What prevents scientists from being able model what was before the Big Bang?
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Well at the big bang everything was just a dot so we really cant know if anything even existed back then
Our current physics theories have limits. Quantum phyiscs can describe things where gravity doesn’t matter. General relativity can describe things where quantum effects don’t matter. During the big bang both mattered, but we have no theory of everything that can combine them.
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The short and sweet answer is that the Big Bang introduced the concept of “time” itself. Asking what happened *before* would be like asking what’s north of the North Pole. The question doesn’t really make sense.
Let’s imagine a few things. Say you’re floating in space. I, an omnipotent being, said “screw it, I’m making all matter and energy in the universe except for you disappear.”
So now you’re floating around in nothing; no stars, no planets, no light, nothing. But not quite. There’s still something. There’s still the Space-Time fabric. Space and Time are physical objects in our universe. Even darkness itself is still something.
Before the big bang, that didn’t exist. There was literally no space or time. What’s there before Time itself? True nothingness. Some will say the universe was a point before the big bang but that’s not really the case. To say “before the big bang”, there needs to be Time before the Big Bang. But there was no Time, so there’s absolute nothingness. Humans and computers have a hard time grasping the concept of absolute nothingness.
It reminds me of something my computer science teacher once told me in CS1. You can compress data of any size down to a single bit. The problem is you cannot then decompress it. If all matter in the universe was an infinitely hot infinitely dense point, in theory no information remains for us to find afterward.
We do not even have a theory that explains how we might determine the answer to your question, assuming that time itself did not start with the big bang. However, this is based on our current understanding. It is always possible, perhaps even probable, that more study, technology, and theory will give us new ways of looking at the beginning of the universe.
The key to understanding this problem requires you to know about [Planck Units](https://en.wikipedia.org/wiki/Planck_units).
Planck time is the time it takes a photon to travel 1 Planck length and Planck length is the distance a photon travels in 1 Planck time.
Planck scale is where the physics equations that got you to this point break. It’s not just general relativity. This is the end of the line for quantum field theory too. All of the equations that do an incredibly amazing job at describing how systems evolve hit a hard stopping point.
Forget about modeling the universe at or before t=0, it can’t even be modeled for period of time after t=0. It’s not even clear if it makes any sense to talk about time within Planck time. At this point the definitions of distance and time no longer apply. In fact there would need to be a new way to define time and space in order to go further back.
The name for this period in big bang theory is the Planck Epoch. Calling it an epoch is funny. It lasted 1/10,000,000,000,000,000,000,000,000,000,000,000,000,000,000th of a second.
At this time, accepted physics has tied itself up in what hopefully is a Gordion knot. With no more physics, any attempt to go further requires stoners or philosophy undergraduates or apparently Nobel winning physicist [Roger Penrose](https://en.wikipedia.org/wiki/Conformal_cyclic_cosmology).
We used to think the universe oscillated between expansion and collapse.
Then we made some measurements of cosmic background radiation that seemed inconsistent with that theory, so we thought there was just the one big bang and the universe would keep expanding until all energy reached its lowest level in the heat death of the universe.
Recently there have been some revisions in string theory that again open the possibility that the universe follows an oscillatory model, in which case there could have been any number of big bang / big crunches before the one we know and love.
https://www.space.com/what-came-before-big-bang.html
The truth is we don’t know the answer and need more data.
Nothing. We can create models from various different perspectives. QM would posit a thermal equilibrium that had arbitrary perturbations – one of which ended up in this conversation. Rodger Penrose posits that energy tunnels back in time & creates a big bang.
There are plenty of models about what could have been before the Big Bang. However nothing to actually experiment against, nor any real apparent valuable reason to prove a given model. What would the scientists who proved this earn their Nobel prize in?
It’s a simple thing, a singularity.
A singularity is a mathematical object rather than a physical one. To put it simply, it’s a point where our math is undefined, or spiralling into infinity. The best example would be dividing by zero.
There are a few such singularities we encounter in our theories of physics. The most famous one is the singularity at the center of a black hole. Another would be trying to model the universe through the viewpoint of light itself.
And there’s the singularity at the heart of the big bang. Do not confuse it as the big bang itself though, because the big bang is the moment **immediately after the creation of the universe**. It happens roughly 10^(−43) seconds and on after time zero. But at time zero, we get infinite temperatures and infinite densities. And because whenever you add, or substract or do anything else with an infinity only gets you infinity again, we cannot do math with a singularity, hence we cannot describe what happens at time zero, or the center of a black hole.
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