What would a substance at absolute zero look like?

29 November 2009

Question

What would a substance at absolute zero look like?

Answer

Dave - I see no particular reason why it would look any different to how it would appear at any other temperature (below melting point). If its staying at absolute zero, especially if you can look at it and you're shining light on it, then it's not absorbing very much energy, because as soon as you shine some light on it, and if any of the light was absorbed, then its going to get hotter than absolute zero. But I've seen very, very cold substances down to sort of minus 270-odd and they look pretty much like other substances.Chris - Wouldn't the pure act of looking at them, visualizing them, wouldn't that put some energy and so it couldn't be at absolute zero anyway?Dave - Yes. Essentially, if you're shining light on them, you're going to give them energy and you're going to heat them up. And that said, it could be transparent, so the only one thing you could look at and keep at absolute zero will be transparent but it's not to say that all things at absolute zero are transparent. Not that you can ever get there!

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