Scientists on Reddit

Alex Filippenko

Astrophysicist at UC Berkeley, supernova researcher

How we know it's theirs

The 2014 r/IAmA AMA, posted from this account

We retrieved 3 posts and 182 comments from u/AlexFilippenko, dated 2013 to 2015, most often in r/IAmA, r/space and r/Astronomy.

Best moment

A redditor wrote in r/IAmA

On “I'm Alex Fillipenko, Astrophysist at Berkeley, and contributor to History Channel's 'The Universe', promoting 3.14 pi day! AMA”

What made you decide astrophysics as a career?

u/AlexFilippenko replied

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I've always been fascinated by science. From ages 10 through 17, my main interest was chemistry, but as a freshman in high school I was given a small telescope. With it, I "discovered" Saturn -- the third "star" at which I pointed the telescope! This really jazzed me, and astronomy became a growing interest. In my freshman year of college, at the University of California at Santa Barbara, I took an introductory astronomy course from Professor Stanton J. Peale, and it was truly wonderful. I realized that the physics of the very large is governed by the physics of the very small (atoms and subatomic particles), so by switching to astrophysics I could "have it all." So I changed majors with the intention of becoming an astrophysicist, and I've never regretted the choice.

One final factor in my decision: As a budding young chemist, I played with explosives and had a couple of pretty bad accidents. I realized that I don't have the self-discipline to stay away from dangerous chemicals, so I should switch fields as an act of self-preservation, if nothing else!

More moments

A redditor wrote in r/space

On “I am Alex Filippenko, astrophysicist and enthusiastic science popularizer at the University of California, Berkeley. Today is Astronomy Day, a good public outreach opportunity for this "gateway science," so go ahead and AMA.”

Sorry if this is a stupid question, but if space is a vacuum and air naturally gets sucked into a vacuum what keeps our atmosphere from being sucked into outer space? EDIT: added 1 word

u/AlexFilippenko replied

It's actually a misconception that a vacuum exerts a force that "sucks" air into it. Air can spread out from where it is located, into a vacuum if there's one nearby. But Earth's gravity keeps the air in our atmosphere from spreading out into space.

A redditor wrote in r/IAmA

On “I am Alex Filippenko, astrophysicist at the University of California, Berkeley, and noted science popularizer, celebrating Astronomy Day today. AMA.”

Does the fact that the universe is "flat" suggest that we can put a minimum size on the entire universe that's at least as big as a hypothetical closed universe in which or local curvature is too small to detect with current techniques?

u/AlexFilippenko replied

Yes, that's right. I think current estimates place the volume of the entire Universe to be at least 80 times the volume of the observable part of our Universe. But in fact, the entire Universe may well be far, far…

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Yes, that's right. I think current estimates place the volume of the entire Universe to be at least 80 times the volume of the observable part of our Universe.

But in fact, the entire Universe may well be far, far larger than that, according to inflation models. It could easily be the case that the ratio of the diameter of the entire Universe (all that there is) to the diameter of our observable Universe is as large as the ratio of the diameter of the observable Universe to the diameter of a proton: something like 10^41 for the ratio. In other words, our observable Universe is like a proton relative to the entire Universe. Whoa!

A redditor wrote in r/IAmA

On “I am Alex Filippenko, astrophysicist at the University of California, Berkeley, and noted science popularizer, celebrating Astronomy Day today. AMA.”

Some of my friends have taken your Introduction to Astronomy course at UC Berkeley and loved it. They say that your last lecture is especially inspirational. What do you tell them in that lecture?

u/AlexFilippenko replied

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Well, one of the things I tell them is that each of them is special in a cosmic sense, not just an insignificant speck of dust in the Universe, because they have the intellectual capacity to understand what scientists are learning about the Universe. In a sense, it's as though the Universe has developed a way to know itself, through us. We are the observers of the Universe, the explorers of the Universe, the brains and conscience of the Universe. And it needn't have been like this! Alter the laws of physics ever so slightly, and our Universe may have been stillborn, devoid of such complexity. We were dealt a darn good poker hand, so to speak.