A Physics Question

[ShadowKatt]

So I was having a discussion with some friends about Absolute Zero(Zero degrees Kelvin), and I commented about how AWESOME it would be to see an atom a 0 degrees kelvin when all motion stopped and the elctrons were suspended in their orbits, and that got me thinking...

Would they be stopped?

At 0K, all energy has ceased, including kinetic energy, so the electrons have ceased moving and all momentum is gone. However electrons, like planets and moons, exist in a balance. The force trying to throw them out(forward momentum) is equal to that trying to pull them in (magnetism and the nuclear forces). So if you stopped the momentum, then the attrative forces would pull the electron in. The electrons fuse with the protons and form neutrons, which would undoubtably release energy, and therefore raise the temperature.

But if the temperature is at 0K, and all energy has ceased, how can there be the kinetic energy for the electrons to move towards the center? Such a movement would generate energy and thus raise the temperature as well.

So, here's the big question, given the nuclear forces involved, is 0 Kelvin an attainable temperture or is it a theoretical construct? And if it is real, what happens to atom chilled to 0 Kelvin?

 

[Trivun]

I think it's simply a theoretical concept, much like the concept of infinity in maths. Useful, and you can use it to prove all sorts of things, but impossible to actually achieve in real terms, physically speaking (I just finished a maths degree, if you wondered about the comparison). Thing is, the centre part of the atom, the nucleus, is where gravitons are found (the sub-elementary particle responsible for gravitational force). So that would still attract, no matter how tiny the force, the electrons, to the centre of the atom, causing kinetic energy whether the electron was to continue its orbit or simply 'fall' to the atom's core. Thus the temperature would still be raised, by a tiny miniscule near-undetectable amount, and thus we wouldn't truly have absolute zero...

 

[Melon Hunter]

Won't happen, I'm afraid. The 3rd Law of Thermodynamics indirectly states you cannot reduce the temperature of an atom to Absolute Zero. In any case, the kinetic energy refers to the vibration of the atom due to thermal energy. Electrons aren't actually little balls whizzing around a nucleus; they're a weird mix between waves and particles and can only exist at certain distances away from the nucleus. So even if the atom did hit 0K, the electrons would continue to 'orbit' the nucleus.

 

[FalloutJack]

The answer is that science is not an exact science, per se. It is as close an understanding of the universe as we can get within the limits of our abilities. The rule has exceptions and the measurements are not precise in the same way that pi doesn't end.

 

[Lukeje]

So I was having a discussion with some friends about Absolute Zero(Zero degrees Kelvin), and I commented about how AWESOME it would be to see an atom a 0 degrees kelvin when all motion stopped and the elctrons were suspended in their orbits, and that got me thinking...

Would they be stopped?

At 0K, all energy has ceased, including kinetic energy, so the electrons have ceased moving and all momentum is gone. However electrons, like planets and moons, exist in a balance. The force trying to throw them out(forward momentum) is equal to that trying to pull them in (magnetism and the nuclear forces). So if you stopped the momentum, then the attrative forces would pull the electron in. The electrons fuse with the protons and form neutrons, which would undoubtably release energy, and therefore raise the temperature.

But if the temperature is at 0K, and all energy has ceased, how can there be the kinetic energy for the electrons to move towards the center? Such a movement would generate energy and thus raise the temperature as well.

So, here's the big question, given the nuclear forces involved, is 0 Kelvin an attainable temperture or is it a theoretical construct? And if it is real, what happens to atom chilled to 0 Kelvin?

Have you heard of Heisenberg's Uncertainty Principle? Your problem is that you are trying to view quantum mechanics from a classical perspective.

Also, no. Absolute zero is not physically realisable (if one point of space is at absolute zero then the transfer of heat means that every other point also has to be at absolute zero).

Edit: I should also point out that you can compute the electronic energy levels of an atom at 0 K relatively easily.

 

[nicksdrago0]

Assuming that the atom hit 0K, and had no possible external forces to give it heat, the magnetism of the atom would stop as well as the electrons movement. Thus a balance would still exist, but rather a case of no forces whatsoever rather than forces balancing each other out.

I actually recently asked my physics teacher the same thing, and thats the gist of what he gave me.

Edit: also gents, his asking what would happen IF an atom hit absolute zero. Yes its only a theory that from our current point of view seems literally impossible to form anywhere in the universe, but his not asking how to make it possible. His asking what would happen if it was possible to create.

 

[ShadowKatt]

So I was having a discussion with some friends about Absolute Zero(Zero degrees Kelvin), and I commented about how AWESOME it would be to see an atom a 0 degrees kelvin when all motion stopped and the elctrons were suspended in their orbits, and that got me thinking...

Would they be stopped?

At 0K, all energy has ceased, including kinetic energy, so the electrons have ceased moving and all momentum is gone. However electrons, like planets and moons, exist in a balance. The force trying to throw them out(forward momentum) is equal to that trying to pull them in (magnetism and the nuclear forces). So if you stopped the momentum, then the attrative forces would pull the electron in. The electrons fuse with the protons and form neutrons, which would undoubtably release energy, and therefore raise the temperature.

But if the temperature is at 0K, and all energy has ceased, how can there be the kinetic energy for the electrons to move towards the center? Such a movement would generate energy and thus raise the temperature as well.

So, here's the big question, given the nuclear forces involved, is 0 Kelvin an attainable temperture or is it a theoretical construct? And if it is real, what happens to atom chilled to 0 Kelvin?

Have you heard of Heisenberg's Uncertainty Principle? Your problem is that you are trying to view quantum mechanics from a classical perspective.

Also, no. Absolute zero is not physically realisable (if one point of space is at absolute zero then the transfer of heat means that every other point also has to be at absolute zero).

I have heard of Heisenbergs uncertainty principle, however I have not researched it. I'm not a physicist, physics is just a hobby so I don't have a lot of research into it.

 

[spacewalker]

arent electrons basicly lighning?
i dont think absolute zero would suspend forces like gravity or magnetism, both wich could affect the atom in some way.

 

[Amphoteric]

It is absolutely impossible to obtain 0K. You can only get it down to a millionth of a millionth of a degree above 0K.

You cannot know the exact position and velocity of an electron.

Asking what would happen at 0K is like what happened before the Big bang. It is not a coherent question.

 

[MoNKeyYy]

Well absolute zero has never been observed or obtained, so yes it is a theoretical principle. It's derived from the observation of trends mostly in gases and then a hypothetical continuation of these trends. It's scientific conjecture, really. But if hypothetically it were to be reached I guess the assumption is that intramolecular forces and atomic nuclear forces aren't taken into account with the calculation of said energy. Or maybe absolute zero is like a 4-dimentional object in our 3-dimentional universe, or a tangent line on a circle; only able to exist for a brief moment.

 

[LostTimeLady]

I have to agree with people above, the problem with absolute zero is that it is unobtainable physically.
I think 0 Kelvin probably needs to be viewed in the same way as working 'in the limit', the theortical edge where small things tend towards zero and large things tend towards infinity. It makes things nice and neat and seems to have worked so for for maths and science for the past few years! (Understatement for comic effect).

 

[Lukeje]

I have heard of Heisenbergs uncertainty principle, however I have not researched it. I'm not a physicist, physics is just a hobby so I don't have a lot of research into it.

Basically, you're asking the wrong question. The question is not `If an atom was at 0 K, would all the electrons have spiralled into the nucleus?' but rather `Why don't the electrons just spiral into the nucleus at any temperature?'. It would always be energetically favourable to do so from a classical mechanics perspective. In quantum mechanics, however, the state of the electron being at the nucleus (and thus localised at a single point) is associated with an infinitely large momentum. The electron is thus propelled away from the nucleus. There is therefore a kinetic `ground state' energy, even at 0 K (`zero point energy').

 

[Nimcha]

Even if 0K was feasable, at that kind of level quantum mechanics take over and nothing's sure anymore.

 

[Lazy Kitty]

But if the temperature is at 0K, and all energy has ceased, how can there be the kinetic energy for the electrons to move towards the center? Such a movement would generate energy and thus raise the temperature as well.

The electrons would have already reached the atom before it got to 0K.

To reach something like that you'd need a closed space (like the universe) and everything would have to be at 0K.

Energy wouldn't really have ceased but be stored as potential energy. (Since energy can't be destroyed)
Everything (all mass and potential energy and anything else if there is anything else, possibly as something even more basic) would be stored in a single point that takes up no space.
Due to too much strain of everything being in one point, this situation can't be sustained, so it would explode (think Big Bang), thus no longer being at 0K.

 

[Cavehybrid]

i believe the rules don't apply due to the idea ur mentioned. If the one force stopped it would cause a reaction creting heat and cancelling out the no energy idea. I dunno ask someone smarter

 

[The_root_of_all_evil]

So, here's the big question, given the nuclear forces involved, is 0 Kelvin an attainable temperture or is it a theoretical construct? And if it is real, what happens to atom chilled to 0 Kelvin?

Purely theoretical, due to the third law of thermodynamics.

The third law of thermodynamics concerns the entropy of a perfect crystal at absolute zero temperature, and implies that it is impossible to cool a system to exactly absolute zero, or, equivalently, that perpetual motion machines of the third kind are impossible.

Basically, to cool something to a temperature, you need a coolant lower than that temperature. Or the ability to destroy all potential energy within. Which is impossible under current known conditions. So it counts as purely theoretical. There may be ways of doing it, but they're not within our understanding of physics at the moment.

 

[DFish]

Your problem here is the "electrons orbiting" idea. Electrons do not orbit the nucleus in the same way that the Earth orbits the sun. Like most of the physics you get taught at school it's a useful way of describing the situation that's actually completely wrong.

If electrons really were moving in little circles around the nucleii they would almost immediately lose their kinetic energy through Bremsstrahlung.

An electron orbital is a probability distribution around the nucleus describing where you are likely to find the electron if you try to measure its position. However - quantum physics being what it is - the electron does not have a definite position until that measurement is made.

I don't think (but I'm not sure on this point) that the shape of the orbital is in any way affected by the temperature of the atom.

Also, as a number of people have pointed out you cannot actually cool something to absolute zero, although you can get pretty close.

(PhD particle physicist - just don't ask me what "outside" looks like)

 

[Twilight_guy]

0K is when all heat has left an atom due to its kinetic energy being 0. If an elements hit 0K its electrons would be unaffected. For one, 0K describes the energy of the atom not the electrons its like saying if the sun stop s would the planets also stop. Of course not. Stoping your frame of reference does not affect the internal components. Aside from that, Electrons don't move due do to kinetic energy. Unlike planets orbiting a sun electrons do not move in orbits or paths, they move in a more chaotic motion that is only mapped by probability fields. Kinetic energy does not cause electrons to move and thus they would continue to move regardless of if the atom loses all energy. This is all theoretical of course though since energy and matter are the same thing and in order to have 0 energy an object must also have 0 mass and thus not really be an object anyways.

 

[nicksdrago0]

Asking what would happen at 0K is like what happened before the Big bang. It is not a coherent question.

You see, that statement feels awfully anti-scientific to me. Science has always been a profession not of "What can we do" but rather "What does that do". Whilst other trades and professions aim to make something useful such as a mechanic or a manufacturer, the very basics of science is looking at what is considered impossible, and find a way to prove it possible. A great example of this is the shape of the earth and its position in the universe-people scoffed back then at the idea that the earth was a sphere, or wasnt in the centre of our galaxy. It was as you said, not a coherent question.

In the world of science, nothing is impossible to try and figure out. Being curious simply allows us to look at something in a different way.

 

[MolotoK]

Electrons aren't actually little balls whizzing around a nucleus

This is probably the most important sentence in this thread.

The models we use to understand the universe are meant to explain certain observable phenomena and do not necessarily correspond with reality.