When galaxies were born - with Richard Ellis
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- Опубліковано 10 тра 2023
- Join Richard Ellis as he discusses his spectacular discoveries in modern cosmology over the last 40 years.
Watch the Q&A here: • Q&A: When galaxies wer...
Read Richard's book here: geni.us/uBe2lf
Astronomers are like time travellers. They scan the night sky for the outermost galaxies that first came into being when our universe was a mere fraction of its present age.
In this talk, discover how a pioneering generation of scientists can now witness the time when starlight first bathed the cosmos and galaxies emerged from darkness.
This talk was recorded at the Ri on 27 March 2023.
Richard Ellis is Professor of Astrophysics at UCL. During his career his research has moved from detailed studies of nearby stars, topics in Galactic structure and nearby galaxies to broader questions relating to the large scale structure of the Universe and its contents, and the formation and evolution of galaxies. His recent work addresses the origin of the earliest galaxies and understanding their role in cosmic reionisation.
His programmes are primarily observational exploiting ESO’s Very Large Telescope, the twin Keck telescopes and the Atacama Large Millimetre Array (ALMA). He remains enthusiastic about the use of new instruments and observational opportunities when they further the progress that can be made in these areas. He is co-scientific lead for the Prime Focus Spectrograph, a highly- multiplexed instrument for the Subaru 8 metre telescope in Hawaii, and looking forward to the progress of the NASA James Webb Space Telescope.
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Richard Ellis is a great contributor to the theory of cosmology. It is a pleasure to hear him speak plainly and clearly for a general audience on a deep subject of which he is a master.
In this Space Time, to be a human seems absolutely wonderous, is absolutely grand.
The best explanation of the expansion of the universe I've heard. The best introduction to the recent history of observational astronomy and the most optimistic assessment of what we hope to achieve with JWST
Dear RI, when the presenter points something on screen, please try to capture it on camera (or with a virtual pointer).
Thanks, and keep up the good work!
Great lecture, love when stuff like this gets presented so well. Many thanks
great lecture so interesting so much better than the television
11:16 and now JWST is contradicting this notion, because it discovered galaxies at high Z that are big (on the scale of Milky Way) and well developed. So basically we have to revisit our theories of galaxy evolution.
Well, it would have been exciting if that were true. Unfortunately, it looks like it wasn't. Stars are groups of sizes and brilliance, and the small ones are relatively heavier than the big ones. So we took an average from our Milky Way today (the IMF) and applied it to other galaxies 13 Billion years ago when the Universe was much hotter and denser. We then measured the total _light output_ and from that, and inferred size. But we compared it to our local average today in a cooler expanding universe, and got the predictably wrong answer.
So basically, galaxies were brighter back then because they had more big stars and fewer little ones.
We did learn something: you can't apply our galaxy today to every other galaxy in the Universe across 13 Billion years.
@@onebylandtwoifbysearunifby5475 someone watched Dr Becky;).
@@oskarskalski2982 I do like Dr. Becky, she does a good job. That particular one came from Charlie Conroy's study of IMF at the Keck telescope (also a good read). It looks like velocity and shape (like elliptical) are big factors effecting the universal (not so universal) mass function of galaxies. So i suspected IMF could be off for these earliest galaxies just due to that (velocity and irregular shapes), but Dr. Becky did a better job explaining it. The background temperature makes good sense, as 40 deg K is a fair bit different than 2.7 K. Volume of stars increasing with the cube of size, while surface area only increasing with the square of size, makes luminosity measurements rather dubious when inferring mass. There's much more fusion going on as stars get bigger. So brightness measurements for mass is kind of a moving target.
Like all new exciting pre- discoveries, it's usually good to keep the cork on the champaign just a bit longer, just in case.
Good to see you're up on events, most people i talk to start asking me what the International Monetary Fund has to do with galaxy size. ;)
@@onebylandtwoifbysearunifby5475 haha, I doubt that most people I talk to could even attribute IMF to International Monetary Fund:). I love all things connected to astrophysics and physics in general so I try to be up-to-date on this topic. And Dr. Becky immediately came to my mind because she explained it in one of the recent videos but she used Paul Steinhard's work, at least that's what she presented as the data on which the whole premise is based.
There is so much we don't know about the early universe and its great to be around the time when JWST is making it's discoveries. I hope I will live long enough to witness telescope using solar gravitational lense to observe exoplanets. There are plans for it but it is years in making.
@@oskarskalski2982 Yes, Solar Diver solar sails! That would be very exciting to actually see the surface of an exoplanet in optical astronomy. Gravitational telescopes would be fantastic, provided there's some leftover money after the military budget... Sigh. But what a good time to live, when both Hubble and JWST and VLT and ELT are coming online. The idea of actually _seeing_ the early Universe is still one I'm trying to fully grasp. It's like a Sci-Fi movie... Just amazing.
Gandalf gave a good lecture here. Well above average, with enough specific detail to keep even seasoned people interested.
Haven't found anything specific or new except details of his biography. There is problems and paradoxes with every techniques and tools he told about up to our current cosmological model of early universe - and that's the most interesting thing. That lack of what he called 'pure hydrogen' galaxies and abundance of those with quite heavier elements in supposedly overpopulated early universe - is one indicator.
Gandalf 🤣🤣🤣
Great lecture, enjoyed a lot!
Very excellent and informative presentation. Thank you thank you.
Enjoyed it! Thank you.
Thank you! Cheers.
Brilliant speaker!
Awesome chat :)
fascinating
Amazing
From James Burke Magnus Pike Star Trek Arthur c Clarke Douglas Adams Ray Bradbury ... explained satuan rocket till present day methods of
propulsion the shared graphics from various sources
Really awesome watch ISS flyby many times .. thankyou les for being so informative ...
We currently believe in 3 generations of "Star Formations" that make up our Universe, and each gets "heavier" with new elements. Perhaps a 4th is needed. Short lived "Proto-Stars" between the end of expansion the other generation of Stars and their clustering traits. Again, Gravity will be important. Are they just dense hot gas clouds?
layman's Q:
Re: 'cosmic dawn' 13:37 clouds of H gas collapsing... eventually into stars:
which came first; mass (as given through the Higgs field ?) or gravity ?
seems to this layman as though gravity effectively doesn't exist until and unless mass exists, yet gravity is required to coalesce matter into ever more dense and more MASSive objects.
Thanks for any feedback/links to high school level explainers.
The Higgs mechanism contributes only a small fraction to the origin of mass. A good explanation of this can be found in a Ri talk given by Jim Baggott on 'the concept of mass' here on UA-cam.
gravity was first. And gravity doesn't just couple to mass, it couples to stress energy (mass, energy, energy flux, momentum change, stress and pressure)...c.f the other comment about proton mass being mostly not from quark mass--however, that extra stuff really isnt mass, it's energy holding the quarks together ,but it's not binding energy, since binding energy is negative...it's just the energy of QCD existing (which is the most impossible thing to understand quantitatively).
This could be a somewhat dumb question, but here goes.
When we make observations of galaxies near 12 billion light years away, how are we determining their size/mass? I understand the approximation of distance via the Doppler effect and spectral/variable star analysis. But I can't quite put my finger on how we determine the size or mass of these far off galaxies. Yet we hear the declarative "they are much smaller" more than a couple times.
Most likely by their luminosity. We assume that galaxies have an average brightness due to their mixture of star types so we measure the brightness of these galaxies compared to galaxies we do know the mass of.
@@borisjohnson1944 That's fair, but I'm sure the problem of making many assumptions based on luminosity are somewhat apparent. And despite being interested in cosmology and a lot of the various inferences we can make to estimate numerous values for the properties of these objects, I still feel that much of our information is based on assumptions that can't plainly be measured directly.
That's not to discount any of the work being done by any means. Even when I look towards a lot of the mathematics behind the research, I just find myself blown away by how much we have been able to figure out. But my issue arises more from the degree of certainty that is often associated with these observations and calculations. Much of it is built up on assumed premises and inferred data, despite the admission that our models are very much so incomplete. I think that there are degrees of certainty within the field that are often overstated and oversimplified when disseminating information to the public at large. Like the way the Ultramassive Black Holes (or S.L.A.B.s) are very often overestimated to gain media attention while research is either outdated or unsure.
Even when you calculate the various redshift values for galaxies at a certain distance, your measurements can vary wildly depending on the data set and your bias to weigh them against one another. All it takes to massively skew the measurement is a tiny deviation in the spectral analysis, visibility of matter, and especially all of the instruments and conditions of observations. We also don't know what we don't know. The whole premise for things like "Dark Matter" and "Dark Energy" arose from observations that were inconsistent with expectations from our theoretical models. We simply don't know what confounding variables might exist, let alone how to account for them to ensure we give accurate properties and quantities during analysis.
Since distance is one of the most difficult properties to determine, and is fundamental to pin down other attributes, I find it difficult to accept a lot of the declarations made about objects where specific values are assigned based upon the presumed distance. I think most people should consider everything with the disclaimer that we are presenting a "best guess" that could be varied quite a bit from what we currently estimate based on things we are currently unaware of.
Using “standard candles” Like cepheid variables. Although they shrink a little they are pretty uniform in size and brightness, therefore can be used in some cases to compare. These only tend to work with “closer objects” but we can use them to calibrate the next “rung on the ladder”. Look up the “extragalactic distance ladder” and “standard rulers” and “Baryon acoustic oscillations” and you can see how this is a topic that has been thoroughly covered, and IS very important.
It’s no dumb question.
@@drewishaf And saying we “don’t know everything” should never prevent anyone from sharing the wealth of data we do know, as the entire pursuit and purpose of science is to reshape that knowledge with something that works better.
I've seen other lectures that say the opposite. The galaxies were very large. Much larger than anyone expected. That was just days ago .
Does this mean that space has expanded quicker than the light from those early galaxies?
I'm watching this in Launceston, and even I'm not sure Tasmania exists.
The power of a telescope is roughly proportional to the square of the radius of the primary mirror.
I think the gravity at L2 from the earth and the sun is greater than the gravity from the sun at the earth because the centrifugal force at L2 is larger....however, if you believe in the equivalence principle, then you can lump centrifugal (and Coriolis) force in with gravitation...recovering the original statement.
Is this the same area of space seen from hubble ultra deep 2012?
51:15 Earth: MG/R^2=ω^2R; JWST: MG/(R+r)^2=ω^2(R+r)
(M and m are mass of Sun and Earth resp, R is 1AU, r is distance to JWST)
Setting α=r/R these combine to 3α^3+3α^4+α^5=(m/M)(1+2α+α^2).
In good approximation this gives α=(m/3M)^(1/3)=1%.
I can’t watch this because the google adverts are too loud.
i want more from the Royal Institution.
How can space itself be expanding, when space is not a material entity?
Is his analysis outdated because of JWT?
When galaxies were born, I was very young.
We pretty much know how things evolved after the singularity, but will we ever know it's origin?
Probably the creation of the black hole we exist within. Also, the universe doesn't expand outwards, but inwards, as we are speeding up towards the never reachable center.
I wonder if this scenario could add up with what we know. I'm just an armchair mastermind, so i don't know anything lol
the universe isn't expanding in any direction, in fact whats happening is the fabric of spacetime within it is whats expanding, in all directions at once, you could say, but wouldnt exactly be accurate either. @@awebmate
a milimeter is still a milimeter, there is just more and more of them
@@clown134 a millimeter is always a millimeter, just like a second is always a second. It depends on the observer. Due to relativity it is impossible to tell the difference between expanding inwards or outwards.
Hes talking about a bunch of stuff we already heard
Why is the audio in this video nearly inaudible? Whoever is in charge of exporting videos for UA-cam at the RI needs to figure out the proper audio settings. This is an amateur mistake.
Space X has changed the cost, efficiency of space flight & the same will happen with scientific projects in the near future now NASA doesn't hold a monopoly on it & could drag its feet. 25 years is ridiculous time frame from start to finish & I suppose dragging it out keeps the wages rolling in. No disrespect to you though, Im talking in general terms, Great video, thanks.
I have waited impatiently for some elaborated comments from *trusted source* on JWST's observational discrepancies to the post Big Bang galaxies formation theories, but all in vain. Still too soon and risky to draw prematurely some conclusions?
why we aren't building 10 james webb telescopes (or more) is what insanity is.
Red shift doesn't correlate to movement, it's correlation is distance.
I think I know what the lost dark matter is. It’s that Quantum fuzziness when you try to pin down electrons location. Remembering pass spin and pass location because you can’t know where you’re going if you don’t know where you’ve been
this is already included in the fine-structure of atoms. Darwin term / Zitterbewegung
Yes, we get it -- Joe Biden is old. But to put him next to the Webb deep field... come on!
How old is the universe?? Well for comparison here’s a picture of Joe Biden. 😂
Distance doesn't correlate to age whatsoever. Redshift may tell us how far but not movement or age. Great lecture all the same thank you.
light waves traveling through expanding space are stretched , and therefore, red shifted
@clown134 under scrutiny, I know cause I'm one of them. Redshift correlates distance, not expansion. Peace ✌️
@@alex79suited I don't see why expansion would not cause red shift?
Dark matter
The reality is they have no idea if the universe is 13.8 billion years old. It's a guesstimate. It's not science to unequivocally state this as fact.
It’s a high confidence guess you dunce. Light travels at a constant.
The amount of over/under is negligible in time scales that large as well. What’s another million years or so one way or the other compared to billions? A lot of people don’t have a true grasp the difference from 1 million to 1 billion. A million minutes it just a little over one year while a billion is almost 2000 years.
He didn't state it as fact at the beginning, he said "we think it is 13.8 billion years old". It is not a guess but backed by observational evidence. It is the best current figure based on what we know.
The Royal Institution, and he's telling us that "the sun is 8 light minutes away...8 minutes:that's the lenghth of time it takes for light to reach us from the sun.....if the sun were to mysteriously disappear we wouldn't know for 8 minutes.." . Sorry but I'm not a one year old. Can you fix this issue please. I have had to look elsewhere for intelligent and informative dialogue.
If, As above so below, an observed wave need an observer. But the universe does not exist in super posionting before we observe it. So is God the super observer?
no, because the universe does not need an observer . theres no evidence to suggest that it does, and therefore no reason to believe it might. and same for god. no evidence to suggest one exists, and therefore no reason to believe it does
Did Biden pay him to do this lecture? Biden probably wasn't even aware of the JWST
yeah please explain how thats relevant or even probable?
That is one Smug European , if I ever saw one. *oo*aaa*
❤ I friggin LOVE cosmology!
But ya kinda ruined it by mentioning “Joe Biden”. 🤮
Well he did say "it is fair to say that Joe probably did not quite grasp the physics of the image." 🤣 A literal astronomical understatement.
The FPOTUS supports your ongoing interest in cosmetology!
Well that was spupid.