Brady, if you ever read this, I find your questions absolutely brilliant and asked the right way so we can understand (and i'm a french-speaker). Ed Copeland was absolutely right when he said around 11:00 "Brady, you should be here!", you truly have the curiosity and the sharpness (is it the right word?) of a brilliant scientist. Thank you for your amazing work.
Wow. Binge watching old Brady videos pays off big time. Also, the amount of understanding Brady displays in them shows he would have had the potential to be like any of his interview partners.
Ed sums up Brady's greatest gift to us all at 22:09 "Wow exactly you know how to say things scientifically correct" - I love these concepts, explained by incredible professors, through your unique questioning. Thanks Brady - never stop
I think the model of posting edited and condensed videos on the topic channels, and largely uncut footage on a secondary channel like this is a great idea. Then the people who just want the condensed version can get it, and those who want more can get this. I don't think posting largely uncut foodage like this requires much work, and if it gets 20% (or more) of the views of the main video for 10% added work (or less?) i'd say that's good value for time spent.
I just started studying Geosciences and know i know: Every time when i am feeling stressed or ask myself if all the effort is worth it i just have to watch these videos. It really is awesome to see how excited these scientists are about their work, the universe and science in general. That is the kind of scientist i want to be. tl;dr: these videos motivate me do study even more to become a better scientist.
It's a good point you make. I went to look up the estimated size of the nucleus - theory suggests a diameter of only a few light days. So at 30 light years, a quasar would have an angular size around 0.1 degrees.
Also, when people talk about the universe expanding, they mean a dilation round a point in (n+1) dimensions, like blowing up a balloon, so that everywhere on the surface gets farther from everywhere else. Because of homogeneity and isotropy, again, it can't be a simple stretch along a particular line or from a particular pole in the universe
Nothing against Brady's editing, but I agree. I realize that 20+ minute videos aren't the best for audience retention on UA-cam; but everything these guys say is a gem. So much fun to see them get excited about their field.
I have thought about this before: When you look around you might see detailed, 3d trees and buildings. Look at the horizon, you might see trees, but they are more flat/less detailed. When you look at a mountain from Earth, it is tall and jagged. When you look at it, far in space, Earth, and the mountains are flat (well, circular on the Earth) - and Earth is smooth.
2.27 I was under the impression that the radius of the observable universe is around 46 billion light years, and that means its like 92 billion light years across. Check the wikipedia article on the observable universe, under the section "misconceptions".
As someone pointed out on the other shorter video, the reference of the universe as being 13 billion light years across is off, as it's more like 93 billion light years, and that's only what the observable part of the universe is estimated to be
I second this notion. I know it might be a bit more work for Brady and the Doctors/Professors, but if they would do just a short bit and give us the name of the equation/s and a direction what to study I would be ecstatic. This and other reasons is why I don't watch the science channel anymore... well, that is if I still had cable.
I think because he's shooting from the hip: I spotted this one too: and have spotted other mistakes on other videos. I think it is very brave of them to talk to camera with no preparation as inevitably they will refer to things that may not be as fresh in their minds. I know Brady won't retake so all speech is natural: but gaffscan't be corrected, even if "doh !" 5 minutes later. I think they are marvellous in being prepared to reveal their human fallibility. Respect ! I love their vids.
I think few cosmology professors could explain this as well as is done above. Videos like this should be required watching for astronomy students. Thank you.
Except that from us to the edge of the observable universe there's a distance of about 46 billion light years. (about 93 billion light years from one side to the other).
What shapes the spatial frequency distribution of the pre-inflation field? Why can't low-frequency information be present, creating large density variations? In my experience 1/f noise is very fundamental in our universe, why is the universe apparently isotropic at any scale?
This is why we love your channels: Brady: "A big blown up projection of just a funny little wobble in a field." Expert: "Wow! Exactly! You know how to say things scientifically technically correct haha."
Now, yes. But keep in mind that they're looking "back in time" - and the universe was probably a lot smaller back then. (I might be really far off here, but that's how I understood it. I have no actual knowledge to back me up here.)
I'm subscribed to both channels. It doesn't fill up my subscription feed at all. Then again, I'm subscribed to all of Brady's major channels, so I'm interested in extra footage in general.
I have to pull Mike up on a point at about 2:30. While the universe is a bit older than 13 billion years that does not mean its 13 billion light years across. Simple reason gives you 13 point whatever billion light years in opposite directions so that is 27 billion light years across but even that does not account for co-moving distances. When they are taken into account its something over 90 billion light years across... and even that is just the observable universe, not the whole shebang.
"Entire Universe is only about 13bn light years across". Interesting quote at 2:30 I read that physicists thought the universe may be bigger or infinite, that the expansion doesn't match the speed of light and is much quicker because over millions of years we will slowly see less and less of the universe because it's expanding beyond the universe in LY to age.
Several years ago I read, about colliding branes being the cause of the "big bang", with this information I am thinking about the posibilities that the branes did not cease to exist with it.
I have a question about homogeneity: When you get to the scale when you would start to expect it, you would span quite a large part of the AGE of the universe, and since the universe is evolving, it may appear less homogeneous than it actually is.
I think that it would be really good for Brady to do a video on the statistical evidence that the writers of the paper had that implies the improbability of randomness in this structure. Not that I necessarily doubt them (I'm not honestly sure what to believe, and I'm certainly not qualified to make a definitive statement on it), but I'm personally very curious as to what it is about the structure that makes them think it's unlikely that it's the spawn of random happenstance.
EebstertheGreat Redshift of z~1.3 (the mean redshift, the real values are 1.2 < z < 1.8) means we are looking at the universe when it was around 4 billion years old, around 9 billion years to the past. I can't be arsed to check if the 1/3 of the size of the universe holds for that redshift.
I just tried a numerical calculation and z=1.3 corresponds to a time when the universe was about 26 billion light years in diameter, so he probably just meant 13 Gly in radius.
The thing which you didn't mention here, Brady, and which is crucial to understanding the homogeneity principle, is that the universe is either flat and infinite, or curved in some way, such as into a torus or sphere. It is NOT a sheet of paper, with edges, for example; if it were homogeneity obviously wouldn't be true because I could measure my distance from the edge
Not necessarily. Remember that quasars are the centers of whole galaxies. They appear point-like to us because they are so far away. If one was 30 light-years away, the brightness would be distributed over a huge area. That's not to say that it wouldn't still be a spectacular sight!
Believe it or not , I actually think that this video gave me an idea about my masters degree thesis in a completely different field - mathematical economics- ... Will look into that more, but even if it turns out that my idea cannot be applicable, I'd like to still say a HUGE "Thank you" to Brady and all the professors that appear in his videos! YOU GUYS ROCK! SCIENCE RULES !!!!!!!!!!!!!!!!
since the box filled with particles is expanding at an extrem rate, the way you understand "homogeneity" must scale with the expansion at the time it happens. the randomly created seeds or ripples for all structures carry throw this expansion. Does the mentioned paper try to date the forming of structures by reverting the timeline of there forming?
I think what he's asking is if the structure is actually a structure, or just us linking things together that aren't actually related in any way. In other words, is there a real reason for the "structure" to look the way it is, or is it purely a random scattering of particles that formed into these quasars in a way that we perceive as a pattern.
The brightest quasar can be about 4 trillion times as bright as our Sun. If a quasar was about 30 light years from Earth, it would look as bright as the Sun... imagine the havoc that would play with the seasons!
I would love if there was a channel which contained all the raw(ish) interview footage from all of your videos (across all of your channels). There is some awesome information that does not make it through editing.
Question about relativity : When we say that we're looking back through time when looking afar, is it... literal? At this point in time, do those quasars exist, or do they probably have died out and I'm just percieving them because the information simply hasn't got the time to reach me yet? Is the universe perpetually being born further and further away?
min 2:48. Why is it exactly the hypothesis that "the universe is homogeneous on a large scale" that important and where did it came from (the hypothesis)?
It can be if space expands faster than the speed of light. At points where the universe expands faster than light information cannot interact with that which it speeds away from, so it is essentially non-existant from our point of view
If the scale of homogeneity is larger than was expected does that not just imply the universe is much larger than the observable universe or has that already been factored in to the calculation?
I don't mind the 20+ videos. I'm going to Plymouth University (therefore I am stupid) and I still watch all of it (when I'm not trying to chew my chin).
From what I understand, even the observable universe is over 90 billion lightyears across due to the expansion of spacetime occuring faster than light travel. So just because the universe is 14 billion years old, doesn't mean the universe is 14 billion light years across...that seems a very silly mistake in this video...
Exactly. On top of that, the universe is about 90 billion lightyears across from every standpoint (assuming that the universe is homogeneous on large scales, which I still believe).
The current estimated diameter of the Observable Universe is about 93 billion light-years. However, the estimated age of the Universe is about 13.7 billion years. I think what we have here is just them trying to put the size of this cluster into a scale we can (sort of) understand.
How far away is this object? if we are looking "back in time" as we look farther out would you not expect to find larger objects? I find it hard to think the universe had even distribution of matter from the vary start. just a random thought
Just before inflation, let's say the universe was a centimeter sphere, wouldn't the Centre of the sphere have a very small difference of density and be ever so slightly more dense and when inflation happens and the expansion of the universe to a grapefruit takes place maybe the fluctuations or ripples it the Higgs part causes the slightly higher distribution of density that we see in the clusters of large matter in the paper?
It is said that the universe is 13.8 billion light years across at some point here. But I was under the impression it was something in the order of 90 billion? The observable universe that is. And that's because of inflation stretching spacetime out at speeds faster than light thus allowing the universe to stretch out more than it could if space couldn't move faster than light. Basically it's 90 not 14 right?
Does the Theory of Homogeneity take into account the distance that we are peering into the universe? As several comments have noted, wouldn't you expect to find large objects such as this the further out that you look? In other words, isn't everything still homogeneous at a given distance from earth, or does this structure violate that theory as well?
Ed Copeland is seriously one of my favorite people to listen to.
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Brady, if you ever read this, I find your questions absolutely brilliant and asked the right way so we can understand (and i'm a french-speaker). Ed Copeland was absolutely right when he said around 11:00 "Brady, you should be here!", you truly have the curiosity and the sharpness (is it the right word?) of a brilliant scientist.
Thank you for your amazing work.
kudos
Ed Copeland has a very relaxing voice lol
Haha yes he does and it's also adorable when he gets excited about something
Wow. Binge watching old Brady videos pays off big time.
Also, the amount of understanding Brady displays in them shows he would have had the potential to be like any of his interview partners.
Ed is awesome!
Thank you for the long version, it was quite enjoyable.
no, I just ask what is in my head... I never know what they might say so no point preparing what to ask! :)
Ed sums up Brady's greatest gift to us all at 22:09 "Wow exactly you know how to say things scientifically correct" - I love these concepts, explained by incredible professors, through your unique questioning. Thanks Brady - never stop
Ed Copeland gets excited!! Can I control myself?
Nothing like an extra helping of my two favorite Sixty Symboleers! Thanks for posting Brady!
I think the model of posting edited and condensed videos on the topic channels, and largely uncut footage on a secondary channel like this is a great idea. Then the people who just want the condensed version can get it, and those who want more can get this. I don't think posting largely uncut foodage like this requires much work, and if it gets 20% (or more) of the views of the main video for 10% added work (or less?) i'd say that's good value for time spent.
I just started studying Geosciences and know i know: Every time when i am feeling stressed or ask myself if all the effort is worth it i just have to watch these videos.
It really is awesome to see how excited these scientists are about their work, the universe and science in general. That is the kind of scientist i want to be.
tl;dr: these videos motivate me do study even more to become a better scientist.
"The ultimate elephant in the room" - now this should be a title of the paper :-D
+wiadroman but wouldnt the ultimate elephant in the room would be an elephant in a room that remains unadressed??
I'm glad you released this extended version. And I agree with Ed, you must do a thing on the inflation of the universe! :D
Thank you so much for these longer cuts! I freaking love these. Love the normal ones too but these longer ones are pretty fantastic too!
Cosmology is just the best. Thanks for posting the unedited interviews! I always watch them.
At 14:55 Ed mentions doing a video on the inflationary universe. I too would love to hear that explained, he seems really passionate about it :)
73 quasars sitting on a cosmic string, k-i-s-s-i-n-g
Noble Prize for Kibble & Copeland etal
It's a good point you make. I went to look up the estimated size of the nucleus - theory suggests a diameter of only a few light days. So at 30 light years, a quasar would have an angular size around 0.1 degrees.
Brady you've become such a pro at asking all the right questions for us. THANK YOU
Those long videos are generally good but those on astronomy/cosmology are simply awesome. Thanks Brady! :D
Mind blowing. I read the news on this couple of weeks back. Nice that it has been explained more in-depth.
I tend to watch the short version first, to get the gist of it, then the long version to go in depth.
This is even better!!!!!!! Thanks for sharing Brady!
Also, when people talk about the universe expanding, they mean a dilation round a point in (n+1) dimensions, like blowing up a balloon, so that everywhere on the surface gets farther from everywhere else. Because of homogeneity and isotropy, again, it can't be a simple stretch along a particular line or from a particular pole in the universe
I love this channel in all sorts of lovely ways.
Nothing against Brady's editing, but I agree. I realize that 20+ minute videos aren't the best for audience retention on UA-cam; but everything these guys say is a gem. So much fun to see them get excited about their field.
We need a follow up video to this. Whats the conclusion on this, or when are we likely to see one?
Has more come out to help support or debunk this?
***** How come this isnt making more of a splash in the mainstream?
Z is a ratio used to describe the redshifting of light.
simplified:
z=change in wavelength/rest wavelength
I have thought about this before:
When you look around you might see detailed, 3d trees and buildings. Look at the horizon, you might see trees, but they are more flat/less detailed.
When you look at a mountain from Earth, it is tall and jagged. When you look at it, far in space, Earth, and the mountains are flat (well, circular on the Earth) - and Earth is smooth.
I saw that I had a choice of the long version and the short version. No hesitation. I choose the long one.
2.27
I was under the impression that the radius of the observable universe is around 46 billion light years, and that means its like 92 billion light years across.
Check the wikipedia article on the observable universe, under the section "misconceptions".
As someone pointed out on the other shorter video, the reference of the universe as being 13 billion light years across is off, as it's more like 93 billion light years, and that's only what the observable part of the universe is estimated to be
For those who don't know, "z" is the term that astrophysicists use to refer to the redshift of the object they are observing.
you're welcome!
Even still, it's on the order of 46 billion light years across.
".. Okay well this is where it gets really fun", oh Ed, your entire explanation was fun!
I second this notion. I know it might be a bit more work for Brady and the Doctors/Professors, but if they would do just a short bit and give us the name of the equation/s and a direction what to study I would be ecstatic.
This and other reasons is why I don't watch the science channel anymore... well, that is if I still had cable.
I think because he's shooting from the hip: I spotted this one too: and have spotted other mistakes on other videos. I think it is very brave of them to talk to camera with no preparation as inevitably they will refer to things that may not be as fresh in their minds. I know Brady won't retake so all speech is natural: but gaffscan't be corrected, even if "doh !" 5 minutes later. I think they are marvellous in being prepared to reveal their human fallibility. Respect ! I love their vids.
That wow at the end was awesome
I agree with @JamesMulvale. You're the most science content guy in the group of famous science content creators right now. Kudos!
I think few cosmology professors could explain this as well as is done above. Videos like this should be required watching for astronomy students. Thank you.
Except that from us to the edge of the observable universe there's a distance of about 46 billion light years. (about 93 billion light years from one side to the other).
22 minute extended footage video... Just what I like to see :)
What shapes the spatial frequency distribution of the pre-inflation field? Why can't low-frequency information be present, creating large density variations? In my experience 1/f noise is very fundamental in our universe, why is the universe apparently isotropic at any scale?
This is why we love your channels:
Brady: "A big blown up projection of just a funny little wobble in a field."
Expert: "Wow! Exactly! You know how to say things scientifically technically correct haha."
I'm very sure at one point Brady is going to receive an honorary doctorate from Nottingham University.
I wish you linked to these videos at the beginning Brady, half the video I already watched.
Ed is a lovable guy.
Now, yes. But keep in mind that they're looking "back in time" - and the universe was probably a lot smaller back then. (I might be really far off here, but that's how I understood it. I have no actual knowledge to back me up here.)
I'm subscribed to both channels. It doesn't fill up my subscription feed at all. Then again, I'm subscribed to all of Brady's major channels, so I'm interested in extra footage in general.
I have to pull Mike up on a point at about 2:30.
While the universe is a bit older than 13 billion years that does not mean its 13 billion light years across. Simple reason gives you 13 point whatever billion light years in opposite directions so that is 27 billion light years across but even that does not account for co-moving distances. When they are taken into account its something over 90 billion light years across... and even that is just the observable universe, not the whole shebang.
Not sure if equations work for this particular video very well but I would be interested in peeking into the math behind the papers most definitely
Thank you, Brady for today's videos :)
"Entire Universe is only about 13bn light years across". Interesting quote at 2:30
I read that physicists thought the universe may be bigger or infinite, that the expansion doesn't match the speed of light and is much quicker because over millions of years we will slowly see less and less of the universe because it's expanding beyond the universe in LY to age.
Wow -- there's something to think about, thanks Brady.
Several years ago I read, about colliding branes being the cause of the "big bang", with this information I am thinking about the posibilities that the branes did not cease to exist with it.
08:30 elicits an answer showcasing what is so great about the scientific method.
So beautiful! Thank you
More extended interviews!
Now I get it the small fluctuations in the uniform field are caused by star fish
I have a question about homogeneity: When you get to the scale when you would start to expect it, you would span quite a large part of the AGE of the universe, and since the universe is evolving, it may appear less homogeneous than it actually is.
I think that it would be really good for Brady to do a video on the statistical evidence that the writers of the paper had that implies the improbability of randomness in this structure. Not that I necessarily doubt them (I'm not honestly sure what to believe, and I'm certainly not qualified to make a definitive statement on it), but I'm personally very curious as to what it is about the structure that makes them think it's unlikely that it's the spawn of random happenstance.
The universe is much bigger than Mike realizes. It is not 13 billion light years in diameter but rather 93 billion light years.
EebstertheGreat Redshift of z~1.3 (the mean redshift, the real values are 1.2 < z < 1.8) means we are looking at the universe when it was around 4 billion years old, around 9 billion years to the past. I can't be arsed to check if the 1/3 of the size of the universe holds for that redshift.
Matti Kauppinen Well he said 13 billion light years _in diameter_, which would make it off by a factor of 7. I think he just misspoke, maybe.
EebstertheGreat Yeah, I'm not sure either^^
I just tried a numerical calculation and z=1.3 corresponds to a time when the universe was about 26 billion light years in diameter, so he probably just meant 13 Gly in radius.
The thing which you didn't mention here, Brady, and which is crucial to understanding the homogeneity principle, is that the universe is either flat and infinite, or curved in some way, such as into a torus or sphere. It is NOT a sheet of paper, with edges, for example; if it were homogeneity obviously wouldn't be true because I could measure my distance from the edge
Not necessarily. Remember that quasars are the centers of whole galaxies. They appear point-like to us because they are so far away. If one was 30 light-years away, the brightness would be distributed over a huge area.
That's not to say that it wouldn't still be a spectacular sight!
Believe it or not , I actually think that this video gave me an idea about my masters degree thesis in a completely different field - mathematical economics- ... Will look into that more, but even if it turns out that my idea cannot be applicable, I'd like to still say a HUGE "Thank you" to Brady and all the professors that appear in his videos!
YOU GUYS ROCK!
SCIENCE RULES !!!!!!!!!!!!!!!!
since the box filled with particles is expanding at an extrem rate, the way you understand "homogeneity" must scale with the expansion at the time it happens. the randomly created seeds or ripples for all structures carry throw this expansion. Does the mentioned paper try to date the forming of structures by reverting the timeline of there forming?
I think what he's asking is if the structure is actually a structure, or just us linking things together that aren't actually related in any way. In other words, is there a real reason for the "structure" to look the way it is, or is it purely a random scattering of particles that formed into these quasars in a way that we perceive as a pattern.
The brightest quasar can be about 4 trillion times as bright as our Sun. If a quasar was about 30 light years from Earth, it would look as bright as the Sun... imagine the havoc that would play with the seasons!
I would love if there was a channel which contained all the raw(ish) interview footage from all of your videos (across all of your channels). There is some awesome information that does not make it through editing.
Could there be pockets of small bits of matter packed together from the force of larger bits around them?
All praise be to Dave!
Oh my god yes please yes we need to see this happen!!
Question about relativity :
When we say that we're looking back through time when looking afar, is it... literal? At this point in time, do those quasars exist, or do they probably have died out and I'm just percieving them because the information simply hasn't got the time to reach me yet? Is the universe perpetually being born further and further away?
min 2:48. Why is it exactly the hypothesis that "the universe is homogeneous on a large scale" that important and where did it came from (the hypothesis)?
You should check out www.physicsforums.com/ and ask this question there. The community is great and all about helping learn and understand new things.
the more physicists delve into these matters the more I think that nothing is random in the universe.
I thought the universe was 92 billion lights years across but 13.8 billion years old ?
It can be if space expands faster than the speed of light. At points where the universe expands faster than light information cannot interact with that which it speeds away from, so it is essentially non-existant from our point of view
If the scale of homogeneity is larger than was expected does that not just imply the universe is much larger than the observable universe or has that already been factored in to the calculation?
I don't mind the 20+ videos. I'm going to Plymouth University (therefore I am stupid) and I still watch all of it (when I'm not trying to chew my chin).
They probably used poisson distribution, to estimate the probability of the structure arising randomly.
it ejects radiation, which is a part of the spectrum of light, just not the part we can see. it's an animation.
I like how this titel is more scientific (structure) but the one on the "mainstream" channel is more vague.
Still good content.
You should totally put some background music to these interviews. A little ambiance would make them a little better, I think.
am getting to excited... i have to slow down...lol
From what I understand, even the observable universe is over 90 billion lightyears across due to the expansion of spacetime occuring faster than light travel. So just because the universe is 14 billion years old, doesn't mean the universe is 14 billion light years across...that seems a very silly mistake in this video...
I thought the same thing. Maybe a little brain lapse in Merrifield. He’s the man so he’s instantly forgiven in my book
Exactly. On top of that, the universe is about 90 billion lightyears across from every standpoint (assuming that the universe is homogeneous on large scales, which I still believe).
I was reading a paper on black holes today and I kept seeing the variable z and here I see it as well. what does z reference in astrophysics?
The current estimated diameter of the Observable Universe is about 93 billion light-years. However, the estimated age of the Universe is about 13.7 billion years.
I think what we have here is just them trying to put the size of this cluster into a scale we can (sort of) understand.
Do you prepare your questions beforehand brady, because you really ask good questions?
How far away is this object? if we are looking "back in time" as we look farther out would you not expect to find larger objects? I find it hard to think the universe had even distribution of matter from the vary start. just a random thought
Just before inflation, let's say the universe was a centimeter sphere, wouldn't the Centre of the sphere have a very small difference of density and be ever so slightly more dense and when inflation happens and the expansion of the universe to a grapefruit takes place maybe the fluctuations or ripples it the Higgs part causes the slightly higher distribution of density that we see in the clusters of large matter in the paper?
It is said that the universe is 13.8 billion light years across at some point here. But I was under the impression it was something in the order of 90 billion? The observable universe that is. And that's because of inflation stretching spacetime out at speeds faster than light thus allowing the universe to stretch out more than it could if space couldn't move faster than light. Basically it's 90 not 14 right?
'z' refers to the red shift, z = Δλ/λ
If John Archibald Wheeler were still alive, he would be laughing his arse off at this discovery.
I wondered about that. He must surely know this, so I wondered if it had some other significance.
Quasars being the nuclei of galaxies, if they've formed such a structure, does it mean the galaxies have formed a cluster?
Does the Theory of Homogeneity take into account the distance that we are peering into the universe? As several comments have noted, wouldn't you expect to find large objects such as this the further out that you look? In other words, isn't everything still homogeneous at a given distance from earth, or does this structure violate that theory as well?
Why can't you post this on your main channel? I enjoy seeing the whole thing.
i must say i prefer the longer videos.