We don’t know what was there before the beginning of the Universe.
There, that answered the first question! But wait, there is more …
Physics deals with the laws of the Universe we live in and so its knowledge has the same boundaries as the Universe itself, both in time and in space. Anything outside, before or after the Universe becomes metaphysics: Abstract theories that are out of our reach to measure, proof or experiment on.
So in practice, we don’t know if there was nothing before the beginning of the universe or if there was something (else). But it’s a kind of now knowing, where we can only speculate forever, just like asking does an omnipotent God exist? Not for physics to answer.
Although … that doesn’t really stop some physicists from trying, among those Brian Cox, who has theories about the universe, in reality, being part of a bigger multiverse based on observations about the structure of our universe or Hugh Everett III, who wrote his thesis about his theory in the Many World Interpretation of quantum physics, back in the 1950s.
Since the Universe in time and space is the only reality that we know to exist, and anything outside, before or after does not make any sense in term of our reality, we can, for now, assume that there actually was nothing, at least in terms of the something that we know from our known Universe (which means “all” in Latin).
Whatever there was before, was not part of our Universe, because if it was, then it would technically not have been “before”. And if it’s not part of our Universe, then space and time would not exist as we know it, since spacetime is an internal attribute of the Universe itself. Therefore it makes sense to say there was “nothing” in term of our physical reality.
“It is easier to believe that there was nothing before there was something than that there was something before there was nothing.” ― Julian Huxley
How does physics then explain a Universe from nothing? Isn’t this against some physical law of conservation of energy? How can everything come from nothing?
Quantum foam — temporary fluctuations
The same thing actually happens all the time all around us. Something pops into existence out of nothing all the time — and disappears again.
Even though the definition of vacuum is “empty space”, most empty space is in fact not entirely empty. Even in the purest vacuum far away in some interstellar medium in space, the vacuum is bubbling with virtual particles and energy (which are two sides of the same thing, as Einstein taught us with E=mc²). Particle and antiparticle pairs pop into existence for a short amount of time and annihilate each other again, releasing photons in the form of gamma-rays (high energy photons). How can that something come out of nothing?
Easy peasy: The pair just borrows a little energy and give it back when they disappear.
Just like accountant balancing sheets, the overall energy needs to be conserved. That’s what the conservation of energy law is about. But small fluctuations can happen if we look at smaller quanta. A particle is the smallest quanta possible of a specific field. For example, a photon is the smallest quanta of the electromagnetic field, an electron is the smallest quanta of an electron field, etc.
The thing is, that everything in our universe on a subatomic level is actually all just statistical probabilities of fields. The smaller period of time we consider, the larger the possible fluctuation of energy is possible.
Matter and energy can fluctuate even though it’s overall in a stable equilibrium of nothing. Just like looking at a distance at the surface of the ocean, where it seems calm and smooth, it seems like the vacuum is a stable nothing when observing it at our macroscopic level. It’s not until you zoom in closer to the surface, that you notice the waves and turbulence in the ocean and the fluctuations of something in the empty space.
For an ultrashort period of time, it’s possible that there are small fluctuations of energy — small enough for a small particle pair to borrow some energy and quickly give it back again by annihilating each other. Since electrons are some of the smallest particles and hence requiring the least energy to exist, the most observed particle- and antiparticle-pairs is the electron and the positron (a positive version of the electron and the antiparticle of the electron).
The shorter the time period we consider, the higher the uncertainty and hence the higher the possible fluctuation of energy is possible.
Could the Big Bang have been just a temporary quantum fluctuation on an extremely huge scale (from our point of view), creating our Universe, which after a few gazillions of years will give energy back to where it came from?
We are nothing
Another thing to consider is the total energy of the universe. We are — in fact — nothing: All the energy in the universe adds up to zero.
There are two kinds of energy:
- Potential energy, which depends on the distances from an object with a mass and hence the position in a gravitational field and
- Kinetic energy, which is the internal energy of a moving or vibrating object
The potential energy is negative when it’s close to high mass and goes to zero when we go infinitely far away. This is because we have to add energy to move away from a gravitational field. So the closer objects are together, the more negative the total potential energy.
The internal kinetic energy is zero when an object is still and by adding energy it will move. The faster an object is moving or vibrating, the higher the kinetic energy it has.
The conservation of energy says that the total energy has to be conserved, but the energy can transform from one form to another. This is what happens when an object falls in the gravitational field on Earth. If it starts from a point away from the ground, it has potential energy corresponding the hight from the ground. When it falls, the potential energy gets transformed into kinetic energy, while the total energy must stay the same. When it hits the ground, it’s energy gets transferred to whichever object it has hit.
When we look at the total energy of the Universe, it might surprise that the total energy of the whole world is actually zero. At the beginning of time and space, where the whole universe was theoretically one single point, the potential energy was infinite negative and the kinetic energy was likewise infinite positive which also made it extremely hot (1 billion K).
While the space expanded and distances between particles, and later more massive objects, grew, the potential energy also became less negative while the kinetic energy became smaller and the universe cooled.
The total energy stays the same: it all amounts to a big fat zero.
From what we know now, it seems like we live in an open universe, which means that it will just keep expanding, and hence both the potential and the kinetic energy continues to zero. It will be like hell freezes over, also called “The big chill”.
Another option could be that the Universe stops expanding at some point, and starts contracting again. This would result in the total potential energy going to more negative values and the kinetic energy becoming larger again, back to the starting point and given that human beings still exist in some form, we’ll all burn like in hell. This possibility is called “The big crunch”.
Hard to be completely positive about our future in the Universe, but on the other hand, we’ll still have some imaginary gazillions of years to go. Better not set the time machine with too many zeroes into the future by mistake!
We might be nothing but a temporary fluctuation.
Science has more questions than answers and every new discovery or deeper knowledge just opens up to new questions. Our Universe is full of wonder which makes it and the science of it truly wonderful!