Pre Big Bang

Are we sure that we will not be able to explain the events that took place pre big bang? The notion of “event” as we understand it, in our own space time framework, may break down; but we may still be able to postulate something in those alternate dimensions, wont we?

Yes, some theories do extend before the Big Bang. For example, the ones that hold that this universe budded off of an older one; or that our universe came into existence inside a larger preexisting domain.

…but when Hawkins claims that the events before big bang have had no impact on what happened after big bang, he is obviously suggesting that the causal chains breaks down there. so the scientific method of inferencing does not actually apply in postulating what there was pre big bang.

That is interesting.
I thought that timespace started at the Big Bang.
How could there be something ‘before’ time?


And we don’t know, yet, that “the causal chains breaks down there”.

Our time & space started at the Big Bang.

sorry … i meant stephane hawking …
in discovery channel’s 2010 release, Stephen Hawking’s Universe … as reference
… and yes, there can’t be anything before time … however unobvious this is … however, why is it so that some scientists are trying to come up with theories as mentioned which date before time (i.e. before big bang)?

Never underestimate a scientist’s ego. To be the one who comes up with a solid model that accurately describes things that Hawking said cannot be described is a surefire way to hit the geek lottery.

Also, such a concept would probably get pretty close to the Grand Unified Theory, and then that scientist would be up there with Einstein.

The answer is that we are not sure. We don’t even know for sure whether there was a “big bang” at all… all we know is that at some point in the past the density of the universe was much higher and the entropy much lower.

What happened before the Big Bang is too fascinating not to speculate on. As long as scientists make it very clear that it’s all speculation and based on plausible extrapolations of what we currently know then it’s a fantastic game that could lead to great results even if the particulars aren’t true.

But the particulars count a lot. Some people dispute that a Big Bang even occurred, and the definitions of what the Big Bang was or inflation was or what whatever happened was differ, overlap, or outright contradict each other.

We’re not sure about anything earlier than the appearance of the microwave radiation that the WMAP Probe found. Scientists certainly use that to reason backward. But the farther back they go the more uncertainly in their reasoning.

Will we ever know? Over time there’s bound to be consensus on things that are openly disputed today. But not tomorrow.

In ‘vanillas’ big bang theory (i.e. simply applying Einstein’s general relativtiy to cosmology) it doesn’t make sense to talk about before the big bang as it signifies an event (well, not even an event really) at whcih all maximally extended worldines ‘start’. I believe you can maximally extend the FLRW solution beyond the bang, but this relies on the 100% isotropy and homogenity of the solution, whereas it’s trivial to observe that the univesre deviates slightly from this.

What if in the far distant future, some post-corporeal consciousness does indeed find the answer. . .

For that matter, we don’t even know for sure that there was a last Thursday.

Nonsense. I’ll show you my posts. :stuck_out_tongue:

No, don’t show me your posts, show me your pres.

This sounds like a question of whether or not there is bottom turtle.

I don’t keep up with the current state of this field. Has the idea that the timeline from the Big Bang to now is just a subset of a series of expansions and contractions of the universe been discredited?

There are hypotheses that universes do evolve from Big Bangs to Big Crunches back to Big Bangs again, but I think they count as technically separate universes since you can’t regain any information from a previous incarnation. If that’s what you’re referring to then I’m pretty sure that recent observations of an increasingly speedy expansion of the universe has eliminated those from serious consideration.

Well, not entirely. We know little enough about the mechanism behind the dark energy (or whatever the heck it is) that we can’t rule out the possibility that it might someday turn off or even reverse, in which case a crunch could still be an option.

The problem is that with the current mathematical models the density of the universe becomes infinite and space-time becomes infinitely curved at a certain point. The current models can’t work out what happens “through” the infinities.

It doesn’t mean that there was nothing there before, nor that “ ‘Before the Big Bang’ doesn’t mean anything.”, it just means the current models can’t provide a sensible answer because the infinity point of the singularity causes the equations to break down.

What’s the actual evidence that there was a singularity?

I know the universe is expanding, and background radiation and all, but can’t we only “peer back” to a few hundred thousand years after the big bang? Couldn’t there have been some other beginning than a point of infinite density?

I recall an idea floating around the pop science magazines a few years ago about “branes”. Supposedly two multidimensional branes could have collided, causing our universe to start expanding from some initial finite density. What’s the state of this theory, and what evidence constrains other theories of this type?