[Quantumcat]

You can edit you posts by clicking on the little button that looks like a notepad and pencil

Am I dead? Am I alive? I'm both!

[tweener]

I don't think that electrons would fall into the nucleus even at 0 K.  I think the "lack of motion" only applies to the atoms and molecules, not the particles that make them up.  If the electrons stoppped, wouldn't they violate the wave equation and the uncertainty priniple?


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John

[qpan]

Well- if the electrons did not fall into the nucleus, the substance would not be at 0 K would it? If the electrons still have ke, would this not mean that the atom still had ke? The movement of a negative charge would surely incite movement in a positive charge as it would lose/ gain p.e.? This effect would certainly cause the temperature of the substance to rise as fluctuations in the positions of the electrons would incite the movement of all positive nuclei in the substance (please correct me if i am wrong!)

"I have great faith in fools; self-confidence my friends call it."
-Edgar Allan Poe

[qpan]

actually- also read this forum here:
http://www.physicsforums.com/showthread.php?s=&threadid=5618
- it does make sense as i suppose the electrons cannot fall into the nucleus as it is one of the reasons absolute zero is not attainable (violation of heisenberg's law of uncertainty). Also, as i said earlier, you would not be able to cool something to absolute zero due to requiring an energy gradient (so it also violates the law of thermodynamics).
----So our debate is purely theoretical but about something which is actually theoretically impossible!--------

"I have great faith in fools; self-confidence my friends call it."
-Edgar Allan Poe

[tweener]

I read the forum thread and I still don't see anyone saying that the electrons will fall into the nucleus, or that the atoms will decay in any way.  I think the one post mentioned different definitions of temperature, and that may be the crux of the matter - what does absolute zero really mean.  

I certainly don't know.


----
John

[qpan]

Hi tweener- i suppose this post from the forum is similar, although it says lowest electron orbital instead of electrons falling into nucleus, but then continues to go on about zero subatomic particle motion:
"Theoretically,

At Absolute zero all electronic motion ceases. All of the electrons in the atom will be in the lowest possible orbitals.

Zero motion of a subatomic particle violates Heisenberg Uncertainty Principle, so it is not possible to achieve this state."
So i suppose it wouldn't be possible for electrons to fall into the nucleus then! But if absolute zero is defined as the point of zero energy and not minimum energy, and i'm not sure which it is defined as, then at zero energy, electrons would have an extremely high chance of having fallen into the nucleus with an almost infinetessimal (but still possible) chance of being elsewhere, from +ve infinity to -ve infinity!

"I have great faith in fools; self-confidence my friends call it."
-Edgar Allan Poe

[Ylide]

gpan:  If I may make a correction, at 0 K, all atomic motion ceases.  The atoms are not moving (i.e. no translational, rotational, vibrational energy) and the electrons are in their lowest possible energy states...that doesn't mean the electrons themselves are not moving.  

Temperatures of one one-billionth of a Kelvin have been reached...if the motion of the electrons in their orbitals were slowed by temperature, we would have violated Heisenberg already, as the electrons would be practically immobile at that temperature.

Anyway, don't nuclear repulsive forces keep the electrons from falling into the nucleus?

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[qpan]

Nuclear repulsive forces only occur between baryons- such as protons and neutrons. Electrons are leptons and not under the effect of the strong force. At very low temperatures, electrons have a very small amount of enery and are therefore far more likely to be in the lowest orbital and extremely unlikely to be anywhere else, but under heisenberg's law, the electron does have a (very) small probability for being elsewhere.
What is was saying in my other post was that wouldn't electron motion incite vibrational/rotational motion in the nucleus or neibouring atoms?
I don't think electrons are slowed by temperature decrease, as that would imply electrons just orbited atoms instead of just having areas of high probability (orbitals) which they are likely to be. The less energy an atom has, the more the high probability regions of finding electons moves towards the nucleus, so either the limiting case is the high probability region moves into the nucleus or to somewhere close above the nucleus, depending on what definition of absolute zero you use.

"I have great faith in fools; self-confidence my friends call it."
-Edgar Allan Poe

[GlacierBlue]

I hope I'm getting this right, because its 11:47pm and I'm tired. Your saying that you don't think that electrons can fall out of orbit when the temperature reaches one billionth of a degree above K because every atomic structure must have something in one of its orbits? This would explain why there is still some temperature I guess? The thing Im a little foggy about though is the fact that they say that they have reached a temperature close to -1.0e8 K. How do you measure something that cold? Temperature is a measurement of how much k.e. something has and if you can measure something, that imparts energy right? Isn't there something in Heisenberg's Uncertanty Principle about the process of observing something changes it?

If the multi-verse is a real construct then in some universe Im your God.

[nandakumar]

hi

  both the planes will reach their destination at the same time. if the wind speed is equal, or nil, efficiency of the aircraft is equal.

This is because of the rotation of the atmosphere with the earth. it has no effect on the aircraft or the vehicle on the ground. They travael at the same speed unless and until you have local problems.

What you are thinking is that if you place the aircraft above, you will your destination in the western side. I too have thought  about this but it sounds different.

i think now your doubt is cleared.

hi iam a student of geology and currently doing my post graduate degree in remotesensing

[GlacierBlue]

Your post didnt clear up much. I had a hard time understanding you. Is english you first language? I thought that it was odd that you are doing your graduate work on remote sensing. What type of college offers a degree program in ESP? If my memory is correct, remote sensing is like out of body stuff, correct?

If the multi-verse is a real construct then in some universe Im your God.

[Stephbaker]

If you threw a ball from a moving car, it would travel with the car for a bit before gravity pulled it down....momentum.
If you pulled the chair out from under someone as they were sitting down, they would miss the chair and bust their a$$....deviance.

Now, my belief is that traveling westward would be faster. There's not enough momentum from the rotation of the earth to make a difference either way. However, the earth would move enough that a certain point (chair) would be moved from under the plane (a$$). So, I would speculate that west would be faster. (Not counting time changes)
But, my mind is now debating with itself. Great. I know it doesn't take much, but now I'm confused. Thanks alot!

Welcome to the forum, Mawea.

Wow, this is the best answer! Thanks, man

[Janus]

If you threw a ball from a moving car, it would travel with the car for a bit before gravity pulled it down....momentum.
If you pulled the chair out from under someone as they were sitting down, they would miss the chair and bust their a$$....deviance.

Now, my belief is that traveling westward would be faster. There's not enough momentum from the rotation of the earth to make a difference either way. However, the earth would move enough that a certain point (chair) would be moved from under the plane (a$$). So, I would speculate that west would be faster. (Not counting time changes)
But, my mind is now debating with itself. Great. I know it doesn't take much, but now I'm confused. Thanks alot!

Welcome to the forum, Mawea.

Wow, this is the best answer! Thanks, man

Except for the fact that it is wrong.

[Petrochemicals]

So is the proposed plan for future air travel involving hopping up into near-space, sitting there a little while as the earth turns beneath you, and then landing in the right place, at all feasible ?

Chris

"I never forget a face, but in your case I'll make an exception"
 - Groucho Marx

Just like concorde, robot butlers, moon bases etc. Such a shame these things dont come to fruition.

[Janus]

So is the proposed plan for future air travel involving hopping up into near-space, sitting there a little while as the earth turns beneath you, and then landing in the right place, at all feasible ?

Chris

"I never forget a face, but in your case I'll make an exception"
 - Groucho Marx

Just like concorde, robot butlers, moon bases etc. Such a shame these things dont come to fruition.

It would be a extremely inefficient means of travel.  When you launch your rocket upwards, it would still be carrying momentum from the Earth's rotation.  Any drift relative to the ground would be the result of Coriolis effect. If you went up 300 km, this difference works out to be ~ 20 m/sec relative to the ground, which is  72 kph or 45 mph as a rough estimate.* To reach that 300 km altitude, you would have to launch your rocket at over 2.5 km/sec, and if you it to stay there for any length of time, you would be burning fuel to "hover".    Pretty damn wasteful, if you ask me.

* to work out exactly what the effective ground velocity would be over the course of any "flight" would require delving into orbital mechanics.