When galaxies were born - with Richard Ellis

Подписаться 1,5 млн

Просмотров 80 тыс.

50% 1

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.
Subscribe for regular science videos: bit.ly/RiSubscRibe
--
A very special thank you to our Patreon supporters who help make these videos happen, especially:
modsiw, Anton Ragin, Edward Unthank, Robert L Winer, Andy Carpenter, William Hudson
Don McLaughlin, efkinel lo, Martin Paull, Ben Wynne-Simmons, Ivo Danihelka, Kevin Winoto, Jonathan Killin, Stephan Giersche, William Billy Robillard, Jeffrey Schweitzer, Frances Dunne, jonas.app, Tim Karr, Alan Latteri, David Crowner, Matt Townsend, THOMAS N TAMADA, Andrew McGhee, Paul Brown, David Schick, Dave Ostler, Osian Gwyn Williams, David Lindo, Roger Baker, Rebecca Pan
--
The Ri is on Patreon: / theroyalinstitution
and Twitter: / ri_science
and Facebook: / royalinstitution
and TikTok: / ri_science
Listen to the Ri podcast: anchor.fm/ri-science-podcast
Our editorial policy: www.rigb.org/editing-ri-talks...
Subscribe for the latest science videos: bit.ly/RiNewsletter
Product links on this page may be affiliate links which means it won't cost you any extra but we may earn a small commission if you decide to purchase through the link.

Наука

Опубликовано:

10 май 2023

Ссылка:

Скачать:

Готовим ссылку...

Добавить в:

Мой плейлист

Посмотреть позже

Комментарии : 90

@gustavderkits8433 Год назад

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.

@andycordy5190 Год назад

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

@0.618-0 Год назад

In this Space Time, to be a human seems absolutely wonderous, is absolutely grand.

@z3et Год назад

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!

@HatchetHMC86 Год назад

Great lecture, love when stuff like this gets presented so well. Many thanks

@johnwishart7950 Год назад

great lecture so interesting so much better than the television

@iraklikavelashvili1593 Год назад

Great lecture, enjoyed a lot!

@tiadiad Год назад

Enjoyed it! Thank you.

@donleavell 5 месяцев назад

Very excellent and informative presentation. Thank you thank you.

@stooartbabay Год назад

Awesome chat :)

@user-mx4kk5mm1x Год назад

Thank you! Cheers.

@bernstock Год назад

Brilliant speaker!

@oskarskalski2982 Год назад

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.

@onebylandtwoifbysearunifby5475 Год назад

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.

@oskarskalski2982 Год назад

@@onebylandtwoifbysearunifby5475 someone watched Dr Becky;).

@onebylandtwoifbysearunifby5475 Год назад

@@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. ;)

@oskarskalski2982 Год назад

@@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.

@onebylandtwoifbysearunifby5475 Год назад

@@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.

@arenje1 Год назад

Amazing

@olgamedland Год назад

fascinating

@onebylandtwoifbysearunifby5475 Год назад

Gandalf gave a good lecture here. Well above average, with enough specific detail to keep even seasoned people interested.

@yanikkunitsin1466 Год назад

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.

@MikeWells420 11 месяцев назад

Gandalf 🤣🤣🤣

@michaelmcveigh8880 8 месяцев назад

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 ...

@YouMessiah 9 месяцев назад

Does this mean that space has expanded quicker than the light from those early galaxies?

@newklear2k 4 месяца назад

I'm watching this in Launceston, and even I'm not sure Tasmania exists.

@drewishaf Год назад

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.

@borisjohnson1944 Год назад

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.

@drewishaf Год назад

@@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.

@prof.crastinator Год назад

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.

@prof.crastinator Год назад

@@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.

@elisejaudon925 Год назад

I've seen other lectures that say the opposite. The galaxies were very large. Much larger than anyone expected. That was just days ago .

@cinemaipswich4636 Год назад

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?

@JoeMicroscope 8 месяцев назад

I can’t watch this because the google adverts are too loud.

@MyRadDesign Год назад

The power of a telescope is roughly proportional to the square of the radius of the primary mirror.

@FreestyleSport101 Год назад

Is this the same area of space seen from hubble ultra deep 2012?

@mrp8811 3 месяца назад

i want more from the Royal Institution.

@noneofyourbizness Год назад

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.

@stargazer4023 8 месяцев назад

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 RU-vid.

@DrDeuteron 5 месяцев назад

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).

@DrDeuteron 5 месяцев назад

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.

@kloug2006 9 месяцев назад

When galaxies were born, I was very young.

@PedroDiMaggio-dk4lb Год назад

Is his analysis outdated because of JWT?

@NondescriptMammal Год назад

How can space itself be expanding, when space is not a material entity?

@koenth2359 Год назад

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%.

@burrito-town Год назад

Why is the audio in this video nearly inaudible? Whoever is in charge of exporting videos for RU-vid at the RI needs to figure out the proper audio settings. This is an amateur mistake.

@utah133 Год назад

We pretty much know how things evolved after the singularity, but will we ever know it's origin?

@awebmate Год назад

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

@clown134 6 месяцев назад

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

@awebmate 6 месяцев назад

@@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.

@nealfeatheringill2091 Год назад

Hes talking about a bunch of stuff we already heard

@Avenged666 Месяц назад

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.

@tvviewer4500 4 месяца назад

why we aren't building 10 james webb telescopes (or more) is what insanity is.

@Time.Traveller. Год назад

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?

@alex79suited 11 месяцев назад

Red shift doesn't correlate to movement, it's correlation is distance.

@user-qq3bl6py3g 8 месяцев назад

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

@DrDeuteron 5 месяцев назад

this is already included in the fine-structure of atoms. Darwin term / Zitterbewegung

@burnere633 Год назад

Yes, we get it -- Joe Biden is old. But to put him next to the Webb deep field... come on!

@theozarktrekker Год назад

How old is the universe?? Well for comparison here’s a picture of Joe Biden. 😂

@ArtDocHound 8 дней назад

Dark matter

@PedroDiMaggio-dk4lb Год назад

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.

@Just.A.T-Rex Год назад

It’s a high confidence guess you dunce. Light travels at a constant.

@Just.A.T-Rex Год назад

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.

@borisjohnson1944 Год назад

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.

@alex79suited 11 месяцев назад

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.

@clown134 6 месяцев назад

light waves traveling through expanding space are stretched , and therefore, red shifted

@alex79suited 6 месяцев назад

@clown134 under scrutiny, I know cause I'm one of them. Redshift correlates distance, not expansion. Peace ✌️

@clown134 6 месяцев назад

@@alex79suited I don't see why expansion would not cause red shift?

@samstvshow 27 дней назад

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.

@JonoTheVoiceofAustralia Год назад

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?

@clown134 6 месяцев назад

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