Bose-Einsteins Condesation?

Question

Hi
I am a Physics student and recently read about Bose-Einstein condensation. A couple of questions came to me that you might be able to answer.
1. If an object approaches absolute zero will it gradualy start to disappear due to the fat that there will be a reduced number of photon emisions due to reduced transitions to different energy levels.
2. Does an object have a reduced or no mass at or approaching absolute zero. Does this mean that hotter objects have greater mass than cold objects.

Answers to these questions would be much appreciated.

Many thanks

dba

My thinking about mass is that an objects mass is related to the kinetic energy of the atoms that make up the object. If the atoms are at or near absolute zero they will have less kinetic energy and therefore the object will have less mass.

Answer 1

nope.
1. it wont become invisible, you can still observe it
2. errm no (?!)
(did you read that about them somewhere? it sounds interesting if you did...)

i think there's a lot more interesting things about BECs than you've asked about... keep on reading!

--
oh ok, no they should still have their normal rest mass
i thought you might have read about a new wonderful-weird quantum effect!

Answer 2

1. You are sort of right and sort of wrong. The black body radiation will decrease. This effects both the number and frequency of the photons. But then again, your eyes don't see at these frequencies.

(Nor do your eyes see the black body radiation for typical earth stuff which is all in the infared -- unless it starts getting red hot like fire, lava, or a kitchen stove. The radiation given off by the BEC will be comparable to the Cosmic Background Radiation.).

Just like any other object, if the stuff reflects light, you would still see it if you shine a light on it. (And if it absorbs light, bye-bye conensate.)

2. Yes, it would have less mass, E=mc^2, remove heat energy and you remove mass. But then again a hot cup of coffee weighs more than a cold cup of coffee -- but we have nothing sensitive enough to measure the difference.

Answer 3

(1) If you're trying to get something close to absolute zero, *stop shining light on it!!!*

(2) Um, no. Where would you get such an idea?

Answer 4

No, Jesus mentioned the 1st component and then He died and then God mentioned "it is not time yet" and then Jesus got here decrease back to existence and hung around slightly and mentioned the 2nd component and died and God mentioned "it is not time yet" and Jesus got here decrease back to existence and mentioned the third component