The Dark Universe - with Adam Riess

Leading cosmologists Renée Hlozek, Risa Wechsler, Lucie Green and Nobel Prize winner Adam Riess explore our understanding of dark matter and dark energy.
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We now think the Universe is packed with invisible materials - dark matter and dark energy - pulling and pushing the parts that we see. BBC Stargazing Live and Sky at Night presenter, Lucie Green explores this frontier of understanding with Nobel laureate Adam Riess and leading cosmologists Renée Hlozek and Risa Wechsler.
Adam Riess is an astrophysicist at Johns Hopkins University and the Space Telescope Science Institute. Riess shared the Nobel Prize in Physics in 2011 for providing evidence that the expansion of the Universe is accelerating. More recently, he has also been awarded the Breakthrough Prize in Fundamental Physics, adding to his many awards and prizes over the years.
Lucie Green is a space scientist based at UCL’s Department of Space and Climate Physics. She studies the atmosphere of the Sun, particularly the immense magnetic fields which sporadically erupt into the Solar System. She is also actively involved in public engagement with science, regularly giving public talks and presenting TV and radio programmes.
Risa Wechsler is an astrophysicist and a professor at the Kavli Institute for Particle Astrophysics and Cosmology at Stanford University and the SLAC National Accelerator Laboratory. Wechsler's work combines massive cosmological simulations with large galaxy surveys that are mapping the Universe, to study the nature of dark energy, dark matter, and the formation of galaxies. She is currently leading the science collaboration of the Dark Energy Spectroscopic Instrument, which will make a 3D map of 30 million galaxies to elucidate the structure of the Universe.
Dr. Renée Hlozek is the Lyman Spitzer Jr. Postdoctoral Fellow in Theoretical Astrophysics in at Princeton University; the Spitzer-Cotsen Fellow in the Princeton Society of Fellows in the Liberal Arts and is currently a Senior TED Fellow. In 2011, she received her DPhil in Astrophysics from Oxford University as a Rhodes Scholar from the class of South-Africa-at-Large and Christ Church, 2008. Her research focuses on theoretical cosmology; as a member of the Atacama Cosmology Telescope she measures the Cosmic Microwave Background radiation to decipher the initial conditions of the universe.
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[@chrisofnottingham]

Loving the way he just dives straight in and gets on with it.

[@JustOneAsbesto]

+chrisofnottingham Agreed.

[@pauladamson8952]

@@JustOneAsbesto But it's a pile of errors, starting with the cause of the redshift.

[@cmcgloughlin]

@@pauladamson8952 where do you keep your Nobel Prize? Probably in a better place than his, huh?

[@tantiwahopak101]

@@cmcgloughlin well some scientists are now questioning the existence of dark energy.

[@MrAlcides1611]

Great Lecture! The level is high and it is a pleasure to watch it!

[@JamesHahnII]

I can’t stop watching these lectures.

[@lineikatabs]

The Universe is dark and full of terrors.

[@jamesdolan4042]

Well, I think it's best if you stay here as long as you can. I like what you wrote, but alas you are in the Universe.

[@sajateacher]

This guy is like the Jack Nicholson of astrophysics, "You want the expansion rate? You can't HANDLE the expansion rate!!!!"

[@cmcgloughlin]

Or Wallace Shawn..."the universal expansion is inconCEEVable"

[@hendrikhendrikson2941]

Amazing!

[@EmilMarius1960]

Any wave travel through a material medium. The medium stay, the wave go. What is the material medium of electromagnetic waves traveling through the spatial "void" ?

[@AttilaAsztalos]

Have niggling problem with the Hubble Diagram (yeah I'm dumb what else is new): if redshift tells us speed and luminosity tells us distance, one can see how uniformly expanding space would make those two directly proportional, so we get our nice straight Hubble line when we plot one against the other. However, if we factor in that we see objects further away way back in their past, and that we now assume that the rate of expansion has been changing in time (accelerating) - shouldn't that make the "straight line" actually some sort of curve...?

[@tristbjorn]

The curvature of the line depends on the scales used when drawing it. the Hubble diagram is straight on a logarithmic scale. it would indeed curve on a linear scale, as you mention

[@theDuffChimp]

Basically our understanding of dark matter is equivelant to pre-Newtonian theories on gravity...

[@theblackhole1]

dark energy*

[@alimirza7968]

theDuffChimp ... not pre-Einsteinian?

[@ericselectrons]

Nah, not pre-Einstein. Newton had predictive capabilities with his equations of gravity. We have no current way to predict what dark matter/energy will do, how much it affects us, and how to accurately measure its influence.

[@sammyfromsydney]

Overall a great lecture but I found the description of supernovae as standard candles rather poor. The 1.4 solar mass limit has to do with a type Ia super nova, which is a binary where 1 star acceretes that mass and explodes then and there. There are larger stars that are shorter lived. The way it was phrased seemed to imply any star that is over 1.4 solar masses would immediately (rather than eventually) become a supernova. No astrophysicist would actually think that so I'd definitely say it's just a matter of poor phrasing. A minor but important point.

[@tedsword]

I agree that he raced through the explanation of type 1A supernovae (and that someone who didn't know what it was might be led to believe an oversimplified explanation), but I think he had to race through his explanation because of the short amount of time each of them had to give their talks.

[@KrzysztofKotarba]

where is the desk?

[@TheRoyalInstitution]

+Krzysztof “Kotu” Kotarba It's there, it's just made of dark matter so you can't see it.

[@stefantrethan]

+Krzysztof “Kotu” Kotarba Let's hope Szydlo didn't blow it up, it was a nice desk!

[@danievdw]

So in a nutshell, we don't know anything yet. We can see something ought to be there, but that's it. Could be anything as of yet.

[@michaelsmith6420]

There is several good reasons why understanding the nature of dark energy is not developing as would a real form of energy. The method of analyzing the supernovae events is fatally flawed and so bad it is not even wrong. I learned to avoid these mistakes while in 1st year college physics.

[@khunt2055]

I wish to write a story. I need you to make it mathematically possible. If I wanted to do the Math, I would have stayed in school. 😋

[@fari66tube1]

The farther away galaxy is the greater it's redshift, so the faster moving away. But the farther away you looking the more back in time you are seeing ... It means the closer to the presence time you looking the lower redshift. Which results the expansion of the universe should decreases as the time passes toward the future! Just a simple logic !!

[@jonathanwalther]

You did not use enough exclamation marks. Your "logic" is flawed, as the redshift is not due "to look back in time", it's just an additional effect you have to take into account. You always look back in time (e.g. the photons of our sun need appr. 8,5 min to reach us), but this does not mean it is red shifted.

[@davidhine619]

There is NO Hubble "crisis". Hubble's Constant can be directly calculated using this equation, derived from Maxwell's Aether equations. 2 X a Megaparsec X C, divided by Pi to the power of 21 = 71 K/S/MPS. This is known as "The Principle of Astrogeometry". Hubble's Constant is "fixed" at 71 and does not change with passing time. There is no such thing as "dark energy".

[@durgadasdatta7014]

Read balloon inside balloon theory.

[@jazziejim]

Are stars and planets in a galaxy all moving away from each other too? Why don't we see that? There is space between them.

[@tedsword]

Yes, they are, but by very small amounts. The expansion of space is really, really tiny at any given place, but it is huge when you aggregate that over the vast universe. So the farther away you go, the faster things are moving away from you. Likewise, the closer you go, the less you will notice that change, which is why you wouldn't be able to see the movement between, say, two planets in the same solar system or two stars in a galaxy. The expansion of space is dominated by any local movement close by. For example, the space between us and the Andromeda Galaxy is expanding, but Andromeda's light is blue-shifted, indicating that it is moving toward us. Its overall movement is much greater than the local expansion of the space in between us.

[@jonathanwalther]

25:30 Planets...

[@NineInchRuiner]

* Neil DeGrasse Tyson has entered the chat *

[@jonathanwalther]

@@NineInchRuiner Finally, someone recognized the picture. Congratulations! And has a good musical taste as well. Nice.

[@Tomyb15]

PLANETS? AND YOU SHOW PLUTO?

[@Peter-sj3zi]

It is amazing that scientists can talk so confidently about the universe without knowing more than 95% of the universe. If I were a flog sitting in a deep well, I could also easily explain all my observations by a simple story (say, a big bang or a super flog/God).

[@tedl7538]

Speaking of flogs... I ruv eating flog regs, they learry taste dericious!

[@Peter-sj3zi]

In the future, most of the universe will be too far away from us and we would no longer see it. It implies that the universe we see today may be just part of the whole universe -- much of it is too far away from us. Our local stars will be pulled together by gravity and eventually back to a singularity. This singularity will explore again and expand just like the last time.

[@khunt2055]

I see our universe as a living, breathing, organism. It makes little difference how it ends. Somehow it breaths in and out.

[@iLykeCahrs]

the fourth person never presented?

[@qingyangzhang887]

24:51 The change of accent :))))))

[@witcheater]

It is all a matter of you place in space... and your telemetry. First to understand is that nobody has proven that the Universe is expanding. Saying it is or supposing it is, is not proving, it is just making a conjecture.

[@rationalmartian]

+Gerard Kuzawa Really??? So all the testing, observations and measurements are largely meaningless? You make it sound as if they are simply pulling this out of their arse. I really don't think you know how to science. You're talking complete bollocks. And that's just it, it DOESN'T matter where you are. Everything is moving away from everything else on the larger scales. Did you watch the damn video or what? And what the fuck are you on about "telemetry" FFS. And you have the gall and brass neck to state that most women are stupid. Are you trolling or what?

[@chrisofnottingham]

+Gerard Kuzawa Fred is dead

[@johnsmith5139]

Thank you for editing out the typical 15 minute introductory remarks from some guy no one cares about.

[@youtou252]

Nice ti tz

[@So1ipse]

Thanks to whomever published this! Just one complaint, why didn't the the organisers let Renée Hlozek finish the lecture? Renée's obviously in depth love of her subject just brimmed out and rendered it graspable even by an astro-ignoramus like me! Sadly however, I bailed out of the presentation before the end even despite the interest value of the content, that shrill lecturer at the end was beyond unbearable - I started out with a bit of a headache which had almost got better while listening to Renée Hlozek explain stuff. Unfortunately, back it came, full force, after about 2 minutes of ms shrill-shrieker :-( I don't know if she avoided it through threats of death by shriekage but someone should have fed her some mellow-teacher lessons - or let her carry on researching stuff miles away from the lecture theatre - for others to explain.

[@curiouscat8396]

Bla bla bla. Like a bloody sock puppet. Same ol' S/crap, over and over again. PHR!

[@TravelWorld1]

Smart Jew. We like him.

[@Peter-sj3zi]

I would never believe a story of the universe based on a singularity. If this is true, why not happen again since and why not I have seen one by myself? Before this story, for thousands of years, we were told that the world was created by God. Now we were told that is created by Big Bang. Do we again need a few thousands of years before a new story comes out?

[@Phobos_Anomaly]

It's unlikely, but that's how science works. You discover more and update your understanding.