Absolute zero

[greenrivet]

2 questions for somr help please:

1.Can temp go below absolute zero; if not why not. Is local space abs zero. Is all space, even outside this galaxy abs zero. If so, how is it known. ? Who said absolute zero is the lowest it. can go ?
2. I guess the pressure in space is zero ? If so , I guess it cannot go below zero because it would be sort of forced to make the universe smaller, not bigger with expansion. Just thinking about that, is it possible there is positive pressure in the universe ?. Or is all space zero pressure ?
Appreciate if answers are not too complicated, and .no maths thankyou.
Kind rgds

 

[Catastrophe]

Hi greenrivet

1. No, temperature cannot go below absolute zero. The way you can cool something is by treating it with something colder - so why can't you do that? Well to treat it with something colder, you would need to make that 'something;, which means that you would need to make that something colder - and so it goes on.

So why can't you get below 0 degrees K (I don't care, C and F are capitalised).
Well temperature corresponds to atoms/molecules jumping around. The more you heat them up - give them energy - the more that energy turns into heat. Conversely, if you cool them down, it takes away heat energy in the form of movement. So absolute zero is when they are lying 'dead' still. All you have at your disposal to cool them further are other 'dead' still molecules, so, of course, nothing happens.

For the same reason, you cannot ever actually reach 0 K since you cannot get anything colder to cool them with.

2. No, the pressure in space is not zero. But it is below the lowest pressure we can make in the laboratory. If you think about it, pressure is due to molecules jumping around like temperature. I know you said no equations - but please one teeny weeny itso ever so tiny one. For a gas there is an equation P x V = R x T
where R is a constant and T is temperature. So you can see that, for a gas, they are all related. If you seal gas in a container and heat it, V is constant, the volume of the container, so pressure is proportional to temperature. We know that. If you heat gas in a sealed container the pressure goes up.

Having said that, there is only a certain amount of gas, mostly hydrogen (H) and helium (He) because so much is taken up making stars. But if you have any amount of gas, it will have a pressure, and so it will move into lower pressure areas. So however much H and He are out there, they will spread out until the pressure is equalised. When all at the same pressure, there is no 'reason' to expand further. That would just make a lower pressure somewhere else.
So even though you might have only one gas molecule per cubic mile, or even a lot less, the pressure will never get totally absolutely down to zero.
Of course, the temperature in outer space (away from stars) is pretty cold, so the molecules don't have much energy to move around either.

Hope that helps, but please come back if you have any questions.

Best wishes,

Cat

 

[greenrivet]

That's great Cat, many thanks for the quick answer.
Kind regards

 

[Atlan0001]

2 questions for somr help please:

1.Can temp go below absolute zero; if not why not. Is local space abs zero. Is all space, even outside this galaxy abs zero. If so, how is it known. ? Who said absolute zero is the lowest it. can go ?
2. I guess the pressure in space is zero ? If so , I guess it cannot go below zero because it would be sort of forced to make the universe smaller, not bigger with expansion. Just thinking about that, is it possible there is positive pressure in the universe ?. Or is all space zero pressure ?
Appreciate if answers are not too complicated, and .no maths thankyou.
Kind rgds

Temperature cannot go below absolute zero because if you read on the internet what physicists in the know, know about absolute zero it can never be reached. There is a horizon of infinite / infinitesimal residing as a wall that blocks it from ever being reached. The closer we get to it the more we "spin our wheels", so to speak. And that spinning of wheels translates to the entities of superfluidity and superconductivity. Absolute zero possibly being the hyper extent mechanism of superfluidity and superconductivity.

Interesting that you asked "is local space abs zero"? According to the "observable universe" the absolute of the background non-local horizon of the universe (u) -- the Planck / BB horizon -- is as hot as hot can get. About 1.420 nonillion degrees centigrade from what I read. Absolute zero is everywhere finitely, relatively, local horizon. The Planck / BB temp is everywhere infinitely, non-relatively, non-local horizon. We, and the universe of stars and galaxies and matter and energy, exist in the radial horizon between the two horizon extremes of absolute resistance to flow and no resistance whatsoever to flow.

 

[greenrivet]

many thanks Atlan0101 much appreciated. kind rgds