Awesome Astronomy


Cosmology

What is cosmology and why is it awesome?

Cosmology is basically the study of the universe: what it looks like, where it came from, how it behaves, and what we can learn from it about the future and past.

What does the universe look like? Well, no one knows for sure whether or not the universe has a definitive shape or even if our universe is alone or one of many. But we have been able to map surprisingly large amounts of the universe.

Map of the Universe

One thing we are pretty sure about is that the universe is expanding. Many people think that this means that the galaxies themselves are expanding, but the size of the objects in the universe are not effected, just their positions relative to one another. This animation shows what the universe would look like expanding if it were round. The white spirals represent galaxies.

Hubble’s Law tells us that the age of the Universe should be somewhere around 14 billion years old… but where did it come from and why is it here?

One theory to explain this is the Big Bang.It’s the theory that basically one day our Universe, which was at that moment in time an infinitely dense point of mass, suddenly underwent a reaction so violent it caused such massive expansion that, well, 14 billion years later, the Universe is pretty big.

There’s still a lot of debate as to what that first event was that caused this expansion, but astronomers have been able to describe a surprising amount of what they believe happened immediately following the Big Bang. This handy timeline describes the evolution of the Universe quite efficently:

Evolution of the Universe

But where did that mass come from? No one’s sure. Some scientists hypothesize we might have begun at the center of a black hole. Another pretty awesome theory I heard the other day (but which I haven’t validated yet, so don’t quote me) is that our Universe might actually be stuck between two massive black holes that are pulling us apart. Disturbing, but also pretty awesome.

Another question that arises as a result of our conception of the Big Bang is why is everything made of matter and not antimatter?

You’ve probably heard of antimatter thanks to Dan Brown and CERN, but where antimatter came from and what the implications it can have for astronomy are still unclear.

Antimatter is exactly like matter, except made out of electrons that are oppositely charged. This means that if you saw a far off galaxy you would have no way of knowing if it was made of matter or antimatter because they look exactly the same. Both where created out of the same energy split in half, which is why when they come in contact they annihilate each other and become energy again. When they where created some slight tip in the scales allowed matter to overpower antimatter when composing our universe. However, this does not mean all the antimatter is just gone. It may have formed another antimatter universe parallel to our own. Pretty awesome when you think about it.

Well, I guess that is all for now.

Next time I will wrap up with some generally awesome facts and videos about astronomy.

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General Relativity

General Relativity is… well, awesome. The number one reason is because after you really understand General Relativity you’re like, no way is that real, that’s something they just took out of a science fiction movie! But it’s not. It is real science.

I’m not going to attempt to give you an explanation of General Relativity because I’ll just confuse you, but I’d recommend taking a minute and watching this clip from Elegant Universe, it’s a little cheesy, but a really clear explanation with good computer modeling. Fast forward to about minute 3 and a half if you want to skip the Newtonian part, it’s interesting but not neccessary:

So, what sort of implications for awesomeness does General Relativity present us out there in the Universe?

Lets begin with my favorite, black holes.

You see General Relativity basically explains why black holes exist. If ordinary matter can never travel as fast as light, and if not even light can escape from a collapsing star, nothing else can either.

Black holes create a warp in spacetime, this leads to lots of interesting different effects the closer you get to one.

If you were on a spaceship watching another spaceship fall into a black hole as the ship approached the black hole you’d begin to see it slow down. It would take the ship an infinite amount of time to reach the black hole because it is so dense (and because time slows the closer you get to a dense mass). This means even as the ship is being ripped into bits you would see it hang there forever (although you’d need infrared goggles to see the redshift.) Time would essentially become an asymptotic function, if you’re calculus-ly inclined.

Black holes are so incredibly strong that they would rip the ship into atoms and then possibly even rip those atoms apart. If someone was on the ship falling into the black hole they would not see a slowing of time, and of course they’d be quickly disintegrated.

Here’s a video model of what it might look like to fall into a black hole:

This video shows what it would look like to see something fall into a black hole:

So what’s on the other side of a black hole?

That’s an excellent question. No one’s one hundred percent sure, but some astrophysicists think that rotating black holes could lead to wormholes.

Wormholes, as Einstein and Rosen described them, would happen almost instantaneously and then collapse, making them almost impossible to travel through. The wormhole modeled in this video is called an Einstein-Rosen bridge, which would theoretically form a bridge between two points in our universe. Not all of the narration in this video is accurate but the model’s good:

It’s also thought that wormholes could possibly form links between our universe and other parallel universes. This video’s longer but it’s interesting if you’ve got the time. They talk about theories for how you’d keep the wormholes open:

What other phenomena occur out there in space as a result of General Relativity? Well, one aspect of the nature of light that many people aren’t aware of is how long it takes light from other stars and galaxies to reach us and how this affects the way we see the Universe. For instance light from the Andromeda Galaxy, the closest galaxy to us, has to travel 6 million light years to reach us! That means that we’re seeing that galaxy right now as it existed 6 million years ago! Isn’t that awesome.

The Andromeda Galaxy

The same would be true of a person in Andromeda viewing the Milky Way. Astronomers aren’t even sure exactly what all of the Universe looks like because of this. It’s thought that Quasars are actually visual remnants of forming galaxies that no longer exist as Quasars but which we still see that way because it is taking so long for the light to reach our eyes.

Quasar

Well, I guess that’s enough about General Relativity for today. But before I go we should talk about what we learned about modeling today. First of all modeling is pretty useful for talking about theoretical concepts like gravity waves and wormholes that you can’t create in a lab to test. It can also come in handy because of the fact that our ability to observe portions of the universe is limited by the time it takes light to reach our eyes. Models can help us to fill in the gaps between what we see and what we hypothesize is happening.

I didn’t talk much about Gravity Waves, but if you’re interested you should check out the LIGO expirement website. It’s very informative and they have some excellent astronomical models.

Next time I’ll be talking about Cosmology!

I’ll leave you with this as an appetizer:


Black Holes!! (a.k.a.This is My first post!)

For my first post I’m going to spend a little time talking about Black Holes, mostly because I think they’re insanely awesome. I’m doing this blog for my astronomy class and the theme is mostly supposed to be modeling of astronomical events, so I’ll begin with a pretty cool little video model of a black hole pulling the material off of a star (#9 on the original page). Sadly it’s not in a format compatible for me to post directly to the blog, but here is a handy link to the page, which has other video models you can view from the Chandra mission:

http://chandra.harvard.edu/resources/animations/blackholes.html

still from the page:

Black Hole Absorbing a Star

Why is this a useful model? Mostly because we’ve never really been able to observe firsthand anything being absorbed by a blackhole. Partially because of technology and partially because it takes soooo long to happen. Models are particularly nifty in astronomy for that reason, because it usually takes things sssooooo long to happen out there in space (like thousands or millions or even billions of years) models are a way for us to observe processes and make speculations on their outcomes.

I also suggest checking out video # 10 on the Chandra page which models a blackhole in an eliptical galaxy

Black Hole in an Eliptical Galaxy

If you weren’t already aware of it, pretty much every galaxy out there in space has a black hole at the center, even ours. What makes black holes so powerful and dense?

Black holes are quantum singularities. Essentially what happens (and this is a very simplified version of it) is that when massive stars finally finish all their fusing and can’t fuse anymore they collapse in on themselves with such force that all of that matter gets compacted down into an infinitely dense point. You can also think of it as a hole or warp in spacetime, which probably actually doesn’t help much.

I was unable to find a good model of a black hole forming (although they’re probably out there somewhere) but this is a pretty cool animation of blackholes that have already formed galaxies┬ácolliding (again something that would take millions of years to happen in real time):

Black holes can really only be seen in their relation to other matter (like stuff orbiting it or being pulled in). This is a very exagerrated image of what a black hole might look like in a Large Magellanic Cloud:

Illustration of a Black Hole

So models are useful for yet another reason: we can’t really see black holes so well with the naked eye, or even with┬ámany telescopes for that matter.

Black holes are all around amazing!

If you want to know anymore about the basics of black holes I’ll do the unthinkable and refer you to Wikipedia: http://en.wikipedia.org/wiki/Black_hole

That’s all for the basics on modeling black holes for now. Next time I’ll be talking about Time and General Relativity (and probably more black holes)!