Why the Night Sky is Black and Beauty in Physics
Michio Kaku breaks down recent discoveries about string theory, the origin of the universe, and other cool facts about our world.
Ever wonder why the night sky is black? Sure, when we turn away from our sun, we face billions of others. The answer to why the night sky is black is more interesting than light diffracting over vast distances. Michio Kaku gives the answer in The God Equation:
“…the night sky is black because the universe has a finite age. We do not receive light from the infinite past, which would make the night sky white, because the universe never had an infinite past. This means that telescopes peering at the farthest stars will eventually reach the blackness of the Big Bang itself.”
The God Equation is an update to what we know about string theory and answers to common questions about space.
He also addresses criticism from another prominent physicist — Sabine Hossenfelder. In her book Lost in Math, she argues that physicists’ overreliance on beauty has kept us from discovering how quantum mechanics really work and how the universe really began. Kaku is among the types of scientists she’s criticizing.
Kaku’s response elevates this book from a pop science book to a continuing conversation about how to approach the most profound questions scientists can ponder.
Are String Theorists Lost in Math?
In Lost in Math, Hossenfelder argued that the strangeness of quantum theory and parallel universes comes from an over-emphasis on making equations “pretty.” The math behind multiverses may work, but it defies what we know about the laws of reality. Kaku quotes her:
“Beautiful theories have been ruled out in the hundreds, theories about unified forces and new particles and additional symmetries and other universes. All these theories were wrong, wrong wrong. Relying on beauty is clearly not a successful strategy.”
For example, one type of symmetry, parity, was disproven despite its neat mathematical solution. Hossenfelder knows of many other theories with pretty math that didn’t survive contact with reality.
While Kaku finds some value in Hossenfelder’s criticism, he has found value in symmetrical math equations:
“…one has to realize that aspects of string theory like supersymmetry are not useless and devoid of physical applications. Although evidence for supersymmetry has not yet been found, it has proven to be essential in eliminating many of the defects within the quantum theory. Supersymmetry, by cancelling bosons against fermioins, enables us to solve a long-standing problem, eliminating the divergences that plague quantum gravity.”
Kaku doesn’t substitute math for physical observations. He’s clear-eyed about the fact that supersymmetry hasn’t been proven, but he also confronts the parts of reality that must be explained by scientific theory.
As good as the accessible information about the universe is in this book, the ongoing dialogue between physicists is even better. It’s a rare look at the scientific discussion in real time and worth the quick read to see.
Kaku on Why There’s Something Rather than Nothing
Like all physicists, Kaku must confront the question of why there is something rather than nothing. Physicists who study space and time have a different definition of “nothing” from the rest of us. Empty space really contains quantum fluctuations, which Kaku describes in clearer terms:
“[Stephen] Hawking, as we saw, called this the space-time foam — that is, a foam of tiny bubble universes continually popping up and disappearing back into the vacuum. We never see this space-time foam, because each bubble is much tinier than any atom. But once in a while, one of these bubbles does not disappear back into the vacuum but continues to expand, until it inflates and creates an entire universe.”
Matter and antimatter pairs are constantly “jumping out of the vacuum and then collapsing back into the vacuum.” Empty space at the molecular level is full of activity at the quantum level.
Potential life is brimming all around us. Only a few people become well-studied enough to understand its origins.
Lucky for us, those people write good books.