Starts With A Bang! » Video Ethan Siegel's blog/video blog about Cosmology, the Universe, and everything else Sat, 04 Apr 2009 20:12:38 +0000 en Weekend Diversion: Is There Anybody Out There? Sat, 18 Oct 2008 18:39:04 +0000 ethan I finally found the time to go out an get an electric guitar; my old Ibanez had been on the fritz for over a year, and I just haven’t been on the ball. Here’s my “professional” (e.g., on the internet, possibly still in my pajamas on a Saturday morning) debut. I thought it’d be nice to take a beautiful Pink Floyd song that’s also a very profound question, and show you, in a video, a little bit about where living things could be in our Solar System, if, in fact, there is anybody out there…

Enjoy your weekend!

Genesis Teaser Trailer is Up! Fri, 18 Apr 2008 09:05:12 +0000 ethan What is the future of this website? I’m going to be creating videos for the web about the Universe. I’ll be answering questions ranging from what the Universe is like today to how it got to be that way. I’m going to address every step that we know of, from the Big Bang up to the present day.

And I’m going to do it naturally, by telling the story as the Universe tells it directly to us. I call this project Genesis. Check out the teaser trailer below, and tell your friends, because this is coming in January.

Afraid of the Dark? Tue, 11 Mar 2008 19:03:29 +0000 ethan So I gave a public lecture last (Monday) night called, “Afraid of the Dark: How We Know What We Can’t See” and videotaped it. Now, I’m pretty good at what I’m doing right now (research in theoretical cosmology), but I’m really good at public speaking and teaching, and here is me telling a public audience all about dark matter, how we know it exists, what makes it different from normal matter, and what I’m trying to do to find it/discover its nature for a good 40 minutes. (The intro and question/answers are cut out).

It was a lot of fun; the audience was wonderful, and actually kept me for more than a half hour after my talk ended, asking questions that they were curious about! The video and audio qualities are not the best, but if you have 40 minutes and a pair of headphones at work, check it out. We’ve got a (60 Meg) video of the event right here… enjoy!

Alternatively, you can see it in 4 separate youtube parts (below):

Weekend Diversion: Video Editing = Musical Talent? Sat, 08 Mar 2008 09:05:38 +0000 ethan Sometimes I wonder if I’m going to need to learn video editing to make this outreach thing work. I might do well to follow the lead of this guy, who’s a Norwegian named Lasse Gjertsen, and who’s posted a video of him “playing drums and piano.”

Well, playing drums and piano kinda. But damn, I would love to have those editing skills…

Bring him to me! Fri, 29 Feb 2008 22:06:20 +0000 ethan The Milky Way galaxy is a relatively big spiral galaxy. So is Andromeda. There are about 20 dwarf galaxies that are gravitationally bound to us; combined with us, all of this makes up the local group. But Andromeda is moving towards us, and eventually, it’s going to merge with us. I’ll once again show you a video of what this merger might look like:

But what would we see, here in the Milky Way, as Andromeda got closer and closer to us? Right now, Andromeda looks like this:

But Andromeda is also very far away: about 2.3 million light years (770 kpc). The center of it is tiny on the sky, but the whole galaxy, as seen above, is actually 4 degrees across, or eight times larger than the diameter of the full moon! Its apparent magnitude is 4.4, which means it can barely be seen with the naked eye (anything less than 6 can be seen with your eye) if your vision is good and there’s no light pollution.

But the Universe will continue to age, and gravity will basically tell Andromeda “Get over here!” When this happens, Andromeda not only gets closer to us, but also starts to appear bigger and brighter in the sky. What does this mean? Let’s play Zeno’s Paradox, and see what happens when it gets halfway to us, and then halfway of that distance, etc.

  • About 1.9 billion years from now, Andromeda will be 385 kpc away from us. It now has an apparent magnitude of 2.9, which means it’s just barely visible from most urban neighborhoods, and appears slightly brighter than our own Milky Way does. It now takes up 8 degrees on the sky, making it 16 times as large as the Moon in diameter.
  • About 2.7 billion years from now, it will be within 190 kpc of us. That’s still well outside the Milky Way, which is less than 20 kpc in radius. It’s now quite bright, though, with an apparent magnitude of 1.4, making it as bright as one of the brightest stars in the sky, Regulus. It is now 16 degrees on the sky. If, at this point, it were oriented face-on to us, it would take up about 1% of the entire visible night sky.
  • About 3.2 billion years from now, it will be under 100 kpc from us. It now takes up 1/20 of the entire night sky, and only the Moon, the Planets, and three stars, Sirius, Canopus, and Alpha Centauri are brighter than Andromeda appears.
  • 3.4 billion years from now, Andromeda will be within 50 kpc of us, on the verge of beginning to merge with us. (Remember, it has a radius of about 20 kpc, too.) Its apparent magnitude is -1.5, meaning that it is now brighter than any star in the sky. It will now take up about one-fifth of the night sky, and will just begin to create new star-forming regions in the outskirts of the galaxies, where the gas begins to merge.

And then the merger happens. What will that do to us? Take a look:

Although we don’t know exactly what’s going to happen, it’s a good bet that we won’t want to be here for it. Time to find a new galaxy… or at least a temporary home outside of ours while that merger takes place!

Lunar Eclipse: Clouded out here! Thu, 21 Feb 2008 03:37:43 +0000 ethan I was driving home from work at about 6:30 today and noticed the Moon, still orange, hanging low on the horizon. The lower left corner was just starting to be shadowed by the Earth. As it rose a little higher, it turned yellow and then white, as we learned it should.

Then we got clouded out, and right now, during totality, the entire sky is covered in clouds. But I started thinking, “What if I were in space?” Well, the Moon appears red/orange every day during Moonrise/Moonset from Earth, but would appear white from space. But the red/orange during a total eclipse? The Moon would still be that color even from space during an eclipse! Even to a Venusian or a Martian! In fact, to someone anywhere in space, a total lunar eclipse would be the only time the Moon would appear reddish/orange.

That’s all; a quick post because I thought that was neat. Hope your eclipse-watching goes better than mine!

UPDATE: Orbiting frog has a few things to say about that, but one thing they have is a (computer generated) video of what watching the lunar eclipse might be like from the surface of the Moon! Take a look below:

And if you haven’t gotten enough Astronomy yet, take a look at this week’s Carnival of Space, where they link to my awesome post about why we need dark matter!

Dangerman Audition! Mon, 18 Feb 2008 01:05:16 +0000 ethan Alright, folks, so last week I got this letter from a very good magician and television producer Anthony Owen from Objective Productions, the company partnered with Discovery Channel to make Dangerman in London:

Thank you for your recent email application for Dangerman.

If you are still interested in being considered for this role we’d like you to make a short video of yourself (no longer than 3 minutes). Tell us, on camera, why you would be the perfect Dangerman (or Woman) and explain the science behind a dangerous stunt in an entertaining way which would make sense to a non science-educated viewer.

If you already have footage of you performing the stunt you are explaining or another similar one, you could supply that too, but it’s not essential and no particular preference will be given to applicants who supply ‘stunt’ footage.

After debating exactly what they wanted, I decided that they were most looking for a short video of just me, speaking to the camera, to assess whether I was what they wanted or not. Here is my audition for Dangerman.

Here is a video of someone actually dipping their hand into lead, and you’ll notice he makes sure to wet his hand first! This would really be a dream job if I could get it; wish me luck! In fact, I’m not sure whether it would help or not, but if you wanted to email Anthony and tell him you saw my youtube video and would love to watch Dangerman hosted by me, it couldn’t hurt. I’ve already talked to Jamie about it and she would be happy to come with me to London; let’s hope it happens, since this really would be a dream job for me!

Weekend Diversion: The smartest fish ever? Sat, 16 Feb 2008 20:11:05 +0000 ethan So I am preparing an audition video to be Dangerman this weekend, which will go up on youtube and get posted here next week. In the meantime, as promised for the weekend, I have a new weekend diversion for you: the archer fish, a.k.a. toxotes jaculatrix (hee hee). But what makes it so cool? Oh, I don’t know, how about this slow-motion video:

Did you see that?? It’s a fish that hunts insects by shooting them with water, and then eating them when they fall into the water, often catching them before they ever leave the air! What’s really amazing about this is that the fish needs to be able to “shoot fish in a barrelin reverse.

Shooting anything either from air into water or from water into air is actually really difficult, because light refracts, or bends, when it changes from traveling through one medium to another. The reason it happens is because light travels at different speeds in water than in air (see the hypnotic animation at right), and the scientific law for how it happens is called Snell’s Law.

Does that mean these Archer Fish are programmed knowing how to do this in their heads? No, of course not! Young Archer Fish travel in schools, shooting randomly upwards at insects, and the ones that are the best shots, the fastest feeders, and the most successful at avoiding predators are the ones that survive to adulthood, and those are the ones that can hunt like in the video! Of course, at this fish farm in Malaysia, they teach Archer Fish to hunt in packs even to adulthood, they could be the world’s smartest fish!

Galaxies are made exactly how, now? Wed, 13 Feb 2008 22:58:34 +0000 ethan Last week, Jamie (my significant other) came home from work and told me about a conversation she had with her coworker, Chris. This week she asked another one, Miguel, whether he had any questions about Astronomy, Physics, space, etc. This week’s question comes from Miguel:

What is a galaxy, anyway? Why does it look like a big bright fuzzy star? And why are there different types of galaxies; shouldn’t they all be the same?

This might come as a surprise, but 100 years ago, it was pretty much accepted that we were the only galaxy in the Universe. In fact, there was a great debate in 1920 on whether some funny-looking things in the sky were other galaxies, or whether we were the only one.

So here’s the deal. You look up at the sky, and all those points of light you see are either planets (left) or stars (right).

But with a telescope, you find that there are some fuzzy things in the sky that don’t quite look like you’d expect them to. There are star clusters, like the Pleiades. And there are the bizarre looking objects known as nebulae. There were planetary nebulae, like the Crab Nebula (M1), but there were also things known as spiral nebulae, like Andromeda (M31), to the left.

Sure, we know today that Andromeda is a galaxy and the Crab Nebula is the remnant of an exploded star, but how do we know that? The Milky Way is our collection of about 400,000,000,000 stars. Some of those stars are known as Cepheids, rare stars that flare brightly at predictable intervals. By 1925, Edwin Hubble had found 10 Cepheid stars in Andromeda, and measured their periods and brightnesses over long times, figuring out that Andromeda was both very large and far enough away that it was outside our own galaxy.

It didn’t take long for people to figure out that Andromeda also had a few hundred billion stars in it, and that not only were all the other “spiral nebula” actually spiral galaxies, like the Whirlpool Galaxy (M51) shown here:

but that galaxies, these huge collections of millions or even billions of stars, existed with a really wide variety of shapes and sizes. In addition to spiral galaxies, there are also elliptical galaxies, like the galaxy Centaurus A shown below:

So we’ve got spiral galaxies and elliptical galaxies as the two major types of galaxies in the Universe. Spirals are shaped like a disk, usually with a bulge and sometimes with a bar in the center, with big, bright arms spiraling outwards from the center. On the other hand, ellipticals are shaped like an American Football, with a big bright center becoming dimmer and more diffuse towards the edges. Let’s show you how you form a galaxy, and then why some of them wind up as spirals, while others become ellipticals.

When the Universe is very young, it’s also very smooth, but there are regions of space that contain more matter, both dark matter and normal matter, than average. There are also some that contain less matter, and the famous picture at the right shows you the average places in green, the below-average places in yellow/red, and the above-average places in blue. Each individual overdense (blue) place, where there’s more matter, is going to collapse under its own gravity.

If the overdensity were a perfect sphere, everything would collapse to a point at the center. But one direction, randomly, will always be shorter. Because it has less distance to go, that direction collapses first, and we go from an ellipsoid:

to a “pancake,” or a disk, because gravity squashes it in the shortest direction. When all that matter meets up, the dark matter just passes right through, but all the normal matter (protons, neutrons, electrons) can’t just pass through each other, just like your hands can’t pass through one another. So they stick together, and start forming stars, producing a whole bunch of light in this disk:

The disk then rotates, by the law of conservation of angular momentum, and the rotation makes the spiral structure we see, since the inner part rotates with a higher angular velocity than the outer part. So, what we wind up with is a spiral galaxy surrounded by an ellipsoidal halo of dark matter:

And that’s how we get spiral galaxies! Wait a minute, then, so how do we get elliptical galaxies, and why are there so many of them in clusters, but when we see galaxies on their own, they’re almost all spirals? We think that all galaxies start as spirals, but some of them merge together. When you get a small galaxy merging with a big one, the small one gets destroyed and the large one is mostly unaffected, like the large Magellanic Cloud falling into the Milky Way. But when you get two large galaxies merging together, they destroy the spiral structure and make an even bigger elliptical galaxy, as this video shows what might happen to our Milky Way were we to merge with Andromeda:

So, to recap, galaxies are collections of millions, billions, or trillions of stars that can either form in isolation, like spiral galaxies, or can form as the result of multiple galaxies merging together, like ellipticals. Now yes, there are other types of galaxies, like irregular galaxies or the very rare ring galaxies. These are both thought to be the result of a complicated gravitational interaction or merger, and many irregulars may well wind up looking like ellipticals a few billion years from now. It’s pretty neat that the Universe is so large and so diverse that we can see, and yet explain and understand so many of the different things it does!

An amazing video on Evolution and Intelligent Design Fri, 25 Jan 2008 05:58:21 +0000 ethan Evolution, creationism, and intelligent design are words that many people have extremely strong opinions about. Regardless of how you feel about why the laws of nature are what they are, which have evidently allowed us to exist, the evidence for the validity of the theory of evolution with one major mechanism being natural selection is absolutely overwhelming. That said, this is often very hard to communicate to people, especially those with strong biases against what they perceive as the implications of evolution, how evolution works, and why the case for it is so compelling.

Thankfully, there is a person calling him/herself cdk007 making youtube videos like this one to explain how evolution works, and why arguments against it are invalid, with dauntingly demonstrative examples:

The explanation basically boils down to, regardless of how life started, once you have even the simplest life in place that reproduces, mutates, and is subject to natural selection, you will get evolution. While reproduction and mutation are random (with far more variation occurring in sexual reproduction over asexual reproduction), natural selection is not random. The fact that certain traits are selected causes events that would be exceedingly improbable at random to occur all the time.

This video is excellent, and there are many others (the Bad Astronomer likes this one); I recommend them to anyone who is looking for simple, compelling examples of how this complicated biological process works. In fact, the only explanations that I’ve ever found easier to understand were watching Episode II of Carl Sagan’s Cosmos series and watching the off-Broadway play Trumpery, a fascinating play about the scientific and personal struggles of Charles Darwin (and I think Michael Cristofer deserves to be showered with accolades for his performance as Darwin).