James Webb telescope . Seeing the first stars?

[Swinglowandslow]

Firstly because the problem we’re setting ourselves is within the observable universe, the extremity of what is observable is limited by how far light can travel or has been able to exist in the age of the universe since the Big Bang.

But if you think a little further, the universe must be bigger than the observable universe because every point in the universe has its own observable universe.

That is the type of thinking that leads to the multiple and infinite universe theories. We don’t know how big the universe really is, maybe infinite, because we can only see as far as a signal can travel at the speed of light since the Big Bang.

It’s all quite mind bending. A lot of it is measurable by simple observation, a lot is theory and we may never know for certain.

And yet many ( not me) think we are the only life in all that?
As you say, mind bending.

 

[IanM]

Only 500 years ago they were having this sort of discussion about what was over the visible horizon!! ?

 

[Smiffy]

What was there before the "big bang"????

 

[IanM]

What was there before the "big bang"????

The whole universe was in a hot dense state.... ?

 

[Tashyboy]

The whole universe was in a hot dense state.... ?

bit like the forum before fragger came along.

 

[Robster59]

I saw a piece on Facebook a few weeks back which I tried to put on here. It showed the size of planet earth Against other planets in our solar system, then the size of our sun, the size of our galaxy.Then other galaxies. It was simply amazing.

Sounds like the Total Perspective Vortex. Beware!

 

[Maninblack4612]

How come the light we detect from the furthest stars/galaxies isn't just half as old as the universe? (Or thereabouts).

After all, at the birth of the universe, the whole of it was very small - so the light generated at that time would have "arrived" quickly. The light we detect now is very old because it's come from a long way off. But surely the source of the light must have taken an equal, very long, time to get that far away in the first place?

I very much doubt my non-understanding of this matter undermines the work of the pantheon of physicists and astrophysicists who've gone before, but nonetheless I am puzzled ...

Is your problem something to do with the fact that if a body is travelling away from you at a high speed the light from it arrives in exactly the same time as it would if the body were stationery. Einstein proved this & concluded that, for this to be true, time on a body travelling at speed passes more slowly than on something stationary. This fact has to be taken account of when operating satnavs because of the speed of the satellites. Of course, nothing is actually stationary. The earth is rotating at 1,000 mph as well as moving around the sun. The whole solar system is moving around inside the Milky Way, which itself is moving. It's the speed of something relative to something else that matters, hence the "theory of relativity". A fascinating subject.

 

[SaintHacker]

The difficulty is that in cosmology the numbers are so incomprehensively massive, a million years for a star to form is effectively nothing at the scale of the universe.

Ah, something else thats quicker than my mrs trying to reverse park the car...

 

[bobmac]

Evolution is beautiful

<blockquote class="twitter-tweet"><p lang="en" dir="ltr">In Bristol Harbour right now an aquatic species of lorry is trying to climb onto land for the first time<br>Evolution is beautiful <a href="https://t.co/HeiwqQfcvJ">pic.twitter.com/HeiwqQfcvJ</a></p>&mdash; Simon Clark (@simonoxfphys) <a href="

https://twitter.com/x/status/1451123251678175233

">October 21, 2021</a></blockquote> <script async src="https://platform.twitter.com/widgets.js" charset="utf-8"></script>

 

[Tashyboy]

Sounds like the Total Perspective Vortex. Beware!

It’s not. But Al have a good peruse of that whilst sat at hospital. Am sure the piece I saw was by a Scandinavian guy.

 

[Tashyboy]

Is your problem something to do with the fact that if a body is travelling away from you at a high speed the light from it arrives in exactly the same time as it would if the body were stationery. Einstein proved this & concluded that, for this to be true, time on a body travelling at speed passes more slowly than on something stationary. This fact has to be taken account of when operating satnavs because of the speed of the satellites. Of course, nothing is actually stationary. The earth is rotating at 1,000 mph as well as moving around the sun. The whole solar system is moving around inside the Milky Way, which itself is moving. It's the speed of something relative to something else that matters, hence the "theory of relativity". A fascinating subject.

WHS ain’t that bad after all ??

 

[Maninblack4612]

WHS ain’t that bad after all ??

Not as easy to understand

 

[stefanovic]

The universe is big. It's very big and it's all curved space which is what we call gravity.
You can fit a million earth's inside the sun, and it's still curved space.
'There is nothing in the world except empty curved space." (John Wheeler).
We understand only 4% of what the universe is made of. The rest is dark matter and energy which we don't understand.
There are light stars and there are dark stars which emit no light.
The universe may have come from a black hole.
We probably live in one. Take away the stars and it's all black.
One of these smaller black holes will pull on our solar system one day and cause total destruction.

 

[Tashyboy]

The universe is big. It's very big and it's all curved space which is what we call gravity.
You can fit a million earth's inside the sun, and it's still curved space.
'There is nothing in the world except empty curved space." (John Wheeler).
We understand only 4% of what the universe is made of. The rest is dark matter and energy which we don't understand.
There are light stars and there are dark stars which emit no light.
The universe may have come from a black hole.
We probably live in one. Take away the stars and it's all black.
One of these smaller black holes will pull on our solar system one day and cause total destruction.

I thinks it’s always good to finish on a positive ???

 

[Smiffy]

"Two possibilities exist. Either we are alone in the universe or we are not. Both are equally terrifying"
Arthur C. Clarke

 

[Deleted member 29109]

Why does E=mc2 by Brian Cox is a good read. It does a reasonable job of explaining lots of complex things in simple terms.

 

[stefanovic]

I thinks it’s always good to finish on a positive ???

"If a black hole like Cygnus X-1 were to stray near the Solar System, within a light-year or so, its gravity would cause chaos.
The orbits of the outer planets and comets would be significantly and possibly disastrously altered, and this would in turn threaten the orbits of the inner planets and even the Sun."

Not to mention dark matter.

If the Milky Way passed through an area of dark matter it is likely that it would disrupt the Oort Belt of comets and send one spiralling through the solar system to smash into the earth.
Should we be worried? Definitely. 65 million years ago the dinosaurs were probably wiped out this way.
But I hear you say, it would never happen again!
Wrong. The Tunguska event in Siberia 100 years ago was quite possibly caused by something like this.
There is no other reason why a comet's regular orbit should be disturbed by anything else.

(Dark Matter and the Dinosaurs by Lisa Randall).

 

[Foxholer]

...
One of these smaller black holes will pull on our solar system one day and cause total destruction.

I seriously doubt that'll happen before our Sun collapses into White Dwarf then explodes into Red Giant - but I doubt I'll be around, as that'll be in about 4.5 Billion years. The nearest star (appropriately named Proxima Centauri) is 4.2 Light Years away, while the nearest Black Hole seems to be 1500 LYs away, so (especially as it's only about 3 times the mass of the Sun) is unlikely to 'suck us in', especially as the universe still seems to be expanding!

 

[Foxholer]

...The Tunguska event in Siberia 100 years ago was quite possibly caused by something like this.
...

That's NOT the recognised belief of the cause of that event!
NASA has recently launched a 'Planetary Defense' test satellite with the purpose of 'bumping' an asteroid of its existing course to check/confirm the viability of doing so should a future possible collision be recognised.
Btw. Why would any heavenly object 'stray' anywhere?! Even within the existing recognised 'laws of motion', such a thing has not been observed.

 

[Smiffy]

Say what you like... it's all fascinating stuff but it makes my brain hurt.
???