DLHill said:
After reading a few chapters of an astrophysics/ cosmology book, I took some time to think about the big bang and what existed before it. After thinking, I thought, "What if the big bang wasn't the beginning of existence? What if it were a just a big event that happened over the course of the existence?" Eventually, I came up with a hypothesis that maybe, the big bang was caused by a sort of hypernova? Before the big bang, there may have been a supermassive object like a star or black hole. An object millions of times larger than any we know of. What if this object were to collapse into itself under its own gravity and create a neutron star. The excess gases and debris would be flung out into space and eventually form small nebulae then stars and eventually, the debris from the supernovae would form planets and so on, which would get us to the present. I am sure this sounds completely ridiculous, but I am not an expert on cosmology (I am only 17), but if anyone has any opinions on this, please let me know. Thank you
It has become a common focus of research by professional cosmologists to work on "nonsingular cosmology" models where there is time and existence before the big bang, and what was called the big bang is simply the start of this episode of expansion which we are witnessing and trying to understand.
So you can find out what models other people are researching just by looking at online schedules of talks at the major international conferences that cover GR and cosmology. there are two main conferences, each of which is triennial (held every three years). they are called the Marcel Grossman meeting (they just had MG13 last month in Stockholm, over a thousand scientists participated) and the GR conference (GR20 will be held in Warsaw next year in early July. I guess attendance will be over 700).
MG13 had a special session devoted to nonsingular cosmology models. And it had four other sessions that were partly devoted to bounce cosmology and partly to quantum gravity and related stuff.
It is an active line of research and a lot of people are working on it. And a lot of people are interested in figuring out OBSERVABLE CONSEQUENCES of a bounce, traces or features of the CMB that they can look for in the sky.
the bounce idea is more popular with the professionals than your hypernova idea.
A hypernova is kind of like an explosion in preexisting static geometry---a fixed empty space.
That is not how they picture expanding geometry cosmic models. You know that GR is first and foremost a theory of dynamic geometry. It explains why geometry is (in many familiar situations) nearly Euclidean and why in other situations it is not. It describes how, if geometry is started off expanding it will continue although it may slow down. And the stuff, the matter, may not be moving in any ordinary sense, it may not be getting anywhere, just everything getting farther apart. Distances can expand uniformly without objects changing relative position. So it is that kind of distance expansion that they have to explain---not an explosion.
It turns out that if you quantize GR, get quantum versions of the equations of GR or of cosmology, gravity can turn repellent at very high density, so gravitational collapse leads to a rebound. A singularity never develops. So that is one version of nonsingular cosmo----one type of cosmic model. It is one quite a lot of people work on and that got discussed a bunch at the Marcel Grossman meeting in July.
It's still early days. There are no final conclusions about what was before the start of expansion and what gave it its big start. Personally I am not ruling anything out. I wouldn't even reject the idea of a hypernova, or that a collapse to a black hole caused a bounce resulting in a new expanding region of spacetime. At this point all the ideas are on the table AFAICS.
But stay tuned. Next year we will see what gets attention at the other big triennial meeting: GR20 in Warsaw. The schedule will be posted online. Also summaries of the talks. A lot of people want to know exactly what you are curious about: what could have led up to the start of this geometric expansion that we're part of.
You should realize that distances to most of the galaxies we can see with telescope are currently increasing faster than c. Geometric expansion can do that. Flying debris from an explosion can not. It's different.
