Action & Reaction: Equal Opposites

[soothsayer]

In my opinion motion is related to big bang as follows:

1. Big bang happened, space expanded. This is motion.

But in the comoving sense, the Big Bang doesn't cause any motion. Motion is caused by the energy and the potential that existed in the universe at the time of the Big Bang expansion. Those distant galaxies aren't really moving away from us at a speed faster than light, it's just the space between us and them expanding.

As long as you understand that, that what you're saying here is basically right, but let's look more in depth at what happens...

Universe begins in a very hot, dense state. The Big Bang occurs at t = 0 and spreads out all this energy. Conditions in the early universe allow for creation of quarks, neutrons and protons, and electrons. These combine to create Hydrogen, Helium, Deuterium, etc. We now have a giant cloud of H-He gas somewhere in the universe separated from everything else in the universe. But, we look at the center of momentum of the cloud, there is NO total momentum or kinetic energy here to begin with, just a lot of potential due to gravity. This potential pulls the gas together into a star which ignites and fused H and He into heavier elements like Carbon, which later is ejected when the star supernovas and disperses throughout the galaxy to infuse other clouds with the elements required for life. The process repeats, with terrestrial planets and life now being formed. Life on Earth evolves, I am born, I push a pencil on my desk.

This all began from a cloud of gas that has no kinetic energy in our frame of reference. The energy for creating life came from gravity, and the potential it created inside the gas cloud, not from the big bang, though all the matter did come from the big bang, that is, if you consider the big bang to be the creation of energy in the universe, and not just the mechanism for expansion of the universe. We really DONT know where the energy came from in the first place...

I'm still kind of confused as to what this has to do with your original question

 

[PeterDonis]

Universe begins in a very hot, dense state. The Big Bang occurs at t = 0 and spreads out all this energy.

No, you have this backwards. The Big Bang occurs at t = 0, and *then* the Universe is in a hot, dense state, with the hot, dense matter and energy expanding. But "expanding" must be interpreted carefully; there is no pre-existing space that it is expanding into, just as there was no pre-existing matter and energy before t = 0 that the Big Bang started expanding.

Actually, strictly speaking, saying that the Big Bang occurs at t = 0 isn't quite right either, because t = 0 is a singularity and isn't actually part of spacetime. The strictly correct statement is that the closer we get to t = 0, the smaller, hotter, and denser the Universe is. But that's often glossed over since it's a technical point that doesn't affect a lot of discussions.

This doesn't really affect the rest of what you said, but I think it's important to understand what the Big Bang model actually says.

 

[soothsayer]

No, you have this backwards. The Big Bang occurs at t = 0, and *then* the Universe is in a hot, dense state, with the hot, dense matter and energy expanding.

Ok, thanks for the clarification. Kinda feels like a chicken and the egg scenario to me.

But "expanding" must be interpreted carefully; there is no pre-existing space that it is expanding into, just as there was no pre-existing matter and energy before t = 0 that the Big Bang started expanding.

This I was well aware of. I hope I wasn't suggesting otherwise.

 

[Dale]

In my opinion motion is related to big bang as follows

If you accept the big bang model then the statement "X is related to the big bang" is a tautology, regardless of X. It is true, but not very informative.

 

[nitsuj]

Actually, strictly speaking, saying that the Big Bang occurs at t = 0 isn't quite right either, because t = 0 is a singularity and isn't actually part of spacetime. The strictly correct statement is that the closer we get to t = 0, the smaller, hotter, and denser the Universe is. But that's often glossed over since it's a technical point that doesn't affect a lot of discussions.

lol I cracked up reading that. Perhaps it doesn't effect allot of discussions because they are made in the context of the theory's limits. That said without the physical universe, what's there to discus

 

[Naveen3456]

. We now have a giant cloud of H-He gas somewhere in the universe separated from everything else in the universe. But, we look at the center of momentum of the cloud, there is NO total momentum or kinetic energy here to begin with, just a lot of potential due to gravity. This potential pulls the gas together into a star which ignites and fused H and He into heavier elements like Carbon, which later is ejected when the star supernovas and disperses throughout the galaxy to infuse other clouds with the elements required for life. The process repeats, with terrestrial planets and life now being formed. Life on Earth evolves, I am born, I push a pencil on my desk.

This all began from a cloud of gas that has no kinetic energy in our frame of reference. The energy for creating life came from gravity, and the potential it created inside the gas cloud, not from the big bang,

Why don't you think is like this:

Gravity is the result of big bang. Gravity causes potential which pulls the gas together (causes it to move, and the story continues).

So, what's the problem, if I say big bang caused the gas to come together?

 

[Naveen3456]

As regards the question of 'action and reaction' between matter and space, I think that 'space' can also in some vague way be considered to have the properties of matter.

I say this because scientists say that fluctuations of space lead to the production of 'material particles'.

 

[nitsuj]

I would think there is discontinuity between SR/GR and the statement "fluctuations of space lead to the production of 'material particles'." SR/GR is kinematics/geometry. comparatively, "material particles" from nothing is "magic".

 

[Nugatory]

I say this because scientists say that fluctuations of space lead to the production of 'material particles'.

Not really. Some pop-sci sources say things that could make you think that, but they're over-simplifying to such an extent that they're misleading if not outright wrong.

 

[BruceW]

I'm guessing that 'fluctuations of space lead to production of material particles' is meant to be talking about fluctuations of a quantum field. This is not related to the curvature of space, or anything related to general relativity (as far as I'm aware). The reason they say 'space' is because they are talking about the vacuum fluctuation.

 

[soothsayer]

Why don't you think is like this:

Gravity is the result of big bang. Gravity causes potential which pulls the gas together (causes it to move, and the story continues).

So, what's the problem, if I say big bang caused the gas to come together?

Well, you could, but as DaleSpam already said, it's a tautology. It's a redundant statement that doesn't really tell you anything. For example, at the beginning of my life, I was brought into this world by my mother, and now I am sitting here pushing buttons on a computer keyboard. You COULD say that it is because of my mother that these buttons on the keyboard are being pressed, but that tells you nothing about the process by which these buttons are actually being pressed.

If it were enough to say "this is caused by the Big Bang", then consider physics solved!

In other words, what point are you trying to make by invoking the Big Bang?