Whenever a cosmologist says “Universe born after Big Bang” I was wondering what came before it. Finally found a good forum/blog to discuss it.
Looking Forward to Best Results/Answers.
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This is an interesting question. This is what I know:
When the big bang happened, the universe as we know it, emerged from a singularity which had infinite density and gravity. It was only after this that space and time as we know them today started to exist.Therefore, you cannot have “before” the big bang.
What triggered this big bang…well nobody really knows.
I’m hoping @kishan and @adhvaidh.maharaajan will share more light on this.
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@siva anna, Can we try to approach this from the different end,like considering a different theory like Big Bounce which shows some light on Pre–Big Bang cosmology.
Thank You for your prompt reply.
I’m new to this forum. Not sure if I can share youtube links, but here is a video on how we arrived at the big bang theory and the history of it.
It talks about the prevalent ideas about how the scientific community had considered different hypothesis like steady state, inflation, etc and how different kind of observations confirmed that it is very likely the universe began from a big bang.
To answer your question in particular: the current theory which is widely accepted by the scientific community as of today is that space and time itself formed at the big bang from a singularity. So the question of what was before the big bang is itself not a correct question! It’s like asking what’s north of north pole.
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hey!
that is such an interesting question…
but as @Pritam_Gembali says, if before Big Bang does not exist , we ought to direct more of our resources to see what our space is expanding into right? - because it is expanding and at an accelerated speed!.. what exists outside of vaccum which is not empty space itself?
I think this is the closest version of the question you have asked that should actually have an answer.
-just curious
edit- i also think this is the kind of question that can go in the astrophysics section…
Hey guys,
I recently joined this forum. As @siva says, I too have read a few articles and books which say that space and time itself began with the big bang. So there is no concept of time before that event. Hence the word ‘before’ doesn’t apply.
I have a speculation or even a fancy if you may. Looking at many things around us starting from day- night, seasons, planet orbits, star life cycle etc, it seems probable that universe itself could have a ‘life cycle’. Big bang happens (no one knows why) and everything gets scattered. But slowly gravity pulls back everything into a big crunch. Then a big bang repeats. Most of the galaxies have a gargantuan black hole at the centre and all the stars revolve around it. Doesn’t it seem probable that gradually, all stars, planets, dust of the galaxy will collapse into that black hole? And many such black holes come close to each other and collapse into a singularity leading to the big crunch?
I writing this ‘almost sci-fi’ speculation inspite of reading articles that big crunch is not going to happen according to many studies and all matter (infact space itself) is going away and away from each other (a cold end). I think even the 2011 (iirc) nobel prize for physics was awarded for this exact same thing. But I somehow can’t help but think that we have probably observed only some local phenomenon in a very vast universe (leading to the conclusion of no big crunch) and there is still a chance for a big crunch.
Would appreciate any comments.
Cheers!
Anirudh.
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Actually, there is one problem with the understanding of Big Bang. What do you mean by Big Bang? According to experts big bang is not the beginning of the universe.
Here are my two cents (or paise?) on this as someone who works on cosmology:
Whenever cosmologists talk about the Universe, they often refer to a “metric of the Universe” aka the FLRW metric. A metric is simply a mathematical construction to define the boundaries of the Universe in both space and time (similar to say latitudes and longitudes, which are mathematical constructions describing the Earth).
Within this framework, the Universe is assumed to have started from a singularity (i.e., a point of infinite density) and expanded to have a finite density (objects such as you and I have finite densities). In this theory, time does not exist before this singularity, and t=0 itself is at the beginning of expansion. Furthermore, it is not to be understood as the Universe expanding into an encompassing object (i.e., not like some gas expanding in a room). Rather, the FLRW metric explains that space itself expands and stretches. So nothing exists outside the Universe, similar to how there’s nothing north of the north pole. It is a mathematical boundary beyond which things do not exist.
Now, that’s the theory - and it obviously has flaws and problems. In fact, the origin and evolution of the extremely early Universe are poorly understood as this theory does not include the effects of three fundamental forces of nature (strong nuclear force, weak nuclear force, electromagnetism), nor quantum mechanics. It only covers gravity, one of four fundamental forces. So there’s a lot left to be found. In conclusion, we can really only be confident about this - the Universe was once a hot ball of gas and expanded over billions of years to form stars and galaxies. How precisely it got to that state and where it all originated is an ongoing research problem. I hope this helps! 
References for further reading:
FLRW metric
[Big Bang theory - misconceptions]
(Big Bang - Wikipedia)
Lambda-CDM model of cosmology
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Nice speculation Anirudh. I particularly liked the usage of the word ‘local’ to describe our observable universe. For all we know, what we consider the universe could be just a small part of something bigger. That keeps the big bang theory local too. And the best description of all our understanding might still be ‘we don’t know, for sure’.
So as a science student … after analyzing with AI models and research papers (including wiki) this is what i have come up with (may be as a solution)
"According to current scientific understanding and cosmology, the concept of “before” the Big Bang is not well-defined. The Big Bang theory describes the origin of the universe as we know it, where all matter and energy were concentrated in an extremely hot and dense state. The universe then began expanding and cooling, eventually leading to the formation of galaxies, stars, and other structures over billions of years.
However, the Big Bang theory does not provide an explanation for what existed before this hot and dense state. The singularity that marked the beginning of the universe is a point of infinite density and gravity, where the laws of physics as we understand them break down. Our current scientific models are unable to describe the conditions or events prior to the Big Bang.
It’s important to note that the concept of time as we perceive it may have also originated with the Big Bang. Therefore, asking what came before the Big Bang may be a fundamentally flawed question, as time itself may not have existed in the way we understand it before the universe’s emergence.
While there are various theories and speculations, such as the idea of a cyclical universe or the possibility of a multiverse, these ideas are still highly speculative and not yet supported by conclusive scientific evidence. The origin of the universe and what, if anything, preceded the Big Bang remain open questions in cosmology, and ongoing research and scientific investigations aim to further our understanding of these fundamental mysteries."
Hope this helps !
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I read someone’s explanation of the universe and big bang. there is universe and observable universe, our observable universe was created by big bang, and our observable universe is part of the universe and multiple observable universe exist/ multiple big bang occurs. there is no proof for this just speculation
@Thiyagarajan you’re right. Especially on this,
asking what came before the Big Bang may be a fundamentally flawed question
Right now, Im inclined to believe the String Theory which hypothesises that Big bang was the result of a quantum fluctuation in a multidimensional universe giving rise to our 4 dimensional universe (Space + Time). The theory also plays well with the idea of multiverse and our standard model of particle physics seems to fit in as well.
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Here’s a simplified explanation (Non-scientific):
Imagine you’re on a mission to reach the North Pole by walking. You ask someone for directions, and they point you towards the north. You start walking in that direction. Along the way, you encounter more people and keep asking the same question, adjusting your course based on their directions.
As you continue walking further north, you eventually reach the North Pole. At this point, if you were to ask anyone for directions to the North Pole, it wouldn’t make sense because you’re already there.
This analogy applies to the question of what came before the Big Bang. As we trace back in time, we approach the very beginning of the universe. However, reaching that point is like arriving at the North Pole. It signifies the starting point of time, and there is no “before” that can be comprehended.
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