The new realities shown by Einstein
Based on Newton, things fall and planets turn because of the force of gravity. How does this force get exerted between two objects, we didn’t know. Space for him was just an empty container.
After Newton, James Maxwell and Michael Faraday came up with the idea of the electromagnetic field. Its applications were tangible and were used by Einsteins’s father as an engineer. Einstein was drawn by this idea, and he thought that gravity must be carried by a field similar to the electromagnetic one: a gravitational field.
With a stroke of genius, he theorized that space is the gravitational field. Space is no longer an empty container. It is now matter. Matter that bends, expands, and contracts. The sun’s weight bends space. Earth is no longer going around the sun in an empty container because of the inexplicable force of gravity. The earth is simply rolling in the curved space. Once a big enough star runs out of fuel, it bends space so much that it forms an actual hole. A black hole.
Our star, the Sun, would have to be at least 20 times bigger for it to become a black hole once it runs out of fuel (hydrogen).
Einstein also prophesized that time curves too. Time passes quicker for someone living on a mountain than his twin sibling living at sea level.
The German physicist, Max Planck, imagined that energy was divided into small packets of quanta. For him, it was a trick of calculation. The math worked but he didn’t understand why. It was Einstein who understood that light was physically made of these divided packets (photons). This isn’t a theoretical trick that works mathematically. It has become a reality. Light is no longer continuous in our understanding.
Planck conceived the theory. Einstein developed it. Now Bohr comes to push it to the next level.
Bohr introduced the quantum leaps: an electron can only jump between atomic orbits while gaining or losing a photon. Then Heisenberg, with a seemingly absurd view, explained how electrons don’t exist unless they interact with something. They materialize (exist), only when we interact with them. Einstein objected to this view because he thought that there has to be an objective reality: Something doesn’t exist because we interact with it. It just exists.
The history of our understanding of the universe
The simplest understanding we had was that we’re on the earth and came to understand that the earth is surrounded by the sky. Earth however was just a rock. Parmenides or Pythagoras realized then that the earth was actually a sphere. Aristotle confirmed it. Earth is now a sphere and celestial objects orbit it. Earth was still the center of the universe. in our understanding. It was Nicolaus Copernicus who shifted the center from the earth to the sun. Then, with better tools, we had the ability to see a wider universe where the sun is just a star among one hundred billion stars. We now see the galaxy. With even better tools, we unlocked the ability to see multiple galaxies.
“It is estimated that there are between 200 billion (2×1011) to 2 trillion galaxies in the observable universe” Wikipedia
Then, thanks to Einstein, we understood that this universe is a vast sea of waves. It started as a dense hot universe that exploded, expanded, and still is expanding.
Light is made of photons. Everything else is made of atoms. Each atom is made of nuclei and electrons. A nuclei is made of protons and neutrons. Protons and neutrons are made of smaller entities called ‘quarks’ which are glued by ‘gluons’. We also discovered other small elements called ‘Higgs bosons’. But they’re very few. These particles behave within the rules of absurd quantum mechanics. They are vibrations between existence and non-existence.
General relativity and quantum mechanics are the two greatest theories that explain how the world works. They both work experimentally but contradict each other. This contradiction offers an opportunity for a new theory to combine the two and offer simpler more cohesive explanations. Loop gravity is one of these promising theories that try to solve this issue. Space, based on this theory, is made of grains called ‘loops’. But there’s another astonishing hypothesis. Before the Big Bang, our universe was expanding until it bounced back to form a hot dense universe. It’s a loop. A repeating process of expansion, bounce, and then explosion.
Heat, probability and time
Heat moves from hot things to cold things with a very high probability. It doesn’t mean that it’s impossible for heat to move the other way around. But it’s extremely improbable. This probability with which we judge heat direction is because of our lack of complete knowledge. We’d need to know every variable in play to predict it with certainty. But we don’t. So the best thing is to judge using the variables we know. The result is a very reliable probability, yet not a certainty.
Another two weird ideas from this chapter: Heat also is what separates the present from the future. Time seems to be an illusion.