New physics discovery could make time travel impossible
To back up a little: The reason time travel should be possible is because in many cases, the laws of physics seem to favor symmetry in space-time, right down to the shape of atomic nuclei.
But a newly discovered, pear-shaped atomic nucleus might be literally pointing to the future – and why it always exists ahead of us, instead of in all directions.
Think of it this way: In space, west is always west – but it’s relatively easy to change your orientation so that west can be behind or in front of you.
A longstanding questions is why we can’t do that with time. Are our own biological shortcomings to blame? Or is the inexorable forward march an embedded feature of the universe?
The lopsidedness of this nuclei suggests that it might be the latter.
Many of the laws of physics are what scientists call “time reversible,” meaning that it doesn’t matter if they play out going forward or backwards. This tracks with the standard idea in physics that space-time is symmetrical.
But in reality, time doesn’t feel symmetrical. It moves along the direction a metaphorical “time arrow” that points to the future, and to entropy.
Entropy is lopsided – nature seems only to move toward disorder from order, not in the other direction. (Though a universe where time mirrored ours would see the opposite effect, moving inexorably from disorder to order, and perhaps even toward the Big Bang.)
This lopsided little nucleus is pointing toward something, and it seems to be the direction of time itself. One of the discoverers of the nucleus, Marcus Scheck, told the BBC that the atom’s shape indicates “we will always travel from past to present.”