Mathematically, is there any difference between a colossal inner force pushing out the singularity and continuing to expansion, and a colossal outside gravity pulling out the singularity and continuing to expansion (though slowed for a while by actual gravity between matter)?
Asked
Active
Viewed 589 times
-1
-
2If you imagine the "outside gravity" as caused by a massive 3D sphere around the universe or around the primordial singularity, then such "outside gravity" would be zero. It is similar to the electric field being zero inside an evenly charged sphere. The pulls from different sides cancel each other as long as the inverse square law applies. – safesphere Sep 26 '17 at 16:06
-
4The Big Bang didn't happen at a point! – John Rennie Sep 26 '17 at 16:08
-
Outside the universe? The universe was the singularity. Not sure universal expansion is caused by force? It is the creation of new space, not the pushing about of matter. – JMLCarter Sep 26 '17 at 16:19
-
@JohnRennie: It did according to Lemaitre (L in FLRW). Your viewpoint is not sustainable. You are taking the theory assumptions beyond the limits of applicability of the theory. So you get nonphysical singular results of the infinite mass and distance. In addition, your solution is unstable, because you "infinite universe" based on the flat space collapses into a point if space is not flat by any infinitely small amount. If anything, the "infinite universe" result simply proves the FLRW model incorrect rather than the model dictating the universe to be nonphysically infinite. – safesphere Sep 26 '17 at 16:19
2 Answers
3
Your question falls into the common trap of thinking that the universe started out as a infinitesimal point that expanded, and for the record we should make clear that:
But leaving this aside you've asked an interesting question, but I'm afraid it has no answer.
If you saw a stone in the air you'd know someone must have thrown it because stones just don't hang around in mid air. And, unless you just happened to see the stone at the apex of its trajectory, you'd expect the stone to be either going up or going down.
Likewise the universe can't just be sitting still. It must be either expanding or contracting, and observation shows that it is expanding. That means something must have thrown it i.e. something must have been responsible for its high initial expansion rate. The problem is that classical general relativity does not, and cannot, tell us what happened at the Big Bang because in GR the Big Bang is a singularity.
That's why I say there is no answer to your question since we simply don't know what happened at the Big Bang. We expect that quantum gravity effects become import as we work backwards in time towards the Big Bang, but right now we have no established theory of quantum gravity.
The nearest anyone has come to a theory of the Big Bang is Loop Quantum Cosmology, and that predicts that at the very, very high densities near the Big Bang gravity became repulsive. Before the Big Bang was a contracting universe and the repulsion at the Big Bang caused a bounce (wittily called the Big Bounce) that produced the expanding universe we see today. However we need to note that Loop Quantum Cosmology is highly speculative and far from a widely accepted theory.
John Rennie
- 355,118
-
According to Georges Lemaitre who is known as "L" in "FLRW" and the father of the Big Bang theory, the Big Bang did happen at a point that he called "the primeval atom" or "Cosmic Egg". You should stop promoting a nonphysical singular solution of mathematical equations taken beyond their limits of applicability and remember the words of Albert Einstein that "not all mathematics lead to correct theories". – safesphere Sep 26 '17 at 22:43
-
1@VictorStorm: my views reflect the mainstream views in physics. You and Lemaître are the ones who are out of step, and Lemaître has the excuse that he was writing 100 years ago and thought the universe was closed. – John Rennie Sep 27 '17 at 04:29
-
Fair enough :) Interestingly, after space was measured flat, the entire Wikipedia was carefully edited out to remove references to the initial size of the universe. One can hardly find either "a point" or "infinite". The dilemma is that "a point" contradicts the consensus theory conclusion while "infinite" is singular by mass and distance and therefore has no physical meaning. Either way FLRW is doomed, but no one has a courage to admit it. The Milne (Walker's teacher) model was ruled out, because it was singular. The clock is ticking for FLRW too. You should always choose physics over math :) – safesphere Sep 27 '17 at 04:49
-
OK, but mathematically, is there any difference between an object being pushed out and the same object being pulled out, say a balloon being inflated vs the same balloon being put in a vacuum that sucks it out like gravity? – user170159 Sep 28 '17 at 17:43
-1
Maybe the big bang is literarily reverse gravity... If it really is a kind of reverse gravitational push, this implies something we cant quite comprehend with our minds. Because general relativity proves that gravity is caused by heavy massive objects pulling and curving space time around it causing other objects to roll along it’s valley.
So an outward gravitational push would imply that maybe because of the huge energy blast of the big bang the object causing it would become in a negative energy state causing it, according to E=mc2, to have a negative mass and causing this object to make a kind of mountain in 2 dimensional space time setting our universe in motion rolling downwards this hill. And while rolling kind of unfolding in our current universe. And so explaining the accelerating expansion of our universe.
I’m actually saying something rather strange. But I think what i’m saying can be a possibility, I know it is a different view of the Big Bang and what it might have set in motion. Because from what I understand, the Big Bang was this small packet of enormous energy exploding and giving rise to our universe, and because of this enormous blast pushing everything in motion outward. But I am suggesting that the bang was so big that it caused spacetime around it to curve inside-out and in stead of attracting, repelling.
Daan Rijks
- 179