Alex Filippenko

Today with us we have an amazing speaker: Dr. Alex Filippenko

Alex is a Professor of Astronomy at UC Berkeley. Throughout his career, he has won a number of prizes, the most noteworthy the 2015 Breakthrough Prize in Fundamental Physics. He is also famously known for being part of the History Channel series “The Universe”.

Alex has been interested in science since a young age. His first passion was Chemistry when he was in middle and high school, and then progressively he moved towards Astrophysics in college. The very first time he used a telescope, he looked at the night sky and was amazed by his “discovery” of Saturn! 

Upon finishing his PhD thesis (which was focused on studying powerful supermassive black holes at the center of galaxies), Alex was still gathering data for some of these galaxies. Then, in the last hour of his last night of observation, he was faced with a choice – which galaxy to observe next? He had hundreds of them on his list. Only two could be observed that night at that moment. He picked one. Unexpectedly, there was an extra bright star at the center of this galaxy, which turned out to be an exploding star! He had discovered a supernova, of a weird new type (supernova type Ia). This changed his career!

Why are these exploding stars so important? Supernovae create, during the explosion, and eject into space the very elements of which we are made of. The carbon in our cells, the oxygen that we breathe, the calcium in our bones, the iron in our red blood cells. All these elements are cooked up through nuclear reactions deep inside stars. And if they weren’t to explode, these elements would not be available for the formation of new stars, planets, and ultimately life. In a sense, by studying exploding stars, we study the very origins of humankind.

The most important discovery in his career was the one he made, along with his postdoctoral scholar Adam Riess, of the accelerating expansion of the Universe. They took a sample of exploding stars and measured how bright they appeared to be. Since they knew how powerful they really are, they could figure out how far away they are, and how quickly they are moving away from us.  By studying several supernovae at different distances, they were exploring the past history of the expansion of the Universe. And they found that the Universe is expanding faster now than it was four or five billion years ago! This was extremely weird, as normal gravity tends to slow things down, not to accelerate them. This discovery led to the idea of dark energy, an energy of a repulsive nature which was accelerating the expansion of our Universe!

After several years as an esteemed professor, Alex still loves observing, or the “simple act of gathering photons” as his PhD advisor Dr. Wallace Sargent used to say. He is also very famous for being a great science communicator and does not shy away from answering questions from non-astronomers. He tells us that he is often faced with a question about the possibility of life elsewhere in the Universe. Turns out it’s not an easy one to answer. In his words: 

“It’s complicated. You know, microbial life might be quite common. Although even that we’re not sure about. I actually think that intelligence at our level, and mechanical ability at our level, is quite rare. For example, there have been more than 10 billion species of life on Earth, over

the history of Earth and nothing, as far as we can tell, has reached our level of intelligence

or mechanical ability. Moreover, we’re relatively late in the development of life on Earth. Thirdly, we are not a clear long-term evolutionary advantage. We have improved the lives of hundreds of millions of people on Earth, but we’re also the first species that can, and possibly will destroy ourselves. Finally, you know, if they’re common out there, then you get into the Fermi paradox: where are they, if they’re that common?” 

He also underlines how he is an astrophysicist NOT an astrologer. So don’t go to him for palm reading! 

In the end, we all know astronomy and astrophysics are very difficult fields, but Alex gave us some advice in case we are interested in joining: constantly be on the lookout for opportunities and take advantage of them when they fall on your lap! The same way he was ready for the opportunity to discover an exploding star while looking for supermassive black holes! 

Finally, If you ever needed a reason to take up astronomy, here is what Alex would tell you:

We are made of star stuff! Doesn’t that grab you?

As an astronomer you have the whole Universe to explore!

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