Olbers paradox, why the night is ... black

[nlc]

The Big Bang was made of energy, at a theoretically zero volume and at an infinite temperature (I insist on the theoretically, because in reality there was certainly a limit).

We agree, but if there is a limit, what is behind it, that is the question, and it is this notion that makes you dizzy !!

To be in the middle of something you need a preliminary space ... which did not exist!

This is the concern, how is it possible that nothing exists, and that suddenly everything starts to exist ...

Well if at the start the universe was concentrated in an infinitely dense and hot point, why did it suddenly expand?

This is still unknown, why a volcano explodes?

Your comparison with the volcano does not seem great to me, if the volcano explodes, we know why, overpressure!

You have to know what we are talking about, what is time?
Has time always existed?
Has time had acceleration or even deceleration phases?
The notion of beginning and end requires time, except if we admit that time appeared at a time 0, there can be no "before", unless invoked a pre-time, or an a-time , a kind of eternity that escapes all calculation.

In my opinion time has always existed since otherwise we would never have arrived there !! Because if there is no time, time has no reason to start at a specific time. It is almost as paradoxical and fascinating as the fact that infinity can exist.

The fact that there was a universe in contraction does not invalidate the fact that our current universe is expanding.
Not having all the data, we do not know if this is possible or not.

In any case, I really think I read somewhere that against all odds the expansion of the universe was accelerating, how is this possible since it contradicts the very principle of gravity and mutual attraction of the masses?

[sen-no-sen]

This is still unknown, why a volcano explodes?

Your comparison with the volcano does not seem great to me, if the volcano explodes, we know why, overpressure!

The volcano explodes due to an overpressure, ok, but caused by what?

The gases following high temperatures, themselves caused by the degradation of radio-elements and friction in the earth's crust etc ... if you go back as far as possible you arrive ... at the big bang.
The aim of science being to go always further, the ultimate limit for the moment is the big bang.
As with volcanic eruptions where we used to think it was divine anger, science has found explanations, we may one day find an explanation for the big bang.

In my opinion time has always existed since otherwise we would never have arrived there !! Because if there is no time, time has no reason to start at a specific time. It is almost as paradoxical and fascinating as the fact that infinity can exist.

As said above, don't always or never say!
Can you give me the definition of the word always? What does the term always depend on?
Do you think the time is absolute?

In any case, I really think I read somewhere that against all odds the expansion of the universe was accelerating, how is this possible since it contradicts the very principle of gravity and mutual attraction of the masses?

What you have read is quite correct, the Universe is indeed expanding, we eventually speak of "Big Rip" (great tearing) as a possible finality of the universe.

[nlc]

one day we may end up finding an explanation for the big bang.

Or not

As said above, don't always or never say!
Can you give me the definition of the word always? What does the term always depend on?
Do you think the time is absolute?

Time is subjective, but if there is a starting point for time, how was the clock started? In my opinion the paradox is that if there was no time, there could not have been a starting point in time !!

What you have read is quite correct, the Universe is indeed expanding, we eventually speak of "Big Rip" (great tearing) as a possible finality of the universe.

Yes it is expanding, we have known this for a long time, but the novelty that I have read is that the expansion is accelerating rather than slowing down.

[sen-no-sen]

one day we may end up finding an explanation for the big bang.

Or not

Or not indeed!

Time is subjective, but if there is a starting point for time, how was the clock started? In my opinion the paradox is that if there was no time, there could not have been a starting point in time !!

It is indeed the theory of the paradox of Zeno, the more one approaches the "zero moment", the more this one "escapes" without ever being able to be reached, it is a theory defended by Thibault Damour et Marc Henneaux.

Time is not a subjective given, Einstein has demonstrated the concept of space-time and the influence that gravity has on it.
For example, time does not "flow" in the same way at sea level or at the top of a mountain (the differences are obviously imperceptible on the human time scale).
However in a logic of block universe, time does not exist in the way that one could think it according to our daily logic ...

[sen-no-sen]

A video conference to see absolutely on ... Time:

The two speakers: Etienne Klein and Marc Lachièze-Rey:

http://www.cea.fr/recherche_fondamentale/le_temps_entre_realite_et_illusion

[nlc]

I'm trying to watch this tonight, for now ...... no time !!