Some questions about the big bang

Re: Some questions about the big bang


The center of the Big Bang is everywhere; it's right between your eyes. If you ran time backwards and stared at the tip of your nose the whole time, you would see everything fall into a point right at the tip of your nose.

The same thing is true in reverse, which is why everything appears to be moving away from us, no matter which direction we look.

Thank you, I've now read a bit more. But I'm still a little confused. I understand the red shift and distance of galaxies can be can be used to caculate the age of the universe, but the nature of the bang is still confusing me.

Surely not everything would come to the tip of my nose if time was run backward, it would just appear as if it is. Hmmm, that's still thinking of the big bang as an explosion from a point, but I'll leave here just because well, I don't know, it may give you an insight in to my confustion.

If the explosion was every where that what is causing the expansion? If the explosion came from a point then the initial force would push everything away, but if the explosion was everywhere then why is anything moving? If the explosion was everywhere the wouldn't the force on the object be the same in all direction therefore keeping everything still? If the movement was created by the energy produced from the matter and anti matter then why is everything uniformly expanding, would things not be moving towards as well as away from us?


Also is there any good websites bout this, most of the ones I've found are all fairly similar.


Thanks

Re: Some questions about the big bang
[/quote]

The center of the Big Bang is everywhere; it's right between your eyes. If you ran time backwards and stared at the tip of your nose the whole time, you would see everything fall into a point right at the tip of your nose.

The same thing is true in reverse, which is why everything appears to be moving away from us, no matter which direction we look.[/quote]

Wow - thanks. I'm just a plain old lay person who is facinated by it all.

so - are you saying that if I were a person or object standing where I am, the universe would be expanding from my viewpoint of right between the eyes, the same way that a person or object that is standing 1,000 light years away is seeing it expanding from the viewpoint of right between the eyes, as well as a third persons, etc?

wouldn't there be infinite overlap if it were expanding from every single point? Like if every single point in the universe is the center of it all?

If you answer this one, I have another, but it hinges of the above....

Thanks so much.

Re: Some questions about the big bang


Yes.



No.

The Universe is not expanding "into" any existing space. It is space itself which is expanding. Every point (in our three dimensional world) is the center of expansion: Literally.

So it's the space between the planets thats expanding, rather than them moving.

That's whymore distant planets have a greater red shift because theres more space us and them than there is between us and nearer planets.

Is that right?

Re: Some questions about the big bang


obviously that makes my brain hurt
Can you give an analogy of that?
I'm trying to visualize how everything can be the center.

When I read that space is expanding at x miles per hour, I would wonder why different galaxies and so forth didn't quickly become too far away for use to see.

But, if everything is expanding, then we are moving away to, so does that mean the distance between us and any other given point remains constant?
If that IS the case, then as terryg suggests, isn't that like remaining still?

Rosborne979 - you have no idea how exciting it is to ask a question like this, and actually get answers!
I really want to understand, but since I don't have the mathematics background, I don't now that I can......however, having some inkling of it is gratifying.

Yes. Well said.

Re: Some questions about the big bang


Hi Chi,

I'm glad to be able to help. I found this stuff very interesting back when I learned it as well.

Here's an analogy: Picture a giant loaf of raisin bread which is baking and expanding. Now imagine that you are one of the little raisins in the giant loaf, looking at all the other raisins moving away from you. No matter which raisin you pick, all others will appear to move away from you as though you were the center. And in a loaf without edges, you might as well be the center.

Re: Some questions about the big bang


My math skills are pitiful, but I still understand much of cosmology and relativity. You don't need math to understand many of the concepts.

Okay I am going to throw a spanner in the works now!

Scientists don't know if the Universe is infinite in size or age at present. Age appears to be 13.8 +/- 0.1 billion years based on dating celephoid variables in remote galactic clusters and a very elementary interpretation of our big bang model. Diammeter maybe strangely be 40 billion light years, 200 billion light years or infinite when we consider exotic topologies or casual disconnects (see below) ... ugh!!!

Why? Well two reasons, firstly - we observe using electromagnetic radiation - which is limited by light speed across all relativistic frames of reference. Galactic seperation and the expansion of spacetime itself isn't limited to lightspeed under general relativity (a much misundertood exception to GR). The universe itself can be getting bigger much, much faster than lightspeed. Scientists suspect, but don't know, if its finite in size.. Our understanding is limited by how far we can see and how well we can understand very early stage big bang physics. We don't really even know how much of the entire universe we may observe.

Secondly and here's the kicker, the Big Bang only works if you accept inflation occured in the first 10 ^ -34 of a second. If you divided 1 second by the presumed age of the universe in seconds, and then did it again you get an idea of the time scales here. In this period the Universe expanded from a singularity to the size of a large apple. As it did this its rate of initial expansion was ultra fast (10 ^ 30 times lightspeed). Inflationary expansion stopped as the universe cooled and relativity kicked in. So what you ask? Well causality that's what. We see and observe using light. The Universe unfolded initially extremely faster than lightspeed with nothing impeding this event. Not even gravity can propogate at this speed (its a lightspeed limited force too). So fragmented parts of the Universe (really all super hot energy - no matter) trapped within expanding spacetime itself, unfolded way, way faster than light can travel. These parts became over time Hubblespheres - and each appears disconnected - even by gravity, from the other. We have no idea how many Hubbles Spheres were created because we don't understand the upper energy limits of what causes a big bang.

Today we may not being seeing our Universe, we might be only observing areas within our Hubblesphere. A Hubble Sphere is a sphere that is defined by how far light can travel since the period after the big bang when spacetime became transparent - so light that is around 13.5 billion years old or younger. And inflation means the Universe can be far, far larger than our Hubble Sphere and we'd never know.

Suddenly our Universe under inflation means it could be comprised of trillions and trillions of Hubble Spheres - potentially each with their own slightly different laws of physics (dependent on starting energy and other factors) - all too far apart to see each other. Our Hubble Sphere has the physical constants required to support intelligent life - others might not. Our Hubble sphere exists in a spacetime that is inflating at an increasing rate (other might not).

Imagine a grenade exploding - where each piece of shrapnel is a Hubble Sphere wherein certain laws of physics hold. We live in one piece of shrapnel that can itself expand faster than relativity. But the universe itself can be potentially enormous number of hubble sphere.

GR holds to close galactic scales, it does not limit the expansion of dimensional space time itself. Who knows what laws hold in other Hubble Spheres or between Hubble Spheres?

We don't see much of the universe under current leading theories resulting from a deeper understanding of the Big Bang. We observe only our Hubble Sphere within it - and that could be a very, very, very small component of the entire Universe. We don't know what all the other Hubble Spheres, and space time itself, is doing!

I would say thats less of a spanner and more a whole tool box, maybe even a small hardware store...

I'm going to have to re-read it all at a time when I have more time, but my initial reaction is that if space can expand faster than the speed of light the we can never work out if it's finite, because if something is moving away from us faster than the speed of light we'd never be able to see it or reach it.

We could if we could devise a tool that would sense phenomena traveling faster than the speed of light. Remember all tools do is expand and enhance our sense and capabilities. This is all speculation, at least at the moment, as we have no idea what something travelling faster than the speed of light would look like and therefore how to detect it.