Astronomy Picture of the Day 2-19-03

NASA ^ | 2-19-03 | Robert Nemiroff and Jerry Bonnell

[petuniasevan]

Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2003 February 19

Pauli Exclusion Principle: Why You Don't Implode
Credit & Copyright: Andrew Truscott & Randall Hulet (Rice U.)

Explanation: Why doesn't matter just bunch up? The same principle that keeps neutron stars and white dwarf stars from imploding also keeps people from imploding and makes normal matter mostly empty space. The observed reason is known as the Pauli Exclusion Principle. The principle states that identical fermions -- one type of fundamental matter -- cannot be in the same place at the same time and with the same orientation. The other type of matter, bosons, do not have this property, as demonstrated clearly by recently created Bose-Einstein condensates. Recently, the Pauli Exclusion Principle was demonstrated graphically in the above picture of clouds of two isotopes of lithium -- the left cloud composed of bosons while the right cloud is composed of fermions. As temperature drops, the bosons bunch together, while the fermions better keep their distance. The reason why the Pauli Exclusion Principle is true and the physical limits of the principle are still unknown.

[petuniasevan]

Particle physics day! Do your brain stretching exercises before doing any hard thinking! ;-D

If you've never taken physics courses (or stayed at a Holiday Inn) you may find this stuff confusing.

That's okay; a lot of physics principles, especially quantum physics, seem counterintuitive.

Questions should be directed to the pros; I have only a rudimentary knowledge of physics.

Here's the info for the above image:

This figure shows two-dimensional false color images of lithium atom clouds. Lithium has two stable isotopes, one of which is a boson (lithium-7), the other of which is a fermion (lithium-6). Bosons and fermions are the two fundamental types of quantum particles found in nature, and are distinguished by their contrasting behavior when in the quantum regime. The atom clouds are shown at three different temperatures: 810, 510 and 240 nano-Kelvin. One nano-Kelvin is a billionth of a degree above absolute zero, which is -460 degrees Fahrenheit. As the temperature gets colder, one can see that the boson gas, shown on the left, coalesces into a compact cloud, while the size of the fermion gas stabilizes at a specific size. This illustrates the principle of Fermi degeneracy, in which the fermions cannot condense further, due to a law of quantum mechanics--the Pauli exclusion principle--that keeps identical fermions from occupying the same space at the same time. The same effect stabilizes white dwarf stars against collapse under their own gravitational attraction.

[petuniasevan]

[fnord]

bump and bookmark ... interesting post.

thanks for all you do :-)

[mikrofon]

The Pauli Exclusion Principle

"Accept no others"

(The physics always seems to make more sense after a few...)

Great find, as always!

[firewalk]

Thank you

[GodBlessRonaldReagan]

Good one! Thanks for the ping..

[MozartLover]

bump

[sistergoldenhair]

Thanks!

[Ernest_at_the_Beach]

Thanks for another interesting post!