Q&A - The Dark Universe - with Adam Riess

Lucie Green chairs a discussion between Adam Riess, Risa Wechsler and Renée Hlozek on dark matter and dark energy.

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.

Follow our speakers on Twitter:
@reneehlozek
@RisaWechsler
@Dr_Lucie

[lineikatabs]

Renée Hlozek is an amazing public speaker! I would love to read/listen more from her! Please invite her over more. Also, Risa Wechsler, fantastic scientist and good speaker as well, but she should really learn how to use a microphone. My ears are in pain.

[rationalmartian]

Some really great questions. But much more impressive is the answers. This has to be the most and best explained Q and A on these subjects, certainly that I've seen in a long time. All three do some simply superb analogies, break downs and explanations.
Brilliant.

[eskileriksson]

Brilliant Q&A. The original lecture is of course needed to understand it, but this was so much better.

[sumotherdude]

this is freaking amazing. can't believe i just found this channel but glad i did!

[sanjchiro]

All this talk only tells me that the nature of DM is so completely weird that not only is the idea that it consists of 'particles' probably way off but that ALL of our 'best ideas' are probably only barely touching on what DM is/isn't. It's like trying to measure 'consciuosness' or 'life' is...we really have no good ideas anymore

[jomen]

I like it that Adam Riess points out at 27:30 to 29:40 that the "fine tuned" universe and multiverse etc are not scientific statement, but philosophical speculations. I wished this was more recognized when people argue about these things, because you often hear the claim "its been proven" or "must be so" according to science, which is utter scientific nonsense since we have no evidence to support it, nor evidence to rule out other possible explanations.

[RayVRoberts]

Can you invite this group back for an update? This talk is 3 years old and advancements since then have been amazing...

[faritube]

Are you sure that univers is expanding ? 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 ... and the closer to the presence time you looking the
lower redshift. Then the results showes expansion of the universe is decreasing
as the time passes toward the presence and in the future! Just a simple logic !!

[gustavomoretto]

Fantastic job both by the audience's questions and by the clear and illuminating answers. If chance plays a role in the universe, this encounter ranks among the special ones.

[WayneJohnsonZastil]

I can see dark matter and energy. Just most humans are not clever enough!

[TaylorWJ]

The Q&As add to the enjoyment of the main lecture. Thanks

[ozdergekko]

One of the multiverse theories says that new universes might spawn within our own universe. If this were reality, a) would it have any influence on our universe (such as causing expansion/inflation, dark energy and so on), and b) would it effect the path of light?

[erikziak]

What exactly is the difference between the big rip and heat death? Are they not basically the same event,  just interpreted from a different viewpoint? I find it really hard to write down my thoughts, but I have a complex picture of similarities, but maybe I am just wrong.

[crazieeez]

Matter (visible and dark matter) stay constant throughout the history of the universe. Dark energy increases. So the early universe, matter (visible and dark matter) made up to of the universe and dark energy made up to until recently, it is 72% dark energy and 28% matter.

[RakidulAlam]

RI Renee Hlozek should be invited in RI for one more time.

[jk]

Well, if everyone is so keen on everything being (more or less) symmetric, and they agreed, that you have particles, which have a non-0 mass, and gravitons causing those particles to attract each other, with a weak force (gravity), why not consider having an another weak force, which causes parts of the space having 0 mass, to repell each other?

[PongoXBongo]

To sort of put the gravitational lensing of the CMB into the arrow analogy, it would be the wind blowing the arrow slightly off to the side. If you know the wind conditions at the time the arrow was loosed, then you should be able to more accurately predict where precisely the archer was positioned. Modern soldiers do this to locate distant snipers, for example.

[En-ofoh]

32:27 of course, excellent answer that gives new meaning

[vicachcoup]

23:00 great question. The answers were striking in their lack of considering an intelligent creator. This shows the huge bias of many scientists.
There is no supporting evidence for the multiverse but it is interesting to see how keen scientists are to reach for this as an answer.

[piccolonijel]

I love science, but I want to know the girl who asked the first question either