What is nothing
Scientific Definitions of Nothing
Scientists do not have a single definition of nothing. There are several different definitions of what nothing is and lots of scientists disagree with each other on the scientific definition of nothing. Below are three general definitions. When working out a theory of the universe creating itself from nothing, most use some variation of the first one, empty space. When the religious community says the universe cannot be created from nothing, they are normally speaking of the last definition, no universe or laws of physics.
- Empty space - removing all the matter from space (ex. planets, stars, atoms, particles). This still leaves space ( or more correctly, spacetime), the laws of physics, and the vacuum of space still has some energy. This is the definition most scientists use when they say the universe was created from “nothing”.
- Empty space (or spacetime) in the lowest energy state possible - There is no matter, energy, radiation or spacetime ripples. Space (or spacetime) and the laws of physics still exist. The universe could not have been created from nothing using this definition.
- No universe (or spacetime) and no laws of physics - Physicists do not have a good definition for this state of “nothing”. There is now way to observe what is outside the universe or to know what would be with no universe. This is the state of “nothing” that most religious people claim when they say the universe cannot be created from nothing. Scientists cannot say if the universe could have been created from this definition of nothing because there are too many unknowns.
The Hartle-Hawking No Boundry Proposal
Stephen Hawking is one of the more popular scientists that has researched the beginning of the universe. He has worked with a few other scientists to come up with the Hartle-Hawking No Boundary Proposal. I do have a hard time understanding some of the concepts in this theory.
When Hawking has been asked about what came before the Big Bang, he has said that since time did not exist, it’s meaningless to ask what came before the Big Bang. He equates it to asking what is south of the South Pole because nothing is south of the South Pole.
- The infinitely small universe was rounded with no edge or boundary. Similar to how the earth has a finite size but since it is a sphere has no edge. Also since the universe is so small, current physics (Einstein’s theory of relativity) does not exist. So time does not exist at this phase of the universe, there is just 4 dimensional space (we currently have 3 dimensions) without time. Since time did not exists and the universe had no edge or boundary, there was no beginning to the universe.
- A key concept of the no boundary proposal is the Feynman’s sum-over-histories formulation of quantum theory. This states that a particle that moves from point A to point B takes all possible routes connecting A to B. Then each possible path (or history) is assigned a relative probability. The more straight forward paths are weighted higher than the more convoluted paths. This is called a wave function.
- The no boundary proposal is a wave function for the entire universe and describes all the possible options (or histories). It assigns probabilities to all the different histories of the universe, at least in theory. It’s far too complicated to calculate all the possible expansion paths of the universe so they had to drastically simplify the situation.
- Using the “bottom-up” method, which calculates the probability of our universe forming without the assumption that we exist, it predicts an empty universe with little inflation. In order to match our universe, you need a long period of inflation. To correct this, they came up with the “top-down” method. It adds the condition that we and the universe physically exist. With that condition added, the no boundary proposal predicts a long period of inflation.
- Not only does the “top-down” method predict a long period of inflation, but that inflation lasts eternally. Inflation in our universe only lasted for a finite amount of time so the theory says that there are multiple universes (a multiverse) and that inflation is moving from one universe to another since it is happening eternally.
- The multiverse also helps solve the problem of our universe being very rare according to the predictions. Since there are any number of universes, this helps account for us existing with such small odds because there are many universes in which we don’t exist. So there is nothing special or “fine-tuned” about our universe.
- For this theory to be true, inflation has to be true and inflation is an unproven theory at this point.
The Borde-Guth-Vilenkin Theory
This theory assumes our universe is a “closed” universe. A closed universe is shaped like a sphere (or ball) and has no edge. This means it’s a finite size. An open universe is flat like a sheet of paper and is infinite in size. Scientists still debate if our universe is open or closed.
- The energy of a closed universe is always zero. So that means there is always the same amount of negative energy as positive energy in the universe. The energy of matter is positive and the energy of gravity is negative. So by this theory, you do not violate the law of conservation of energy because the total amount of energy in the universe adds up to zero.
- This theory uses Quantum Creation which uses quantum mechanics. Basically as long as all the numbers add up to zero, then there is nothing to prevent a universe being created from nothing. And according to quantum mechanics, any process that is not forbidden by the conservation laws will happen with some probability.
- The most probable universe in this theory is the smallest universe with the highest vacuum energy. The high vacuum energy causes the universe to expand once it is formed.
- Quantum creation is a speculative hypothesis with no real way to test observationally.
- This theory implies a closed universe but all observations indicate our universe is flat. A flat universe is an open universe.
- The laws of physics already had to exist and there is no explanation for why or how they already existed.