurations are called,  which are theorized to exist in netron star atmospheres.  At high levels, atoms  blob together,  forming nuclear gnocci. At mid levels,  these blobs become quite long,  becoming nuclear spaghetti.  At deeper levels,  the noodles form sheets all composed of many atoms  smeared together,  called nuclear lasagna. )

[kerbiloid]

So, this is where it lives!

[Codraroll]

On 12/10/2020 at 5:05 PM, kerbiloid said:

So... If make a compost heap of solar mass...

I think one of the general rules of thumb of the universe is "anything with the mass of a star becomes a star".

That's a slightly modified version of Randall Munroe's rule of electric heaters, coined during a discussion in the How To book on boiling rivers as a means to cross them without getting your feet wet: "any mass congregations of electric heaters, that combined output the same amount of heat as a lake of lava, will eventually become a lake of lava"

[kerbiloid]

6 hours ago, Codraroll said:

I think one of the general rules of thumb of the universe is "anything with the mass of a star becomes a star".

"If it looks like a star, shines like a star, smells like a star, it's a star."

[K^2]

On 12/11/2020 at 5:37 PM, starcaptain said:

Nuclear pasta is what some atomic configurations are called,  which are theorized to exist in netron star atmospheres.  At high levels, atoms  blob together,  forming nuclear gnocci. At mid levels,  these blobs become quite long,  becoming nuclear spaghetti.  At deeper levels,  the noodles form sheets all composed of many atoms  smeared together,  called nuclear lasagna.

Damn it, whose turn was it to make sure the scientists have been fed?

[JoeSchmuckatelli]

On 12/10/2020 at 11:05 AM, kerbiloid said:

So... If make a compost heap of solar mass...

You talk a lot of sh-

8o

Edited December 15, 2020 by JoeSchmuckatelli