The only thing we know for certain about either of your questions is that we absolutely won’t ever know the answer to either of your questions for the simple reason that due to the universe being completely opaque to light up to about 300,000 years following the Big Bang, we cannot possibly observe anything that happened prior to that. We can speculate and theorize, of course; the current thinking insofar as I’m aware is that the answer to both questions is: nothing. Nothing existed prior to the Big Bang, because that’s the moment when space and time began. And all the stuff we see around us may have popped out of the vacuum as a random, albeit spectacularly energetic, fluctuation in the so-called vacuum energy–a sea of virtual particle-antiparticle pairs thought to be constantly forming and annihilating everywhere in space. The more energy such a fluctuation has, the less likely it is to occur–and ones with the energy-equivalence of the observable universe are so astronomically unlikely we’d only expect them to happen one time in something like 1 x 10[sup]1000[/sup] (figure guestimated from dim memory; actual value may vary) times the current age of the universe. But, it only had to happen once.
I read (possibly in “A Brief History of Time” but this was long ago) that maybe we are the result of a massive black hole from another universe. So as tons of material from another universe compresses into a single point, it somehow jumps into our universe, and explodes.
So what is the current feeling of the scientific community toward the Big Bounce? Theoretically, the universe could annihilate itself and recreate itself an infinite number of times. Is this still a popular theory?
Some schools of thought (I have no idea if it’s a common notion or not, be gentle) is that since matter, energy et al were condensed into a single point (point being a somewhat useless term here), time was essentially condensed as well. To clarify: there IS no t=-1 because everything from the (presumably nonexistent) t=-infinity to t=infinity was rolled into the “entity” that was the big bang. “Time” as we know it is simply everything that was folded all tight and neatly essentially unfolding piecewise.
Not to hijack but I have a small related question though:
When we talk about the big bang are we talking about the creation of the whole universe or the observable universe? Because I heard that if the observable universe were the size of a quarter, the actual universe would be about the size of the Earth, which seems to me like it would have a lot of bearing on this question. If it’s the whole universe current views are correct, if it’s considered to be the observable universe and maybe a little more, then t=-1 is simply “another random celestial pocket is about to burst.” (I’d assume the former but I want to be sure here)
Reminds me of:
From what I’ve heard though the bounce is classified as “possible, but not likely given current observation.”
The Big Bang refers to the whole universe, and takes into account that what we call our Observable Universe is only a small part of it. One thing to get straight is that the Big Bang theory suffers a similar misconception with the theory of evolution, in that it refers to the evolution of the universe, not the “creation”. The Big Bang discusses in detail how the universe has been evolving throughout its lifetime, and goes as far back as about t=10[sup]-44[/sup] seconds. But what happened before that is still open to speculation and is separate from the Big Bang theory (because at that point physics as we know it doesn’t work anymore).
One theory is that our universe is among other bubble universes floating in an even bigger, uh, hyperuniverse. That just begs the question of where that hyperuniverse came from, but since we don’t know anything about it we can make up anything we want, including just saying it’s been around forever.
Well, to even really begin talking meaningfully about what happened during the ‘creation’ of the universe, we’d need a real Theory of Everything; otherwise, as was mentioned above, we can’t really go back further than about a Planck time after the deed was done, since we’d have to account for quantum-gravitational effects.
However, we can speculate – one view is to assume that the beginning singularity is, essentially, a coordinate singularity, meaning that asking ‘what was before the Big Bang?’ would be similar to asking ‘what’s north of the North Pole?’.
Another view is to basically ‘exclude’ the singularity from the universe – for instance, if John Cramer’s transactional interpretation of quantum mechanics (which describes quantum interactions as a standing wave created by interfering retarded and advanced – backward- and forward-in-time – waves) is correct, the whole universe might just be a standing wave, not unlike a resonance on a guitar string (though a heck of a lot more complicated). Other such models include either large- or small-scale circular time, or time ‘forming’ out of space (by a fast, but not instant process, so time has a beginning, but there’s no ‘first moment’).
Stephen Hawking, I believe, recently proposed a model in which the ‘before’ is answered through a universe with (relative to ours) an inverse arrow of time, where time, so to speak, flows in the ‘other’ direction, and thus the ‘before’ of each universe is the ‘after’ of another (I distinctly remember reading an article about this, meaning to check it out further, but right now I can’t seem to find anything on it – I hope I didn’t just dream this).
That is the (very low but non-zero) probability that a male nerd will spontaneously be ask out on a date by a female. If the male exerts great effort in arousing the interest of every female in the observable universe, he can bring it up by about a factor 10…aka the Decanerd.
There are certain philosophical questions associated with existence itself (ontology).
What makes existence itself possible?
Why does this reality exist instead of any other?
When people ask what caused the Big Bang, I think it’s often because what they’re really looking for is an answer to these philosophical questions.
Well, we of course don’t have answers to these questions.
And I think it’s worth pointing out that the various hypotheses regarding the “origin” of the Big Bang: colliding branes, multiverse, cyclical universe, the universe “just is” etc, fascinating though they are, are not theories of existence, and can’t answer the forementioned questions.
I guess I just don’t buy that there was no “time” before the big bang. If a quantum fluctuation of vacuum energy created the big bang, then just before that was a period of no energetic interactions.
It may be moot to talk about since whatever was there before the bang was obliterated by the bang, shaking the cosmic etch-a-sketch so to speak but there was moment before the interaction.
I’m trying to keep religion out of it but claiming that there was no moment before the big bang sounds like dogma and not science. It’s uncomfortable to think about so we hand-wave around it and mark it “here be dragons”.
If we came from a squirt from another universe, where did it come from. If we’re in a cyclical expand-compress cycle, then there still had to be a beginning.
I’m trying to get the current, non-theological answer to “where did all this shit come from?”
Personally I have an answer that works from my POV. I’m trying to understand the other answer.
So you think time never started? But the idea of an infinity of past time has philosophical problems of its own. The most obvious being, an infinity of past time could never come to an end (that’s what “infinite” means, after all) and thus we could never get to the present.
Only if you do not accept the concept of an infinite universe. My personal belief is that if the universe is infinite in any dimension, it can (or must) be infinite in all dimensions. There was no “first” expansion; the infinite universe has always been expanding and contracting.
Time as we know it is one component of four-dimensional space-time. There’s no separation of them. You can’t take out height from the real world and you can’t take out time from the real world. (You can do so mathematically, but not physically.)
That’s why being unable to speak of time as something that exists before space appeared is a necessary consequence of our current understanding of physics. You either have space-time or you don’t. You can’t have one without the other.
That’s part of Einstein’s huge revolution. In the Newtonian world, which is what you are thinking in, time and space can be separated. In the Einsteinian world they can’t.
This has several consequences. It means that the equations that work for relativistic space-time break down at zero time. As said above, the Big Bang only kicks at a finite, if incredibly small, time after the instant of creation. That’s why there are so many speculations about the zero point. They can be fit into various mathematical representations that might become a more all-encompassing theory of everything, but right now they are incompatible with Einstein’s equations.
It also means that there is no good theory of time outside of and apart from space-time. Many physicists (and philosophers and crackpots) have tried to explain time in a myriad of ways but there is no general agreement on any alternative explanation.
You’re trying to stuff the universe into that box called “common sense.” That’s the box that once said the earth was obviously flat, and the sun obviously circles the earth, and light obviously is instantaneous and particles and waves are obviously two distinct things. One thing we’re absolutely sure of is that “common sense” doesn’t work when applied to the universe. “Common sense” is a matter of our limitations, not the universe’s. To understand the universe you have to give up “common sense” and follow the physics wherever it leads.
One place it leads is that we cannot speak meaningfully in any way of t = -1. It’s not dogma any more than the earth revolves around the sun is dogma. People may have considered that to be dogma at one time but they’ve had to let it go centuries ago. That time has a zero start is something that also been known for more than a century. Once you understand why that’s so, all the other wonders of modern physics become easier to grasp.
The same reasoning applies to the integers. Postulate an infinite number line. At any point x (say, zero), there are an infinite number of integers less than it. But an infinite number of integers cannot come to an end. Thus, a direct contradiction.
Only there isn’t any contradiction, this is a well-known “feature” of infinity. A lot of normal reasoning doesn’t apply.
False analogy. Numbers don’t pass as time does. Any time X (let’s say midnight on Dec. 31, 2000 for the sake of argument) was once in the future, then for an instant it was the present and it is now in the past. Numbers have nothing analogous to the “present”, “past” or “future” - they are just greater or lesser than other numbers.
This is applying infinity to math. It doesn’t work when applying infinity to the physical world.
There can be no transition from finite to infinite in the physical world. That means the creation of any infinite universe has to go directly from zero to infinite without ever passing through a finite state.
Some physicists do postulate the possibility of this; others reject any infinite universe except for one that has always existed because of the physical impossibility.
No known physical reality is infinite. (Some can be treated that way mathematically, but the infinities always have to cancel out in the final equations.)
People freely through concepts like an infinite universe around, but they become difficult to pin down when examined. The math analogy doesn’t work when applied to matter.
If it turns out that the universe is truly infinite, then I’m the one who has to undergo a shift in my thinking. So I appreciate the difficulty.