Solving the Hubble Tension | Robert Kirshner (400)

Today, we’re joined by a real hero of mine and mentor to millions around the world – dr. Robert Kirshner!

Robert is an astronomer of great renown. He is the Clowes Research Professor of Science at Harvard University and executive director of the Thirty Meter Telescope. This remarkable international scientific endeavor will radically change our understanding of the universe and our place within it. With its unprecedented design, the TMT will feature unique capabilities for exploring black holes, dark matter, and the possibility of life outside the solar system.

Tune in to learn more about Robert’s monumental discoveries and the most controversial telescope on Earth.

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Key Takeaways:

00:00:00 Intro
00:01:12 Judging a book by its cover
00:03:14 The discovery of cosmic acceleration
00:07:53 The history of cosmic expansion, dark energy, and the density of the universe
00:22:36 Balancing confidence and humility in scientific research
00:25:06 Telescope technology and its applications in astronomy
00:34:49 Did the Big Bang never happen?
00:39:37 The most controversial telescope on Earth
00:56:33 What would Robert do differently?
01:00:05 Outro

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[edcunion]

Excellent interview, the view here is Kirshner & Perlmutter's teams' work is one of the best experimental universal tests since Eddington's ~ 105 years ago.

To this humble universal observer, what has been discovered with their accelerating universe measurements is the increase, over time, of universal spacetime curvature. Besides expanding, the universal curvature has been identified, and it is increasing. This makes sense where bosons/photons traverse the universe in no time from their viewpoint, whereas fermions accelerate through the universe at sub- light speeds from a snail's to Planck's, along curved paths as they free fall en-masse or as individual particles, as witnessed, seen, by free-falling observers!

[bobjohnson]

Dr. Kirshner being open to being wrong on his assumptions is refreshing.

[nicholassuntzeff]

I seem to be known as the Eeyore of astronomy. When I was Vice President of the AAS, someone put a little Eeyore at my seat just before the meeting started. No one owned up to it. I figure it was Bob. It is now in my office.

But to be more serious, I was not just an obsessive photometrist, and I get tired of that stereotype. I knew the physics and electronics of CCDs, some of it from Don Groom, who was on Saul's team and a friend. 1993 we were winding down the Calan/Tololo SN survey at CTIO - Mario, Mark, Jose, and me. Our goal was to calibrate Type Ia supernovae and measure the Hubble constant. We nailed the calibration and the Hubble flow, but the Hubble constant had to wait for the Cepheid distances published by Wendy Freedman et al. 8 years later. The obvious next step after the Hubble flow was to measure q0. David Spergel has suggested that z~0.3 was a sweet spot. I could barely reach that with the 24/36" Curtis Schmidt at CTIO, and I needed to build a prime focus CCD camera, which I did that year. Brian Schmidt came down in 1994 to CTIO. He had become a good friend by then, and in a discussion in April 1994, we decided that it would be more efficient to use the 4m Blanco to go to z~0.5 to find the supernovae. We could do this in a few nights, whereas the Curtis/Schmidt would take much longer because we had to search more sky. We should get about 1 SN per sq-deg on the 4m. So Brian and I combined our Chile Calan/Tololo team, Brian's collaborators, and ESO collaborators into the High-Z Team. The original application for telescope time can be seen on Wikipedia.

When I was a Carnegie Fellow at Mt. Wilson, Allan Sandage told me that my quest in astronomy should be to measure H0 and q0. That's what I wanted to do, and our teams did exactly that.

When Brian and I assembled the team, I wanted and Brian agreed, on two ground rules. (1) the team would be divided up geographically - Chile, Harvard, Washington, ESO, Berkeley, Hawaii, etc. Every six months, the team would work for that one geographical subgroup. I made a list of the subteams. (2) We would always put the intellectual leader of that 6-month effort as the first author. I wanted to avoid senior astronomers getting credit for what was a team effort. And in the end, almost all our papers had grad students or postdocs as first authors. In the second semester of 1997, the teams shifted to UC Berkeley, where Adam and Alex worked. And the rest of the story, you know.

Is it fair that only two people on our team won the Nobel? No. But Brian and Adam are the right ones. Absolutely, if you have to choose two. But yet, it was a team effort. If the Nobel goes to the whole team, then that will dilute the impact of the prize. So, no solution is fair, really. A member of the Nobel committee did tell me, however, that they were very aware it was a team effort, and because of that, for the first time, a team was clearly mentioned in the Nobel description of the science. This was a controversial step for the Nobel committee at the time. Now, it is commonly done in the announcements.

[karlgoebeler]

Distribution of energy across Maxwell in the bound state. Creates the "Speed of Light" interpretation of phenomenon

[kai]

Culture and Science can co-exist on the Mauna.

[JungleJargon]

Albert was right, the cosmological constant is a fudge factor. A deeper understanding of gravity gives you a deeper understanding of the universe. The earth is flat locally the same as the speed of light is the same locally but not on a larger scale. The earth is round on larger scales and the speed of light depends on the measures of time and distance which change depending on the amount of gravity in the surrounding area. This means that distant starlight arrives instantaneously from distant galaxies which aren’t as far away as they appear to us to be with our measures of time and distance and the time is also passing by at a much faster rate since there’s no matter between us and distant galaxies to slow down time or shorten distance according to general relativity which is now an observation and not just a theory. …and the converse of things approaching a black hole look stopped to us because of how slow they are moving.

The changes in time and distance compound the changes in the speed of light as observed from our frame of reference. Do a thought experiment. Hold your hands a foot apart representing 186, 000 miles saying “one thousand and one” representing one second while pretending to see an imaginary photon going from one hand to the other. Now expand the distance saying “one thousand and one” as fast as you can. You should notice that the speed of the imaginary photon increases the more distance expands and the more time speeds up just same as the farther away from the center of the galaxy it is. The opposite is also true. Someone moving in the direction of a black hole will seem to us to be stopped. *If you change the size of a cubit you will change the size of the house that you build with it.* 🏡🏠

[karlgoebeler]

Still prefer the personal one I was working on. Site selection "Up in the Air". Pair of telescopes mounted on a "Hotrod" Laser collimated of course. Double use as a collision avoidance system.

[TokamakPolywell]

In a multiverse interpretation could not dark energy expansion of one universe be attributed to merging with a larger universe and pressure differential? Seems like other interactions would not produce an outcome of expansion.

[karlgoebeler]

Open the Pod Bay Doors Hal. Yes a large set of "Pinpoints of light" of various magnitudes.

[karlgoebeler]

Correct. Morphing into a conversation. Apologies for the delay. Did see the reference

[koerttijdens]

2, 65 billion, no problem, we gotta follow the seance.

[nunomaroco]

Hi from Portugal, tremendous talk....

[karlgoebeler]

Bound and unbound state. Bees in the Box concept Mass in the equations becomes defined as frequency's of a photon

[suleymanpinarli]

So nice to see such humble intellectuals. I really enjoyed my very limited understanding :)

[JungleJargon]

The energy of the universe is in the black holes that are growing whether they absorb matter or not because they are absorbing space time causing the vacuum of space. The universe isn’t expanding into oblivion for no reason. The redshift is because there’s more matter out there than there is in our universe. The farther away the more matter there is compared to the mass of our universe. Of course there’s no need for dark matter when the amount of gravity determines how fast things move in space including light.

[karlgoebeler]

Reconciliation of General Relativity and Quantum Mechanics. The story which I have learned is that is defined as a point source of Energy revolving around a True vacuum (Permittivity of Space) {Learned it as the standard of Capacitance in electronics}, in a false vacuum with angular momentum of Z. Apologies if I am wrong.

[RWin-fpjn]

So I like best when Robert stresses we should be more openminded and tolerant of new ideas. Well indeed, but this should not be understood as add-on ideas only. This should first and foremost apply to the things we take for granted and then we will find academia far from openminded. Point and case: the vacuum energy being off by a factor or 10^120. !! Well it is only because we ASSUME the observed redshift of furthest galaxies is caused by an extra galactic doppler effect in which case spacetime expansion and thus dark energy are follow-up assumptions. But how sure are we this redshift of incoming photons isn't caused by a Fraunhofer-like diffraction effect INSIDE our own galactic plane? Much like a fish looking at the outside world through its curved glass, our vision would NOT reflect reality. And Lord knows we got a warning with the EHT telescope recently showing our sag A* BH getting an optical 90 degrees diffraction distortion. This 90 degrees distortion would also cause the light it bends to appear yellowish (i.e. the central galactic bar]. This is due to the light tangent to its kerr singularity rotating event horizon will get its virtual arc speed pointed away from us, making it appear more redshifted as it is further away from sag A . The same likely happens at the edge of our galactic plane. So redshift would be a Milky Way optical illusion, where redshift it is indeed a sign of DISTANCE, not speed of furthest galaxies. Cosmologist should rejoice getting rid of the 10^120 vacuum energy, right? They haven't thought this option through for 100 years. We all make mistakes. time to correct some now and have some of that self-declared humility and open mindedness…we need progress now gentlemen.

[mcasanovaiii]

Doc,
I have a fun tidbit of intellectual hobbyists. I just saw a brand new movie involving our impossible communions underpinnings. The movie is, The Imitation Game, and if you have not enjoyed this production you might want to on your leisure time. Alan Touring is the subject and it is a version of his story in Cinema form. I found it inspiring in many aspects for humanity and impossible tasks.

[francesbrezner]

Thank you so much for this discussion! I enjoy hearing the state of the art in astronomical instruments as well as current thought in the theroretical realm. And of course with the experimentalists!

[gasdive]

It should have been put in space. It would have been much cheaper, gone forward faster, not need adaptive optics, work in more frequencies and work 3-4 times more hours per day.

That's even before you consider the occupational and oppression aspects involved in crushing the local people.