As I understand the big bang it was when an infinitely small and dense piece of matter in space exploded and s

Question

Thanks for the answers but I still don't really get how it happened. Where did everything come from? Where did the energy or light or even the black holes come from? It all has to have a cause, energy, light even black holes have to have a cause. I make no claim to be an expert on the subject but nothing I've ever read has offered a really logical explanation of where everything came from. Maybe we'll never know. thanks

Answer 1

Interesting question, apparently not one that can be answered.

Answer 2

Sort of.  This infinitely dense and infinitely small 'thing' is referred to as "the singularity".  It didn't quite explode -- for reasons not quite understood, this matter was suddenly pushed outward, beginning:

A) The expansion of the universe

B) Time flowing forward

C) Reality as we currently know it -- the laws of physics, etc.

Answer 3

No explosion.

No matter.

Pure energy at an energy density (a.k.a. temperature) so high that every single point of the universe would have been a black hole.

Expansion began and cooling came with it.

At the Planck Time (the earliest time at which science can still make sense of it), the temperature was as described above.

During the first second, the bosons "condensed" -- they are the particles that mediate the forces (e.g., photons, gluons).

Then came the leptons (e.g., electrons), the neutrinos and the quarks, immediately captured by the gluons and assembled into hadrons (e.g., protons, neutrons).  The temperature was so high that these things kept plowing into each other to fuse and form heavier nuclei (deuterium, helium, beryllium... but not much higher -- carbon, nitrogen and oxygen, for example, did not have time to form).  This is the first step where we could speak of "matter".

This lasted 3 minutes.  After that, the temperature was too low for fusion to continue, but still way too high for chemistry to begin (the photons were still too energetic to allow electrons to orbit protons).

After 300,000 years (yes years), the temperature finally dropped to 3000 K (4900 F) and electrons could finally remain in orbit around protons.  Neutral atoms began to form and the universe suddenly became transparent (emission of what we now see as the Cosmological Microwave Background radiation).

From this point on, chemistry -- atomic interactions at the electron-valence level -- can begin.  This is what most of us would call matter (as opposed to plasma, for example).

Where did the original "unbound" energy density come from?  The Big Bang theory does not say, and it cannot say -- it can't probe back before the Planck Time at

0.000000000000000000000000000000000000... sec.

(43 zeros after the decimal point, then a five)

At that time, the temperature was

1.416 785 × 10^32 K

141,678,500,000,000,000,000,000,000,00... K

(a total of 33 digits, counting the 1 at the start)

(to have a rough idea in F, just multiply by 2 -- at this level, who really cares?).

In physics, it is impossible to understand any higher temperature.  This does not mean that we don't know enough.  This means that we know it is impossible to use our understanding of physics at any higher level of temperature.

Therefore, we cannot understand what the universe was like before the Planck Time.

But we know that it was not matter and we know that it was not an "explosion".

Answer 4

This bit about the start of the Universe being small isn't right either.  The Universe had to start out at least as large as the Visible Universe is today.  Otherwise, the light that is now the Cosmic Microwave Background would have already passed us by.

The Universe started out very hot and very dense.  One estimate is that all the matter in the current visible Universe started out in a volume the size of a proton.

Check out the Scientific American article.

Answer 5

Most scientists would disapprove of your word "exploded" although that was the original concept of the French priest who developed the idea.  But yes, that is about it, although you are leaving a lot out including faster than light expansion for a short period of time.

  I stand corrected.  At the very beginning we are not talking about matter.  Just energy.  Then matter and antimatter formed and what we have left is the slight imbalance of matter that existed.  The rest vanished back into energy by self annihilation.  All of this took place very quickly.  Sorry about my mistake.

Answer 6

Your understanding is incorrect in several ways. It wasn't  "a piece of matter", it was pure energy. It wasn't in space, the expansion created space, and is doing so still. And it wasn't an explosion, but an expansion.

Other than that, exactly right. It's called the big bang.