Big bang question. Any physics major here?

[mervyn]

Two of my grandchildren and I were looking at deep space pictures via Hubble over the week-end. One of their questions had me stumped. Having explained to them that the Big Bang occurred nearly 15 billion years ago, we then looked at a picture showing the universe ‘shortly after the big bang’. Their question was ‘how can we see an image nearly 15 billion years old, if we ourselves are nearly 15 billion years away in time (at a speed much slower than the speed of light) since that event?’. Can anyone give me an answer?

 

[The Unseen Green]

Whilst certainly no expert, this is my limited understanding.
I believe a single blade of grass could help to explain.

If one were to use an optical aid to focus on a single blade of grass a couple of miles away, you would see it's movement in the wind, but not one movement will be seen by you in the exact instant it's happened - purely because of light.

Light is subject to waves - hence the distortion you see when vapour or high temperatures are present. That distortion isn't just the overtly visual, it also impacts the inherent behaviour of light travel.

The movement of that blade of grass is visually fed to your eyes via light but, irrespective of what optical device you use, the very instant of that movement passed before you witnessed it.

Light itself must travel within the field of quantum mechanics - a broader concept that does certainly require a proper brain to explain. The further away something is, the more the light which conveys the visual impression is subject to conditional distortion.

In QM, there is the concept of Wave-Particle Duality.
When you witness something in close proximity, you see the particle observation - the tip of your finger for example. Particle observation has natural waves, but they're so slight that you won't be aware of them while looking at your digit.
When you view something that occurred billions of years ago, you see an observation of a particle event that has been influenced by other particle impressions and their respective waves - thus creating waves of light distortion that would impact the visual impression were it not for the artificial optical mechanisms at play via the genius technology on board Hubble.

The one thing about the Big Bang that puzzles some is the reality that we can actually witness events that are even older than the Big Bang, but this is simply because the sum amount of respective conditional distortion of light is lesser to the extent that the visual impression can be received by us sooner.

Again, certainly no expert, but I do find this stuff fascinating and, as I'm sure I'm probably wrong somewhere in all of that, I would also like an expert to explain.

 

[MickyD]

Inflation - of space itself, which, unlike light in space, can travel at any 'speed' it likes.

The observable universe is a sphere with Earth at its centre (just because it's the centre of our viewpoint, not because the Earth is the centre of anything at all) that's currently about 93 billion lightyears in diameter. That seems counterintuitive given the age of the universe and the speed of light in a vacuum, but Inflation Theory is currently an excellent model for what we observe.

Space, especially in the first unimaginably brief moments following the Big Bang, has travelled way, way faster than light ever could. There are many excellent YouTube videos on the vast and bizarre related subjects of cosmology and cosmogony for those interested in learning more. Like quantum physics, it's a very deep rabbit hole!

Cue the young-Earth creationists and space-denying flerfs...

 

[Steamer]

My mate Prof Brian said in his recent lecture tour that we can only see what we can see, 14.5 billion light years which suggests that our observable universe is some 29 billion light years from side to side. He says that the whole universe might be somewhat bigger and that it is probably flat. So imaging you have a balloon (the whole universe) and draw a little circle on it, this little circle is out observable universe, the bit we can see, now blow the balloon up (inflation/big bang) and our observable universe gets bigger and bigger but so does the whole universe i.e. the balloon. Our observable universe is a relatively small disc on the outer edge of the whole universe. It is essentially flat. This leaves the idea that there is a tremendously large amount of universe out there (the rest of the balloon) which we cannot see. The rest of the universe may be billions of times larger than the observable universe with trillions and trillions of galaxies ... pretty amazing, as it all originated from a singularity. This leads to the thought that the big bang/inflation may still be going on, hence the ever increasing size of the universe but one day may contract or maybe a new singularity may form.

Prof Brian went on to say that there is a famous observable universe map (its coloured blue and red and relates to subtleties of temperature differences) The subtle temperature differences resulted in the young universe gasses condensing more in one area of the universe than another (it may have been that the act of condensing cooled one area of the universe from another) and this condensation led to the galaxies' and galaxy groups. Prof Brian also said that if these temperature subtleties were more varied in another part of the whole galaxy (another part of the balloon), then the laws of physics, as we know them, may be strangely different.

If you get a chance to go to Prof Brian's travelling lecture tour, it is well worth it. You may forget everything he says by the time you get home but strangely, you understand it all as he explains it in his lecture.

Of course, this is all theory and needs to be tested and tested but I would happily put my pound on this being essentially true ... maybe someone has another theory which trumps Prof Brian's

 

[Andy S]

Sadly…I am addicted to all this stuff. Cox, de Grasse Tyson, the Japanese fella, Brian May bring it all on. You Tube is the bestest thing since Einstein’s Theory of Relativity.

 

[Mat]

IYKYK

 

[Butternubs]

Brian Greene's Fabric of the Cosmos is a great read that explains just about everything about sub-atomic particles, the universe and light speed. its fab.

 

[mervyn]

Inflation - of space itself, which, unlike light in space, can travel at any 'speed' it likes.

The observable universe is a sphere with Earth at its centre (just because it's the centre of our viewpoint, not because the Earth is the centre of anything at all) that's currently about 93 billion lightyears in diameter. That seems counterintuitive given the age of the universe and the speed of light in a vacuum, but Inflation Theory is currently an excellent model for what we observe.

Space, especially in the first unimaginably brief moments following the Big Bang, has travelled way, way faster than light ever could. There are many excellent YouTube videos on the vast and bizarre related subjects of cosmology and cosmogony for those interested in learning more. Like quantum physics, it's a very deep rabbit hole!

Cue the young-Earth creationists and space-denying flerfs...

You’ve really had me pondering here MickyD. Whilst being aware that our universe is expanding, I’d not realised it was expanding faster than the speed of light. Because of speed of light limitations and an expanding universe I’d always assumed future space travel beyond our solar system would be forever impossible, until/unless suspended animation was developed, as in sci-fi films. I now wonder if whatever the force is that’s expanding the universe (is this dark energy?) could this in some future way be harnessed to make faster than light travel possible. All mind boggling stuff.

 

[MickyD]

You’ve really had me pondering here MickyD. Whilst being aware that our universe is expanding, I’d not realised it was expanding faster than the speed of light. Because of speed of light limitations and an expanding universe I’d always assumed future space travel beyond our solar system would be forever impossible, until/unless suspended animation was developed, as in sci-fi films. I now wonder if whatever the force is that’s expanding the universe (is this dark energy?) could this in some future way be harnessed to make faster than light travel possible. All mind boggling stuff.

Welllll... faster than light (FTL) travel, or even travel anywhere near c (the speed of light) does seem a genuine impossibility for anything that has mass. (Photons - light itself - have no mass so that's why they travel "at the speed of light".)

Einstein's General Relativity (GR) is incredibly successful as a model, and has been shown to be extremely accurate countless times over the decades through observations of phenomena that it predicted; and GR states unequivocally that it would take infinite energy to accelerate a mass up to the speed of light. (Even things like GPS only work because tiny timing adjustments have to be made to account for the fact that the satellites are travelling ever so slightly faster relative to the Earth, and that's just one of numerous examples of GR in action.)

That said, it's known that GR is not the final answer - for instance, it predicts black holes but it can't describe what happens inside them, a singularity basically representing an inability of equations to describe something perfectly down to the finest detail. If you ever get something that looks like infinite density or infinite anything, you know something's not quite right. Sooner or later, we're going to have to come up with a theory that marries gravity with the other three fundamental forces, all of which are happily described in quantum terms. Try as they might, though, scientists still haven't cracked that one. (Maybe it's 42?)

GR is just that much more refined and accurate than the Newtonian gravity theory that preceded it, but it does seem that it really would take something like the warping of spacetime to kind of cheat c. There's been much talk in recent years about the Alcubierre drive but that would take unimaginably huge amounts of negative energy, which as far as we know doesn't even exist.

But yes, that negative energy just might be associated with... drum roll... dark energy. So who knows?! Maybe Star Trek's warp drives are Alcubierre drives.

 

[cheshiregreen]

BBC News - Earliest and most distant galaxy ever observed

James Webb: Earliest and most distant galaxy ever observed

The James Webb Space Telescope smashes its own record for detecting the most distant known galaxy.

www.bbc.com

 

[Daz]

If people would like to get in to emotive discussions about god/creationsim they are welcome to do so on other forums away from Pasoti. This thread or forum isn't the place for those types of discussions.

 

[Butternubs]

There is also time and correspondence theory that states that any point in the universe is actually only an atom width apart from each other. The idea runs that if you have a sheet of A4 paper and put a dot at each corner, then fold the paper back on itself corner to corner so the corners with the dots are touching each other, you can see that if you travel across the plane of the paper, the dots remain 30cm apart, but they are also millimetres apart due to the bend in the paper, if you travel through the paper. This theory is often cited in relation to wormholes, which some believe are the avenues between these direct points. FTL travel then becomes irrelvant if you can find a way to effectively 'fold' space.

 

[Ave IT]

Not sure how I missed this thread ...... I too love this stuff, and although I'm a Physics grad from many moons ago wouldn't pretend to be an expert - although to be fair I don't think anybody really is an 'expert', it's just the likes of Brian Cox et al who know more than the rest of us mortals.

Anyway, here are a couple of very good links below that are really quite digestible whether you have any science background or not and will certainly help with Mervyn's original question.

It is indeed all about accounting for the expansion of space itself (General Relativity) as well as how fast things are moving thru' it (Special Relativity). A couple of the posts above question how fast space itself is expanding ..... but as the links both show that depends where/what you are looking at (ie how far the object is away from us). The more distant it is the faster it is receding to the point where it is effectively moving faster than the speed of light from us in terms of 'special relativity' .... even though it's not really. (Read the links to get that explained far more clearly).

To add to the complication (although not mentioned in these links) both time and space are inter-twined and given that we define 'speed' as the distance moved (thru' a space) in a particular time period then things get very blurred indeed.

Something that freaks me out is that this isn't just some weird abstract theory but something we have to accommodate with our SatNav systems and something I work with simulating our satellite signals. Basically the time that passes for our GPS satellites (other systems are available) which are about 12,000 miles from Earth is quite different to the time that passes for us here on Earth. In other words the clocks on the satellites run at a quite different rate to identical clocks on Earth. Just think about that for a bit ..... How mind-bending is that? It challenges our human perception of time if it flows differently depending where you are and how fast you are moving thru' space!!

If it wasn't for a certain very clever chap by the name of Einstein who figured this out way before satellites were launched and gave us equations to work out precisely the offsets that need to be accounted for then we'd never have SatNav systems to direct huge lorries down narrow country lanes. However, that difference in time for Earth and the satellites is not to do with expansion of space but the effect of gravity - or more precisely the way the mass of the Earth distorts the space-time around us. Those photos from Hubble and the JWST that show galaxy clusters allow us to actually see how space (and time) can be warped by large objects. It's quite bizarre - it means more distant galaxies beyond the cluster appear as if we are viewing them thru' a lens appearing magnified and on either edge. How freaky is that? Space-time itself bending! But bending into what?? ...... Time for a lie down methinks .

https://www.skyatnightmagazine.com/space-science/does-universe-expand-faster-than-light

How Come Cosmic Inflation Doesn't Break The Speed Of Light?

If it can stretch the Universe from the size of a subatomic particle to billions of light years in a fraction of a second, why doesn't Einstein's relativity forbid it?

www.forbes.com

 

[GreenThing]

Not sure how I missed this thread ...... I too love this stuff, and although I'm a Physics grad from many moons ago wouldn't pretend to be an expert - although to be fair I don't think anybody really is an 'expert', it's just the likes of Brian Cox et al who know more than the rest of us mortals.

Anyway, here are a couple of very good links below that are really quite digestible whether you have any science background or not and will certainly help with Mervyn's original question.

It is indeed all about accounting for the expansion of space itself (General Relativity) as well as how fast things are moving thru' it (Special Relativity). A couple of the posts above question how fast space itself is expanding ..... but as the links both show that depends where/what you are looking at (ie how far the object is away from us). The more distant it is the faster it is receding to the point where it is effectively moving faster than the speed of light from us in terms of 'special relativity' .... even though it's not really. (Read the links to get that explained far more clearly).

To add to the complication (although not mentioned in these links) both time and space are inter-twined and given that we define 'speed' as the distance moved (thru' a space) in a particular time period then things get very blurred indeed.

Something that freaks me out is that this isn't just some weird abstract theory but something we have to accommodate with our SatNav systems and something I work with simulating our satellite signals. Basically the time that passes for our GPS satellites (other systems are available) which are about 12,000 miles from Earth is quite different to the time that passes for us here on Earth. In other words the clocks on the satellites run at a quite different rate to identical clocks on Earth. Just think about that for a bit ..... How mind-bending is that? It challenges our human perception of time if it flows differently depending where you are and how fast you are moving thru' space!!

If it wasn't for a certain very clever chap by the name of Einstein who figured this out way before satellites were launched and gave us equations to work out precisely the offsets that need to be accounted for then we'd never have SatNav systems to direct huge lorries down narrow country lanes. However, that difference in time for Earth and the satellites is not to do with expansion of space but the effect of gravity - or more precisely the way the mass of the Earth distorts the space-time around us. Those photos from Hubble and the JWST that show galaxy clusters allow us to actually see how space (and time) can be warped by large objects. It's quite bizarre - it means more distant galaxies beyond the cluster appear as if we are viewing them thru' a lens appearing magnified and on either edge. How freaky is that? Space-time itself bending! But bending into what?? ...... Time for a lie down methinks .

https://www.skyatnightmagazine.com/space-science/does-universe-expand-faster-than-light

How Come Cosmic Inflation Doesn't Break The Speed Of Light?

If it can stretch the Universe from the size of a subatomic particle to billions of light years in a fraction of a second, why doesn't Einstein's relativity forbid it?

www.forbes.com

Interesting about the time difference depending upon speed. It’s been said that someone who goes to live up a mountain will experience time slightly slower than someone who is living at sea level as they are travelling through space faster. This is experience by everyone to some extent but not noticeable as the differences are minuscule. I’ve wondered if that is what produces the phenomenon of Deja vu. Maybe you feel like you’ve experienced something before because you actually have, albeit a fraction of a second before.

 

[Quinny]

Interesting about the time difference depending upon speed. It’s been said that someone who goes to live up a mountain will experience time slightly slower than someone who is living at sea level as they are travelling through space faster. This is experience by everyone to some extent but not noticeable as the differences are minuscule. I’ve wondered if that is what produces the phenomenon of Deja vu. Maybe you feel like you’ve experienced something before because you actually have, albeit a fraction of a second before.

It's a bit more complex than that (obviously). In terms of the mountain analogy it's the other way around: that you travel faster the further away from the source of gravity you are, so a clock at the top of a mountain will go faster than a clock at sea level. But the difference is so slight you wouldn't notice it: the difference is something like 10 nanoseconds a day different per km above sea level. So we're in atomic clock territory to measure that kind of difference. So if there was a hypothetical clock at the altitude of the summit of Everest (8,800metre above sea level) since the formation of the Earth 4.5 billion years ago, that clock would right now be just over 30 minutes faster than another hypothetical clock at sea level.

However, if you gave an astronaut in orbit above the Earth's atmosphere (such as those on the International Space Station) a clock, what you see there is that their clock will go slower than the hypothetical one at sea level: this is because the astronaut's relative velocity to the clock at sea level is greater, and greater velocity = slower time (for them, being in effect perpetual "free-fall" around the Earth, velocity is a bigger factor than gravity). So you could have a hypothetical scenario of three astronauts with a clock: one is launched into space to the ISS, one climbs a mountain to watch the launch, and the third stays at Cape Canaveral. The one on the mountain ages quicker than the one at the space centre in Florida, but they both age quicker than the one up in the ISS.