
New Form of Atomic Nuclei and It Suggests Time Travel Is Impossible (2016) - elmar
https://futurism.com/new-form-of-atomic-nuclei-just-confirmed-and-it-suggests-time-travel-is-impossible/
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basicplus2
But which direction does this pear shaped atom point? Towards the big bang?

~~~
gus_massa
They usually point in a random (special) direction. If you put the atoms
inside a magnetic field they will point to the north pole or the south pole,
all of them will point in the same direction, but I'm not sure which one.

The idea is that if see a film of the universe with the time in reverse, the
laws will be exactly the same. You will notice some global problems, like an
egg getting magically rebuild after it is scattered on a wall. But if you look
at each particle individually you will not notice anything strange.

This is called the T symmetry.
[https://en.wikipedia.org/wiki/T-symmetry](https://en.wikipedia.org/wiki/T-symmetry)

The problem is that the T symmetry is not a real symmetry. There are some tiny
details that are different when you look carefully. This is totally not
related to the broken egg problem. Just ignore the eggs.

I'm not sure now about the details, but IIRC when you reverse the velocities
of all the particles, then the electromagnets have the current flowing in the
other direction. But the atom nuclei have a tiny magnetic moment, due to spin,
that is not reversed. So [mmm] and then [mmm] so it's obvious that all the
atoms nuclei have to be ellipsoids, not have a pear shape. They have to be
symmetric in the direction of the spin.

They apparently measured (indirectly) the shape of some atom nuclei and they
have a pear shape, so it's a new experimental prove that the T symmetry is
broken. IIRC all the previous proof were more indirect.

If you see the film of the universe in the reverse direction, you can look
carefully at this atoms inside an electromagnet and see that the pointy part
of the pear is in the wrong direction. (Assuming they hide all the eggs and
other objects than can give you an easier clue.)

This operation T is called time reversal, and it gives a lot of useful
information about systems where the broken part of the symmetry is negligible.
In particular if you want to calculate the properties of a small molecule, you
can use this property to reduce a lot the amount of calculations.

You may be wondering how is this related to Time Travel ... me too. Probably
is the linkbait version of Time Reversal, that is a too nice name for a simple
operation.

------
DrScump
(June 2016)

~~~
elmar
Updated title :)

