Why is the Big Bang shown always directional, instead of globally?

[two OLD 2 care]

TL;DR Summary

Why is the Big Bang shown always directional, instead of globally ?

I`m new to physics, but old to the plant ( 70 )
My question is 1) why wouldn`t the universe have evolved ,
( change from little / big ), leaving a bit of both , i.e. 2 theories ?
2) Why is the Big Bang always depicted, directionally ?

 

[anorlunda]

why wouldn`t the universe have evolved ,
( change from little / big ), leaving a bit of both

It is bigger now than it was before. But we think the universe is infinite in extent. If you think about it more, you should see that nothing finite in size can ever grow to infinite size. Nor can something infinite in size ever have been finite in the past.

Why is the Big Bang always depicted, directionally ?

The early universe was also opaque to light. So here is a more realistic picture of it. Not very interesting huh?

 

[PeroK]

Summary:: Why is the Big Bang shown always directional, instead of globally ?

I`m new to physics, but old to the plant ( 70 )
My question is 1) why wouldn`t the universe have evolved ,
( change from little / big ), leaving a bit of both , i.e. 2 theories ?
2) Why is the Big Bang always depicted, directionally ?

I'm not sure I understand either of these questions.

 

[two OLD 2 care]

It is bigger now than it was before. But we think the universe is infinite in extent. If you think about it more, you should see that nothing finite in size can ever grow to infinite size. Nor can something infinite in size ever have been finite in the past.
The early universe was also opaque to light. So here is a more realistic picture of it. Not very interesting huh?

View attachment 293563

You didn`t get my drift.
I was axing, why should we assume the universe back then is what
we ended up with along with some flak from before ?
Maybe the elements change or gave ( birth ) to or decayed from what was once. Leaving us with a open path of the physics tree.

 

[berkeman]

You didn`t get my drift.
I was axing, why should we assume the universe back then is what
we ended up with along with some flak from before ?
Maybe the elements change or gave ( birth ) to or decayed from what was once. Leaving us with a open path of the physics tree.

What reading have you been doing about these questions? Hopefully we can point you to some better sources of information to read...

Here is a reasonable place to start:

https://en.wikipedia.org/wiki/Big_Bang

How about you read through that introductory article and come back here with any specific questions you have about that reading...

 

[Torbjorn_L]

Reading the Wikipedia article and come back is likely the best idea. My naive attempt to riddle the second set of questions is that there is a confusion between biological evolution theory and cosmological evolution of the expanding universe. This is a confusion deliberately sourced by creationists, and one may meet it in various places where it doesn't belong (such as on science sites).

The former theory is the theory of the observed biological evolution process, which do have pathways and splits and forms phylogenetic trees. The latter is a completely different process, best described by likewise observed inflationary hot big bang theory in US National Academy of Sciences Astro2020 Decadal Survey* - a cosmological inflationary expansion process [a "Lambda expansion" if you want to analogize] followed by a Lambda-Cold Dark Matter expansion process.

*It reads as the committee result as it is, since the cosmological report can't come out and clearly separate the two eras albeit they do admit that inflation happened before the now properly labeled Hot Big Bang and that unless the expansion was eternal - the naive result in the observed flat space topology - it may explain how expansion started. I think I will call the NAS Astro2020 description the "Bug Bang" because the mental gymnastics of conservative cosmologists bugs me.

 

[Drakkith]

Maybe the elements change or gave ( birth ) to or decayed from what was once. Leaving us with a open path of the physics tree.

It's certainly possible that the early universe was very, very different from what we see today. And scientists have various theories about this possibility. The problem is that if we can't observe it, it's nearly impossible to make a working model or theory on it.