James Webb telescope . Seeing the first stars?

[Swinglowandslow]

Just read an article on BBC news app which is about the above shortly being launched into orbit a million miles from Earth .
It will be a wonderful achievement, but the article make a statement that I cannot see the logic of.
It describes how the telescope sees the first stars, the moment when they flickered into light.
Quote
"It should be possible for Webb to see (or least detect a faint glow from) the moment when the darkness ended and those first stars flickered into life"

I know the light from the stars will,have taken billions of years to reach us, but why is that "the moment when the darkness ended" that we will see.
When we see the light from our sun, it is the light which emanated from the sun eight minutes ago.
We do not see the light which emanated from the sun yesterday, or last year or last century?
So, whatever light we see from these stars billions and billions of miles away is not likely to be the first light they produced, is it?
Journalistic licence, or something I don't understand?
Comments?

 

[Piece]

I think they mean we can view the nurseries of stars, in the process of creation. It's not going to be a dramatic "light switch on" moment that you get with a supernova for example.

 

[Jimaroid]

J
I know the light from the stars will,have taken billions of years to reach us, but why is that "the moment when the darkness ended" that we will see.

There is always some journalistic interpretation, it's a complicated subject, but it's pretty much correct given the age of the universe. If it's observing infra-red from 13.5 billion years ago and the universe is around 13.8 billion years old it's correct in principal to call it the first light. That time is around the period the universe evolved from gassy soup to the formation of stars and galaxies.

One of the reasons Webb is so exciting is that in some ways we don't know what it's going to find. It will help prove and disprove theories on our understanding of the universe because it can see so far back in time.

 

[Swinglowandslow]

There is always some journalistic interpretation, it's a complicated subject, but it's pretty much correct given the age of the universe. If it's observing infra-red from 13.5 billion years ago and the universe is around 13.8 billion years old it's correct in principal to call it the first light. That time is around the period the universe evolved from gassy soup to the formation of stars and galaxies.

One of the reasons Webb is so exciting is that in some ways we don't know what it's going to find. It will help prove and disprove theories on our understanding of the universe because it can see so far back in time.

If it's observing light from 13.5 billion years ago, then, yes, the universe is at least of that age.
But, if we know that the light we are observing is from that distance away, that only tells us the minimum age, yes.?
E.g. We know ( somehow, I must admit I don't know exactly how, but I will look it up) that the light from our star takes 8 minutes to get to us.
That doesn't mean the star is 8 minutes old. It means it is at least that old.
We know , by observation that it's at least thousands of years old?,( being facetious to make the point), and science has determined it is a 4.5billion(solar system age) old.
The point I am making that the time it takes light to reach us cannot be the determinant of how old the source is? Could be a lot older , couldn't it?

 

[Piece]

If it's observing light from 13.5 billion years ago, then, yes, the universe is at least of that age.
But, if we know that the light we are observing is from that distance away, that only tells us the minimum age, yes.?
E.g. We know ( somehow, I must admit I don't know exactly how, but I will look it up) that the light from our star takes 8 minutes to get to us.
That doesn't mean the star is 8 minutes old. It means it is at least that old.
We know , by observation that it's at least thousands of years old?,( being facetious to make the point), and science has determined it is a 4.5billion(solar system age) old.
The point I am making that the time it takes light to reach us cannot be the determinant of how old the source is? Could be a lot older , couldn't it?

I think I get what you mean.

Astronomers also look at the light luminosity, spectrum and spin rate/motion of a star to determine it's approx. age. By comparing against a database of star observations, they can estimate the star age; e.g. blue end of spectrum means a hot, young stars, and the opposite end of the spectrum, red stars, in older age. Looking back in 13.5bn years, they'll be looking to see the blue end of the spectrum.

 

[bobmac]

If you ask around the US, about 40% still believe it's only 6,000 years old

 

[toyboy54]

If you ask around the US, about 40% still believe it's only 6,000 years old

Try the DUP in N.I.
Big fan Brian COX-The Planets and now Universe!
Somehow makes you realise how insignificant we are (or are we?) in the great scheme of things-just my opinion
Do you think there will be time for me to get to scratch before it all goes 'Tits up'?

 

[Foxholer]

If it's observing light from 13.5 billion years ago, then, yes, the universe is at least of that age.
But, if we know that the light we are observing is from that distance away, that only tells us the minimum age, yes.?
E.g. We know ( somehow, I must admit I don't know exactly how, but I will look it up) that the light from our star takes 8 minutes to get to us.
That doesn't mean the star is 8 minutes old. It means it is at least that old.
We know , by observation that it's at least thousands of years old?,( being facetious to make the point), and science has determined it is a 4.5billion(solar system age) old.
The point I am making that the time it takes light to reach us cannot be the determinant of how old the source is? Could be a lot older , couldn't it?

Observations of events on/by the Sun are indeed of what happened 8 mins ago (assuming your figures) - the time it takes for light to travel the 93 million miles involved. So if one wanted to see what was happening on the Sun 8 mins ago, then observing 'now' would be appropriate. Likewise, if we wanted to 'observe' what happened on the Sun 'now', we'd have to wait the 8 mins it took for the event to be 'transmitted' for observation (or more if the observation was made from significantly the 'other side' of the sun).
Calculations from several sources have deemed that our universe is around 13.5-13.8 billion years old (though there's at least 1, as yet unexplained, anomoly) , so looking at parts of the universe that are 13.5 to 13.8 billion years old should tell us what was happening then - i.e not long after the 'big bang'.

 

[Swinglowandslow]

Observations of events on/by the Sun are indeed of what happened 8 mins ago (assuming your figures) - the time it takes for light to travel the 93 million miles involved. So if one wanted to see what was happening on the Sun 8 mins ago, then observing 'now' would be appropriate. Likewise, if we wanted to 'observe' what happened on the Sun 'now', we'd have to wait the 8 mins it took for the event to be 'transmitted' for observation (or more if the observation was made from significantly the 'other side' of the sun).
Calculations from several sources have deemed that our universe is around 13.5-13.8 billion years old (though there's at least 1, as yet unexplained, anomoly) , so looking at parts of the universe that are 13.5 to 13.8 billion years old should tell us what was happening then - i.e not long after the 'big bang'.

Yep, that makes sense. But what "calculations from several sources" have deemed the 13.5 billion?
(Genuine question, I haven't yet looked it up)
I.e. When they see a star ( in another galaxy, say), how do they know how far away it is?
When they do know that, then obviously they can work out how long it takes for its light to reach us, but how does looking at a star tell us how far away it is? (Must look it up?)

Edit - yes, parallax, parsecs and SBF. Phew! Best of luck with that lot?

 

[Jimaroid]

If it's observing light from 13.5 billion years ago, then, yes, the universe is at least of that age.
The point I am making that the time it takes light to reach us cannot be the determinant of how old the source is? Could be a lot older , couldn't it?

Yes and no. Yes something needs to have existed prior to the first photons of light being emitted. No, it won't be a lot older in cosmological terms. Firstly because we have a reasonably good idea of how old the Universe is and secondly we have a good idea of when, how and how long it takes stars to form.

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.

Yep, that makes sense. But what "calculations from several sources" have deemed the 13.5 billion?
(Genuine question, I haven't yet looked it up)

We can extrapolate backwards based on the rate of expansion of the universe back to the big bang. Edwin Hubble (the telescope namesake) figured a lot of this and your other questions out by the way.
He determined the universe is expanding by measuring redshift of light, and that shows if stars and galaxies are moving towards or away from us.

I.e. When they see a star ( in another galaxy, say), how do they know how far away it is?

Combination of methods. You can measure nearby stars by simple triangulation by taking two observations. One in midsummer, one in mindwinter. Earth's position 6 months apart will give you a triangle and some simple maths.

Another method is colour and brightness of stars. These give you a relationship to distance.

 

[Foxholer]

Yep, that makes sense. But what "calculations from several sources" have deemed the 13.5 billion?
(Genuine question, I haven't yet looked it up)
I.e. When they see a star ( in another galaxy, say), how do they know how far away it is?
When they do know that, then obviously they can work out how long it takes for its light to reach us, but how does looking at a star tell us how far away it is? (Must look it up?)

This explains most of the first question...https://www.space.com/universe-age-14-billion-years-old
For the 2nd....
By using 'parallax', just as our brains do from input from eyes that a slightly apart, observations at extremes of Earth's orbit around the Sun provide slightly different angles, so distance to coincidence can be calculated.

 

[SwingsitlikeHogan]

Observations of events on/by the Sun are indeed of what happened 8 mins ago (assuming your figures) - the time it takes for light to travel the 93 million miles involved. So if one wanted to see what was happening on the Sun 8 mins ago, then observing 'now' would be appropriate. Likewise, if we wanted to 'observe' what happened on the Sun 'now', we'd have to wait the 8 mins it took for the event to be 'transmitted' for observation (or more if the observation was made from significantly the 'other side' of the sun).
Calculations from several sources have deemed that our universe is around 13.5-13.8 billion years old (though there's at least 1, as yet unexplained, anomoly) , so looking at parts of the universe that are 13.5 to 13.8 billion years old should tell us what was happening then - i.e not long after the 'big bang'.

To complete the 8min sum…93,000,000 miles at 186,000 miles/second.

 

[stefanovic]

The point I am making that the time it takes light to reach us cannot be the determinant of how old the source is? Could be a lot older , couldn't it?

The universe if formed 13.8 billion years ago should only be about 27.6 billion light years in diameter, but by the latest estimates it is about 90 billion light years in diameter (and counting).
Was there a faster than light expansion?
You need to also factor in dark matter, which we know little about other than it likes to hang out with star formations (galaxies).
Then there is gravitational lensing which dark matter may also play a part.
Another problem lies in the shape of the universe, which we don't yet know.
De-Sitter space would point to a spherical shape. Anti De-Sitter space would point to a saddle shape. Minkowski space would point to a flat universe.
What we know from Einstein is that space is curved.
And we don't what time is, either.

 

[Foxholer]

...
What we know...
And we don't...

And that is is the entire 'problem'/challenge!

 

[Piece]

The universe if formed 13.8 billion years ago should only be about 27.6 billion light years in diameter, but by the latest estimates it is about 90 billion light years in diameter (and counting).
Was there a faster than light expansion?
You need to also factor in dark matter, which we know little about other than it likes to hang out with star formations (galaxies).
Then there is gravitational lensing which dark matter may also play a part.
Another problem lies in the shape of the universe, which we don't yet know.
De-Sitter space would point to a spherical shape. Anti De-Sitter space would point to a saddle shape. Minkowski space would point to a flat universe.
What we know from Einstein is that space is curved.
And we don't what time is, either.

It's the space that is expanding, giving the impression that the furthest galaxies are moving away from us at faster-than-light speeds when their velocities are "measured".

 

[Foxholer]

It's the space that is expanding, giving the impression that the furthest galaxies are moving away from us at faster-than-light speeds when their velocities are "measured".

Perhaps; perhaps not. I'm not sufficiently 'up' with 'modern' knowledge; though my (late) brother had the opportunity to 'investigate' some of the mathematical issues under Prof Kerr many years ago.
But fwiw... How can we see, those 'furthest galaxies' if they are moving away from us at faster-than-light velocities - even if that's only an 'impression'

 

[Tashyboy]

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.

 

[backwoodsman]

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 ...

 

[toyboy54]

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

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 ...

Aren't we all?? puzzled/confused? Trying to get your head round this just leaves you frustrated at the enormity and time scales involved ( not being flippant but it surely easier to understand Einstein's Theory Of Relativity for simpletons such as I)

 

[Jimaroid]

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?

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.