Big Bang..not so much?

[gaseous (Patrick)]

Originally Posted by Stonius

If you take the current rate of expansion and perform regression analysis you end up with the big bang. BUT this makes the rather big assumption that the universe's expansion has always accelerated at that rate.


Maybe the universe expanded differently when it was younger? Maybe the laws of physics change over time? There's no reason they have to be static. We assume that they are, but over timescales that big, could we detect the difference? (Or maybe we're just beginning to, with the JWST).


I'm the opposite of that guy from the A-Team. I *like it when a plan doesn't come together - because that's where the interesting stuff happens.


:-)

Yes, and there are still two (at least) schools of thought/calculations regarding the expansion rate of the universe, and their margins for error don't overlap, so there would appear to be something being missed somewhere.

[SB (Chris)]

They say we are looking at galaxies at a time of the early universe. however if we came from the same big bang then surely the light from those ‘early galaxies’ would have passed us ages ago? Did we expand from the same point?

[bojan]

Err.. Not quite.. You forgot about Inflation..
Space expanded with speed much faster than light, and that carried us away from the rest of the early universe. That is how the light from those places is reaching us now.

[xelasnave]

Originally Posted by bojan

Err.. Not quite.. You forgot about Inflation..
Space expanded with speed much faster than light, and that carried us away from the rest of the early universe. That is how the light from those places is reaching us now.

Good morning Bojan thank you for contributing to this thread.

I hope you and yours are all good.

Are you able to tell us the size of the Universe immediately prior to inflation and immediately after?

Alex

[bojan]

Originally Posted by xelasnave

Good morning Bojan thank you for contributing to this thread.
I hope you and yours are all good.
Are you able to tell us the size of the Universe immediately prior to inflation and immediately after?
Alex

Hi Alex,

I am OK :-)

Have a look here...
Universe was ø10e-29 metres before and ~ø9 metres when inflation ended.

[bojan]

Also, see Wikipedia here.

[xelasnave]

Originally Posted by bojan

Also, see Wikipedia here.

Thanks Bojan...what I looking for was your personal description that you might give to a grand child or an ignorant layman using fruit

Alex

[Constant (David)]

Originally Posted by bojan

BTW...

I found the Sabine Hossenfelder lectures on the subject very interesting..

Yes, she's an outstanding communicaror not shy of dipping into some harder science, she's no Neil Degrasse Tyson. In my humble opinion we've too many Tysons, even our wonderful Dr Carl falls into the "light" camp. They've both done great things, however as the general level of science literacy improves we need more Sabine's.
DR Sagan will always be on a different level as he did it first, capturing generations while inspiring younger science minds.