Astronomy/big bang help needed

https://www.bbc.co.uk/news/articles/cjeenyw8rd2o

So BBC reporting the Webb telescope has found a galaxy formed just after (ok 200+million years) the universe was formed. They state the Big Bang was 13.8 billion years ago.

Now I understand that we see the galaxy how it was so long ago because the speed of light can be measured so it takes an exact time to reach us but…

Help my head understand how they know it started 13.8 billion years ago. How do they arrive at that or any other figure.

Very basic version, they can tell the universe is expanding. This is because of the ‘red shift’, things which are moving away from us look more red as this elongates the light’s wavelength a little. From this they can work out how fast near and far things are moving away.

Therefore is the universe is expanding then in the past it was smaller. So extrapolate backwards to when it was very, very small, and it was all in the same tiny space about 13.8bn years ago..

Someone will be along with more detail shortly but that’s the jist of it

This^^^^

Dr Brian Cox once shut down a flat earther with, and I’m paraphrasing here, “we know the the Big Bang happened, because if we look we can see it!”

A massive telescope, the James Webb in this case, and a huge tape measure

There’s a good Netflix (if you have Netflix) documentary “Unknown: Cosmic Time Machine” that I just about managed to follow. Disappointingly they don’t show the tape measure 🙂 https://www.netflix.com/gb/title/81473680

This isn’t a bad explainer if you already have a grasp of the basics

Well, my ambition to be the next Brian Cox has been dashed then as if seeing colours is key then being colour blind is a major handicap 😢

Thanks for the explanation, a mystery solved….now for how did the universe start thoughts. Paraphrasing the Foos

“Something from nothing” 🤯

Although that video does help ⬆️ but where did the electrons/particles that caused the BB come from, what did they exist in?

Its black holes all the way down

What’s the universe expanding into though?

I listen to infinite Monkey Cage a lot and I’m still thick.

Prof Jim Al-Khalili explained it all brilliantly in a book that explained why there are black bits between stars.

It’s not as obvious as you may think.

Help my head understand how they know it started 13.8 billion years ago. How do they arrive at that or any other figure.

The fundamental first step is using a figure a decimal point in it make it look like you you calculated it rather  rather than it being a guess. 🙂

I’ve heard Brian Cox describe events as happening in the ‘first two billionths of a second after the Big Bang’ which to be frank stretches my credulity a little. But I suppose we’re trying to impose our own ideas and sensations of time, space and matter onto an event and moment where the reality of everything was entirely different.

It’s sort of pointless describing these things in terms of measurement because a billion of anything is something we can’t comprehend – all re are really doing is stating the order that things occurred in. A year, a second or billions or billionths of either don’t have any meaning when you’re describing something where the matter and material of everything is outside of our understanding. We couldn’t exist in those conditions to observe them – we only have senses that describe the matter of the of the universe around us  as it is now now – we wouldn’t be able to see, hear or feel a universe as it was them.

I am no expert. (Know just enough to get it properly wrong)

Something to do with Wein’s and Stefan’s laws combined which use known data to extrapolate back.

The ratio of the peak intensity wavelength of light emitted from the galaxy to our sun is equal to the ratio of greater than speed of light the galaxy is moving.

Measure the parallax angle over a year and you know how far it is away. Or use Hubble constant.

@richmtb

I watched that the other week and it melted my brain. Understand the concept but the fact that it is a theory but could possibly be true is just mind-blowing

“What’s the universe expanding into though?”

Into nothingness I believe.

Now *that’s* a mindfeck !

I like to think I’m fairly scientifically literate until I start comprehending the universe. Then I hear ‘something something non-Newtonian’ or ‘something something bending space-time/gravitational waves’ and decide to crawl back into the ‘thick hole’.

My question, following on from the OP. As we can now look back to only 290 million years after the BB, if we reach the point where we can ‘just look a bit further’ will we eventually be able to see the actual BB itself? Or possibly the very first galaxy ever formed, and its creation? If everything in the Universe was formed in the BB then if we ever achieve the point of seeing the BB in the far distance, are we looking at ourselves being created?

*shuffles away to find a dark (matter) room for a nap

I listen to infinite Monkey Cage a lot and I’m still thick.

That’s cos every interesting answer from guests and/or Cox are routinely shouted out by that halfwit Robin Ince trying to make one of his abysmal “jokes” 🙄

I watched that the other week and it melted my brain. Understand the concept but the fact that it is a theory but could possibly be true is just mind-blowing

It is of course all just speculation.  I mean its a really clever trippy idea and makes you think about the limits of reality but none of it is testable, things beyond or before the Big Bang are fundamentally unknowable.

My question, following on from the OP. As we can now look back to only 290 million years after the BB, if we reach the point where we can ‘just look a bit further’ will we eventually be able to see the actual BB itself? Or possibly the very first galaxy ever formed, and its creation? If everything in the Universe was formed in the BB then if we ever achieve the point of seeing the BB in the far distance, are we looking at ourselves being created?

We can actually “see” back to about 300 thousand years after the Big Bang.  But “seeing” further brings up all sorts of fundamental questions about what does “seeing” even means.

What we see at 300 thousand years after the Big Bang is the Cosmic Microwave Background (CMG).  As far as we can tell its impossible to “see” any further back as photons didn’t exist before this time.  It might be possible that some future tech using gravity waves might be able to probe further back in time but that would probably involve understanding quantum gravity which has eluded us so far.

There’s also the problem of seeing further because space itself is expanding. So if light from the furthest thing is travelling at the speed of light but things beyond that are moving away from us then the light from those won’t ever reach us as it isn’t fast enough, AIUI that is what defines the limit of the ‘observable’ universe. Beyond that, who knows. Nothing? Another universe? The rest of reality?

Olbers’ paradox.

“What’s the universe expanding into though?”

the one next door

There’s also the problem of seeing further because space itself is expanding. So if light from the furthest thing is travelling at the speed of light but things beyond that are moving away from us then the light from those won’t ever reach us as it isn’t fast enough, AIUI that is what defines the limit of the ‘observable’ universe. Beyond that, who knows. Nothing? Another universe? The rest of reality?

What really interesting is that the rate of expansion is increasing – so called “dark energy” is the cause but really no one has any idea why “dark energy” its basically just a place holder for our utter ignorance, cosmologists might as well have just said “Here Be Dragons”

This leads to the fact that billions of years in the future all galaxies that aren’t gravitationally bound to ours will disappear from view completely and all we will ever be able to observe is our local group.  We’d never be able to discern anything about the larger universe or its origins.

@sheldon @leonard @raj @howard

This leads to the fact that billions of years in the future all galaxies that aren’t gravitationally bound to ours will disappear from view completely and all we will ever be able to observe is our local group. We’d never be able to discern anything about the larger universe or its origins.

And beyond that the ‘heat death of the universe’

so called “dark energy” is the cause but really no one has any idea why “dark energy” its basically just a place holder for our utter ignorance, cosmologists might as well have just said “Here Be Dragons”

Yes years ago I thought they were refereing to ‘something’, but it turns out it’s just a phrase refering to a gap in knowledge/understanding, so it could be anything, lol.

What really interesting is that the rate of expansion is increasing – so called “dark energy” is the cause but really no one has any idea why “dark energy” its basically just a place holder for our utter ignorance, cosmologists might as well have just said “Here Be Dragons”

A friend of mine described it as God Energy recently, that made me think. I’m not a believer but he may be. We got onto something that Carl Sagan said about the pattern of expansion and contraction (pre-accelerating expansion discovery). I was doing a bad job of explaining how I understood it and he just came out with that. It was before I mentioned I have a book to read about why Sagan’s understanding of cosmology was leading him towards faith rather than away from it. Is god also a placeholder for a lack of ability to understand or comprehend? I think so. But… maybe general concepts of what god is are wrong, rather the idea of there being one/it/a thing.

There was something in Cosmos (the book) that lead me to think the older image of the universe expanding was a phase and as more stars collapsed to form black holes the ratio of stars to black holes shifted, expansion slowed and eventually there was a collapse to one great singularity which would fuel the next big bang. Does accelerating expansion mean that’s not now a viable model?

 older image of the universe expanding was a phase and as more stars collapsed to form black holes the ratio of stars to black holes shifted, expansion slowed and eventually there was a collapse to one great singularity which would fuel the next big bang. Does accelerating expansion mean that’s not now a viable model?

That’s ‘the big crunch’, the exact opposite of the ‘heat death’. I certainly don’t know enough to make an informed judgement as to which is more likely but the more commonly believed theory by those who do is now the heat death.

Is god also a placeholder for a lack of ability to understand or comprehend?

Yes. In every religion ever as far as I can tell

the more commonly believed theory by those who do is now the heat death.

Seems so from a bit of reading online. Not such a nice idea overall is it : /

I tell my pupils that entropic decay explains two things. Heat death of the universe and why their rooms must be messy.

The real crazy shit starts to happen if we live in an infinite universe.

The long and short of it is, if we do, there are infinite yous, living every possible option your life could have taken, an infinite number of times, including the one we’re all living in.

I’ve always been fascinated by this too! Basically, scientists measure the age of the universe by looking at the cosmic microwave background radiation, which is like a snapshot of the universe’s early days. They analyze the patterns in this radiation to calculate how long ago the Big Bang happened. It’s kind of like looking at an old photograph and figuring out when it was taken based on the clues in the background.

I have what I hope is a sensible question that’s been in my mind for years. (I also have a second thought which I’ll put in the next post)

Einstein tells us that the concept of space time means the faster you go, the slower time gets (and the mass of a body increases) until you reach light speed, at which point time stands still. Photons, having zero mass, when travelling at light speed therefore do not experience the passing of time.

We are told that the Universe is 13.8 billion years old. Doesn’t that depend on how fast it’s going? I learned in a post above that photons didn’t exist until 300,000 years after the big bang. But surely the first ones let loose at that point will have whizzed off in a vacuum and will still be going today. If one of them happened to look down at its watch would it still read 300,000 years?

Fermilab have some excellent videos on their YouTube channel.

And another thing…

All this stuff about dark matter, dark energy. Isn’t this something that has been constructed by theoreticians to plug anomalies in the current working hypothesis of relativity and its mismatch with quantum theory?

And then there is other stuff like infinity. I’ve never got that. Divide a number by zero and you get infinity. That mucks up any sensible equation, surely. And don’t even start about multiverses. And the barmy thing I once read about (in a Roger Penrose book) that according to quantum theory it is *possible* that there is only one electron in the entire universe and it’s zipping about merrily doing the job we ascribe to the trillions of them we think we know about.

P.S. I sang Eric Idle’s Galaxy Song at a jam night last week and everybody enjoyed it!

That’s cos every interesting answer from guests and/or Cox are routinely shouted out by that halfwit Robin Ince trying to make one of his abysmal “jokes”

I’m glad it’s not just me. I find it impossible to listen to because of that smug ****, which is a shame because I like Brian Cox and the subjects covered are totally up my street.

And then there is other stuff like infinity. I’ve never got that.

Try understanding transfinity. When you do, explain it to me, please.

I don’t want to google that in case it’s all about gender politics.

All this stuff about dark matter, dark energy. Isn’t this something that has been constructed by theoreticians to plug anomalies in the current working hypothesis of relativity and its mismatch with quantum theory?

Basically, yes.

‘Dark matter’ means ‘we need more matter for this to make sense but we can’t see any more so we’ll call it dark matter until either someone finds some or comes up with a better explanation of how this works’

I tihnk (BigJohn) a lot of stuff from physics breaks down and becomes hard to comprehend as you track back towards f. ex. the Big Bang as we use the speed of light as a frame of reference as it’s so fast compared to how fast we go, that it’s effectively instantaneously fast.  Thus you get to play games with theoretical things going as fast of life being observed in two places at the same time etc .  If however you’re in a ‘Big Bang’ type of scenario when lots of particles are moving as fast as light, and are close together, a time system relative to light gets very stretched, and a heck of a lot can happen in that first few billionth of a second.

Try to imagine a concept of time relative to the speed of sound.

I’m glad it’s not just me. I find it impossible to listen to because of that smug ****

A friend organises talks* at a pub in Brighton and Robin Ince gave one last year. Much better in real life than the role he plays in infinite monkey cage and a really nice bloke. Went on to another pub with him afterwards, he has a real interest and love for science and was an interesting guy to talk to.

Lat talk was by the astronomer Richard Ellis and was about the early results from James Webb a project he was involved in, covered quite a bit on how we have refined the measurement of the distance away things are.

* Talks are organised by Brighthink and are at the Nightingale Room, Grand Central Pub just near Brighton station for any locals who might be interested. Really good range of subjects covered. I go to any I can, I’m very happy listening to anyone who knows their stuff talk about anything.

but where did the electrons/particles that caused the BB come from, what did they exist in?

A state of grace, or quite possibly total disarray! If my house is anything to go by… 🤷🏼