To Be Determined

The world is brimming with symmetries.

This is, in part, because humans love to observe symmetries in things. Many evolutionary biologists theorize that at some point, we (as living creatures) evolved to associate this phenomena with health. We ate plants with symmetrical leaves and berries, we admired the symmetries in others faces, we survived for millennia (and still do) by recognizing patterns. It is arguable that symmetry is ingrained in us to be an aspect of some objective attractiveness. Or perhaps we simply avoid asymmetry like the plague, evolutionarily speaking.

Symmetry does not seem to be entirely on us, though. The past few centuries of rigorous scientific exploration have revealed symmetries buried deep within nature, in the laws of biology and physics. There is symmetry under spatial transformation, which gives us conservation of momentum. There is symmetry under rotations which gives us conservation of angular momentum. There is symmetry under time translation implies conservation of energy. These are established by Noether’s theorem, a brilliant German mathematician from the late 19th century.

If you want to get crazy, there is Charge Parity Time symmetry, a fundamental law of physics that shows that a “mirror image” of the universe flipped in all three aspects would evolve identical to ours. Reflect all positions, change matter to antimatter, and invert time (reverse momentum) and the universe would evolve the exact same.

But I digress.

It’s fun to think about symmetries and the logical consistency that they bring because it almost gets easy to imagine that there is simply some fundamental, logical truth to things and that is why they are. Symmetry is consistency and consistency is truth.

But probably not. Here are two of the coolest asymmetries that currently stand as some of the greatest natural phenomena unbridled by our scientific “truth.”

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The universe does not obey time translation symmetry, which means energy actually isn’t conserved.

Crazy? True? Yes and yes. In Special Relativity, spacetime is infinite and highly symmetric, under Lorentz transformations. However, in General Relativity, which exhaustively explains relativistic effects for all gravitation and generalizes relativity, these symmetry transformations are conserved locally. This means that coordinate transformations can be coordinate-dependent. This is key: now there is no globally defined notion of energy conservation. When you do this for the entire universe, it’s either expanding or contracting.

We know it’s expanding.

Thus, we know the universe is breaking this symmetry in time translation and thus it is fundamentally asymmetric. This also means that there is a preferred coordinate system for the universe, what physics calls comoving coordinates. A particle moving relative to this preferred eventually loses momentum and come to rest. Where does the energy go?

Away.

Energy is still conserved locally though, as the energy moving out of and into the particle is conserved (if there was any). But the total amount of energy for the particle decreases.

You can find other instances of spontaneous symmetry breaking like this, many bosons like the Higgs are theorized to do this. There is no reason to think that the universe plays nicely with our laws.

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Life on Earth only exists in single-handed form, something called homochirality. Well. Almost. Regardless, the enantiomeric imbalance of life is a strange phenomena, and quite possibly one of the reasons it exists at all.

Asymmetric carbon atoms cause this chirality, as when carbon compounds form, they can effectively have a mirror image. When one synthesizes chemicals without intervention, much in the way life is theorized to have formed, an almost equal mixture of handed molecules forms.

When did the so-called “mirror break,” then, in the primordial soup?

Long story short, it seems to be thermodynamically favorable, due to crystallization processes for carbon compounds and the blocking of RNA polymerization that occurs in life.

One of coolest aspects of this asymmetry is that it seems to be capable of reducing entropic barriers in the formation of large organizations of complex molecules. As life is akin to the swirls of cream in a coffee cup in a mixing universe, this homochirality then makes almost perfect sense.

The mystery is if the handed-ness that life has was a coin-toss. Or perhaps there was some catalyst that broke the mirror. It is theorized that another asymmetry in the universe, commonly electroweak interaction, played a role in deterministically swaying life to be born of enantiomeric excess. There is evidence that suggests that interstellar dust has chiral mechanisms as well. But if we buy into the thermodynamic amplification theory, chance could play a huge role, as the likelihood of equal counts enantiometers in large compounds or organizations is exceedingly (10^-10) low.

One this is certain: chirality seems to predate life. If it occurred before, we likely would be able to detect signs of extinct chirality.

The information storage feature that is chirality is, in a way, a precursor to life itself, perhaps I can even call this archaic asymmetry the most successful asymmetry there is.