Unraveling the Universe: Hubble Constant, James Webb, & the Future of Astronomy with Wendy Freedman

Episode Chapters:
00:00 Introduction and Overview
03:52 Wendy Friedman's Early Life and Career Beginnings
10:00 Graduate School Experience
23:00 Joining Carnegie Observatories
30:00 Transition to Observational Astronomy
32:47 The Importance of Cepheid Variables
40:54 Challenges in Measuring the Hubble Constant
44:13 The Hubble Space Telescope Key Project
52:00 Impact of Hubble’s Discoveries on Cosmology
01:05:35 The James Webb Space Telescope and New Observations
01:26:44 The Giant Magellan Telescope Project
01:43:09 Future of Large Earth-Based Telescopes
01:50:00 Conclusion and Final Thoughts

A note from Lawrence:

Wendy Freedman, the former director of the Carnegie Observatories and now distinguished professor at University of Chicago, has been a leading figure in observational cosmology and astronomy for over 30 years. I have known her as a friend and colleague, and have learned much from her over the years, and was very excited to be able to snag her amidst her busy schedule to record a podcast a week or two before the release of a new blockbuster result her team had produced. I am very happy that Critical Mass listeners will be among the first to get the detailed lowdown on the likely resolution of a problem that has been plaguing cosmology for the past decade.

In the 1990’s Wendy led a major international team of astronomers in carrying the Hubble Space Telescope Key Project. The Hubble Space Telescope (HST) was named in part because of this project, to establish the distance scale of the universe and measure its current expansion rate, a quantity not coincidentally called the Hubble Constant, first measured by Edwin Hubble in 1929.

Since that time, different groups have measured this most important single observable in our universe and gotten widely different values. In the 1980’s and early 90’s two different groups got values that differed by a factor of 2, even though each claimed errors of less than 10%. In 2001, Freedman’s team published their result, truly accurate to 10%, and the value, perhaps not surprisingly, fell right in the middle between the previous two discrepant values.

All was good, until inferences based on the Cosmic Microwave Background, the most precise observable in modern cosmology suggested that measurements at a time when the universe was 300,000 years old, when extrapolated forward using the best current theory of cosmology today, would give a value that different from the HST value.

The difference was statistically significant, and as time proceeded, and error bars got smaller, the discrepancy between the HST (and then the James Web Space Telescope (JWST)) measurement, and the CMB measurement got more significant. Was our current model of cosmology simply wrong?

Such was the claim in various places over the past few years. Most recently, Wendy led a team to measure cosmic distances in 3 different ways using JWST, and as she describes in our discussion, it looks like the problem may now be solved, although not without leaving other mysteries.

We talked about a lot more than this though. Wendy’s background, what got her into astronomy, her experiences throughout her career, and her leadership in a new project building the Giant Magellan Telescope, what will be the largest telescope in the world in Chile.

The discussion was as fun as it was exciting. Wendy is a wonderful popular expositor, and as always, I really enjoyed talking to her. Tune in to hear, for the first time, about the newest and most important recent result in cosmology from one of my favorite colleagues and a world class scientist.

[bradcazden]

It bothers me watching Dr Freedman get interrupted so many times. Still a great conversation

[acidrockpro]

She was just speaking and Lawrence just sorta stopped her for some reason.

[douglasstotter]

Very disappointing! Did Kraus speak for 80% of the episode?!?! WAY too many interruptions of the guest; WAY too many unfinished sentences and unnecessary asides from the host. I couldn't listen to the whole thing! SO frustrating!!

[volaireoh]

Please let the person your interviewing talk 😅

[Blackwingk]

I respect you immensely, Lawrence, but c'mon man...give her a chance.

[AsteroidTVGaming]

the amount of enthusiasm between these two guests is evident!! props and thank you for the video!

[HGALAXIES]

Please please please learn NOT to make things about you!!! Remember that the guest is here to TALK, NOT YOU! Ask your question and wait till they're done!!! THANKS!

[hanochlivneh]

Lawrence, you are very accomplished astrophysicist. You also interview well. But you really need to leave more elbow room for your interviewees. Wendy is a topnotch scientist. So please let her talk. No need to introject your knowledge (ideas?) so often!

[TheloniousMonk]

Two very important people talking about a very important subject but in such a confusing and often interrupted manner that one gets completely lost. Dear Dr. Kraus I am one of your admirers but these talks should not be a casual discussion between friends but geared to the audience who wants to understand. The new measurements of the Hubble constant are too important to hide somewhere inside a 2 hour gibberish.

[Phelupianmangler]

Quit interrupting and taking over the interview. It’s always me me me with the host. The self absorption is frustrating listening to.

[julioguardado]

$2B is chump change in our gdp. How many Magellans have we spent on war?

[mikhailfranco]

17:30 LK: "Biology class was just memorizing the parts of a frog - it was offal."

[nunomaroco]

Amazing talk, very important experiments and observatories...

[juligrlee]

I think one of the best things we can purchase for our daughters and sons is a full sized periodic table to hang by your child's bed, especially one that is full of color. Kids don't need to understand the periodic table when they are young but when they are taught chemistry and she sees the periodic table she will feel like the periodic table is her own and want to explore it. I taught 5th grade math and was always surprised how many kids had tons of fear about the multiplication table. Again I feel that hanging this full size table on the child's wall is perfectly logical and helps the kids lose their fears and learn a few math facts. Both of my daughters have advanced degrees in chemistry and have been working in that field for 30 years. My freshman algebra teacher yelled at me for printing with perfect penmanship. I used cursive and only I can read my cursive. I think all kids would better off learning shorthand or court reporting skills so taking notes in college and in lectures would be so much more useful.

[robertkahn]

Put a big note on your desk saying. Let the guest speak.

[ericberman]

I’ve got an idea, how about we have Wendy Freedman interview Lawrence Krause? Oh, wait, that just happened.

[julioguardado]

I love telescopes. Magellan sounds like a beast. I think telescopes are one of the best bang for the buck in scientific research and discoveries. We should spend more on them.

[ericberman]

Can’t wait to hear Wendy Freedman speak during her interview, which is scheduled when, exactly?

[walleviolencia]

I became interested in and have learned so much about cosmology through your excellent content, Lawrence. The Lecture and debate in Stockholm was a peak in this interest, you against the philosophy 😂
Love!

[zhavlan]

Let's work with the postulates of Einstein's theory of relativity.
And if we apply new technologies for this, using the experience of Michelson Morley on the airplane fixing speed 200, 300, 400 m/s., we will see how quantum gravity works. Such measurements are impossible on the satellite due to weightlessness.