Astrobites at AAS 225: Day 3

Welcome to Wednesday!

Plenary Talk: The Interactions of Exoplanets with their Parent Stars (by Meredith Rawls)

The day started with a talk by Katja Poppenhaeger. She gave a compelling presentation about the different ways stars and planets can influence each other. It was interesting to see how much of the interactions go both ways: it is not just the star affecting the planet, but it is also the planet affecting the star.

Press Conference: Eta Carinae (by Meredith Rawls)

This press conference was all about one fascinating, massive, and extremely energetic star system called Eta Carinae.

The most interesting part was when speaker Thomas Medura pulled out a 3D-printed model of the system. If you have access to a 3D printer, the blueprint is freely available online so you can make your very own Eta Carinae.

Plenary Talk: Inflation and Parallel Universes: Science or Fiction? (by Erika Nesvold)

Max Tegmark, author of Our Mathematical Nature: My Quest for the Ultimate Nature of Reality, gave a fascinating plenary talk about multiverses. He first defined “our” universe as “everything in the observable universe.” If space exists beyond the observable universe, we can’t see it because light from that region has not had time to reach us in the age of the universe. Tegmark then described four “levels” of possible alternate universes, with increasing amounts of controversy and, frankly, weirdness.

The first type of alternate universe, Level I, is just the space that exists past the boundaries of the observable universe. This one’s not very controversial. We can’t observe this part of space, so we can’t scientifically test whether it exists, but it should be space much like our own, with the same physical laws. Inflation predicts that space is infinite, so if you believe inflation (if you can measure other testable predictions of inflation), logic dictates that Level I alternate universes exist. We will be able to observe more and more parts of Level I space as the universe gets older and allows light to travel farther.

Level II universes describe regions in our own space that experienced different amounts of inflation. These regions would be infinitely far away (because you’d have to travel through inflating space to get there), and would have the same fundamental physical laws, but different values for things like the cosmological constant.

Level III universes are probably what you think of when you hear about “parallel universes” from science fiction. These universes are predicted by collapse-free quantum mechanics. For example, if a particle exists in two states at once (like Schrödinger’s cat) and is then measured, two universes may split apart: one in which the particle is measured to be in state 1, and another in which the particle is measured to be in state 2. You can produce a lot of parallel Level III universes this way! This level is fairly controversial, although Tegmark pointed out that the Level III universes should all have the same old boring laws of physics.

Level IV universes are the highest on the weirdness scale. These universes will have different fundamental laws of physics, and we don’t really know what they would look like.

Lunch Interlude: Outreach with Science Train (by Meredith Rawls)

During the lunch hour, a small group of astronomers took to the streets and nearby transit center to proselytize science. This was Lucianne Walcowicz’s idea, and it was a blast. Sometimes you can strike up the best conversations in unexpected places. We talked with folks from all walks of life about everything from the accelerating expansion of the Universe to colonizing exoplanets.


Press Conference: Seminar for Science Writers (by Meredith Rawls)

The afternoon press conference had a slightly different format. Instead of brand new results from the Hubble Space Telescope, this session featured a recap of Hubble’s entire 25-year history. The idea was for science writers to get an opportunity to write a longer piece reflecting on Hubble’s rich history. The telescope truly has played a remarkable role in scientific discoveries and as a cultural icon.


The afternoon plenary sessions included a lot of discussion about cosmology, including Planck results that added more data to support the idea that the universe is flat. Tune in tomorrow for our summary of the last day of talks!

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This post was written collectively by multiple members of the Astrobites team. Meet the authors of Astrobites.

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