How do you explain "before the big bang"

[mr friendly guy]

I remember reading about Lawrence Krauss about how something can come from nothing and how the universe could come into existence simply because the laws of quantum mechanics allow it. This would of course mean that the laws predated the universe. Yes I am aware that scientific laws are merely descriptions unlike human derived laws which are enforced. So the laws Krauss talks about would be a description of how the "pre-universe" behaved. Also note string theorists also talk about the before the universe and various hypothesis on how the universe could form from pre existing structures.

Now the other problem is, the term "before the big bang" is nonsensical if we take the usual chronology point of view, since time came into existence at the moment the universe did, so a time before the big bang is nonsensical in that sense. Now I think I understand what Krauss and others mean when they talk about before the universe but I am trying to explain it to myself in analogies, which I hope will translate well for the lay person. I like some criticism of my attempt.

Basically if we take the universe as analogous to a person. In this sense, time before the big bang, would be like celebrating your birthday before you were born. In this sense, time (for our universe) is analogous to the life story of the person. Thus to talk about events involving yourself occurring before you were born would be nonsensical (no time travelling allowed. ). Continuing on the person analogy to one universe theme, there is an older person. Events could very well involve this person before you were born. Time (for that universe) would be analogous to the life story of that older person. So in this sense events could occur in this older universe "before" our universe was born.

So "before" the big bang could be a nonsensical term depending on what you mean. Using my analogies, if you mean like describing an event which you are involved in before you are born, its nonsensical. However if you mean describing an event which occurred to someone else (another universe or the "pre-universe" state) then that could make sense.

Thoughts from our physics buffs here?

[Steel]

Current theories have a period known as 'inflation' which precedes the standard hot Big Bang. This is driven by a field known as the inflaton which sort of wobbled for a bit before settling down. The motivation for inflation is that otherwise the universe would be too lumpy, and inflation makes it smoother. Inflation is a period of exponential growth of space time so oddly you kind of asymptotically approach time = 0 as you go back, never reaching.inflation only had to last for 30 e foldings though, so there was time before, during which I don't recall what was supposed to be happening.

[His Divine Shadow]

The motivation for inflation is that otherwise the universe would be too lumpy, and inflation makes it smoother.

I thought it was the other way around.

[Borgholio]

It is. First the Big Bang, then things settled down a bit and space expanded, then (for some reason) space accelerated so that it expanded faster than lightspeed. After awhile it slowed down to what it is now, but is once again accelerating.

[General Zod]

Have a gander at this article. It's a good starting point but it's not really the sort of topic you can compact into neat sound-bites. But tl;dr there isn't really any "before" the big bang, and our perception of time isn't a very good basis as a model.

http://www.nature.com/news/theoretical- ... me-1.13613

[cadbrowser]

It is. First the Big Bang, then things settled down a bit and space expanded, then (for some reason) space accelerated so that it expanded faster than lightspeed. After awhile it slowed down to what it is now, but is once again accelerating.

I was under the impression that the expansion slowed down to what it is now and is continuing, but I don't recall that it accelerated again. And indeed the volume of expansion is WAY faster than lightspeed theorized to be something like 1078 (conversely 1026+ linearly) in a timespan between 10-36 - 10-32 seconds after the big bang.

So "before" the big bang could be a nonsensical term depending on what you mean. Using my analogies, if you mean like describing an event which you are involved in before you are born, its nonsensical. However if you mean describing an event which occurred to someone else (another universe or the "pre-universe" state) then that could make sense.

For me, from a laymen's perspective, I think this is a pretty darn good analogy. I mean, it doesn't really answer the question of what the universe was like before the Big Bang; it does well to explain how asking that question doesn't make sense in light of the issue with time (as it is understood from a cosmological perspective) not existing either.

[Borgholio]

I was under the impression that the expansion slowed down to what it is now and is continuing, but I don't recall that it accelerated again.

http://en.wikipedia.org/wiki/Inflationary_epoch

Basically it expanded extremely rapidly, then slowed after matter began to form. Since then it has been expanding slowly until this point where the force of gravity is no longer enough to slow the expansion.

[cadbrowser]

I was reading that while I was posting. I am still confused as to where it states that the universe is accelerating again tho. What am I missing?

Shit, nevermind...I found it. Here

Apparently, according to the LambdaCDM model dark energy is the culprit behind the accelerated expansion of the universe.

[Borgholio]

Yeah, trouble is that we don't know what the fuck Dark Energy is, where it came from, how it works, or anything about it. Yet, it seems to be dooming the entire goddamn universe. Wonderful stuff, it is.

[cadbrowser]

Yeah, I've often wondered what it, and Dark Matter, itself is as well, as a concept to grasp as easily as energy and matter. The only thing my limited brain can surmise is that it is just energy/matter that absorb all of currently detectable ranges of the Electromagnetic Spectrum. Since, theoretically, the limit for the long and short wavelengths are the universe and Plank length respectively, I would guess that any "excited" states may emit along those wavelengths we don't yet have instruments to "see" just yet.

My limited understanding though doesn't do much for extrapolating further from that premise into what that even actually means. Probably I'm just talking out of my ass though anyway. Wonderfull stuff, indeed.

[Borgholio]

Well Dark Matter is easier to comprehend...it's just matter that is invisible. Ordinary hydrogen gas and dust can be dark matter if it's in the middle of a void where we can't see it. Black holes, dead pulsars, etc..

[cadbrowser]

Ah, I guess that is what I was trying to allude to. So then, if that is all what dark matter is, then why wouldn't dark energy be energy that is "invisible"?

[Borgholio]

Ah, I guess that is what I was trying to allude to. So then, if that is all what dark matter is, then why wouldn't dark energy be energy that is "invisible"?

Because dark energy cannot be observed. Neither optical nor radio telescopes can detect it and it emits no radiation. The only clue to it's existence is the force it exerts on space-time itself.

Dark matter is simpler to quantify because it just needs to be illuminated, heated, or silhouetted by a passing start, galaxy, or black hole to become visible.

[Atlan]

Ah, I guess that is what I was trying to allude to. So then, if that is all what dark matter is, then why wouldn't dark energy be energy that is "invisible"?

Because dark energy cannot be observed. Neither optical nor radio telescopes can detect it and it emits no radiation. The only clue to it's existence is the force it exerts on space-time itself.

Dark matter is simpler to quantify because it just needs to be illuminated, heated, or silhouetted by a passing start, galaxy, or black hole to become visible.

Dark Matter is NOT that easy to quantify. There's supposed to be so much of it that if it were just unilluminated "regular" or baryonic matter, we wouldn't actually be seeing the rest of the universe, because it would get in the way. In fact our only indication that there is something out there is that we see something interacting with the rest of the universe via gravitational means. That, in fact, seems to be pretty much the ONLY way it interacts with "our" kind of matter.

IOW, we don't have a fucking clue as to what actually compromises Dark Matter, we just know that it's here.

[Steel]

Indeed dark matter doesn't seem to interact terribly strongly with itself either. There are two galaxies colliding where the normal matter of the two galaxies is colliding, but the dark matter component has just shot straight through both the normal and dark matter of the other galaxy. You can see where it went only by the gravitational effects of its presence. This is one of the principle pieces of evidence for dark matter existing, as you need dark matter to make any sense out of this collision.

[cadbrowser]

Ah, I guess that is what I was trying to allude to. So then, if that is all what dark matter is, then why wouldn't dark energy be energy that is "invisible"?

Because dark energy cannot be observed. Neither optical nor radio telescopes can detect it and it emits no radiation. The only clue to it's existence is the force it exerts on space-time itself.

Dark matter is simpler to quantify because it just needs to be illuminated, heated, or silhouetted by a passing start, galaxy, or black hole to become visible.

Dark Matter is NOT that easy to quantify. There's supposed to be so much of it that if it were just unilluminated "regular" or baryonic matter, we wouldn't actually be seeing the rest of the universe, because it would get in the way. In fact our only indication that there is something out there is that we see something interacting with the rest of the universe via gravitational means. That, in fact, seems to be pretty much the ONLY way it interacts with "our" kind of matter.

IOW, we don't have a fucking clue as to what actually compromises Dark Matter, we just know that it's here.

Wow, I can't wait until they find out more information on these wierd concepts. It really messes with the mind.

[Borgholio]

It really messes with the mind.

Homer: What is mind? No matter. What is matter? Never mind.