Title: Bigger Than the Motor Car
Written By: Aaron
Castdate: 060607
Rating: [OF] Office Friendly


DRAFT SCRIPT

	(music sample: "Squirt" by Fluke)
     	Pamela: Bigger than the motor car?
	Travis: Maybe it's an SUV.
	Pamela: I sense a theme forming. We've been doing shows about big things lately.
	Travis: Is there anything *small* in astronomy?
	Pamela: True, but today we're going to talk about really big things. Astronomically big. Huge. Gigantic. Bigger than the Da Vinci Code.
	Travis: And our story is true.
	Pamela: Well, as true as anything in astronomy can be.
	Travis: Meaning?
	Pamela: Meaning astronomy is based on a lot of indirect evidence. We can't exactly grow a star in a petri dish and watch how it behaves can we?
	Travis: Isn't that the whole premise behind the Olsen twins?
	Pamela: Exactly. People watch Entertainment Tonight and read magazines so they think they know the twins. But in reality, we're only seeing an approximation of them. It's a tiny window of who they are that has been heavily filtered through the glare of publicists, writers, directors, agents, producers, parents, Internet chat rooms, etc.
	Travis: So all we see is their surface and through that we infer that they must be shallow, spoiled and vapid.
	Pamela: We don't have to be so mean about it.
	Travis: But the point I'm making is that they may not be so bad after all. We are making huge assumptions of substance based on relatively little evidence.
	Pamela: Just like in astronomy. We take a remarkably little bit of information gleaned almost exclusively from the passive acquisition of light photons and determine such grand things as to how the Universe was formed.
	Travis: Through the last 53 episodes of Slacker Astronomy we have reported on many cool discoveries. We especially like to emphasise results that aren't covered by the mass media yet involve pretty clever methods of discovery. It's really amazing we know so much about the Universe as we do based on such little evidence, and that is largely due to the creativity and cleverness of researchers.
	Pamela: But we need to be reminded that there is much more that we don't know. And these are very tiny baby steps indeed. This week's story puts that into perspective.
	Travis: Right now our best guess puts the age of the Universe at 13.7 billion years. It is believed we can theoretically see as far back as 300,000 years after that. Beyond that all we can see is the cosmic microwave background, which can be thought of as the leftover glow from the Big Bang.
	Pamela: The Universe is expanding. Unlike our wasteline, it's not the edge that is expanding but rather the entire thing. Every little bit is expanding, and at a faster and faster rate. So the *size* of the Universe is actually greater than 13.7 billion years. There are lots of guesses at exactly how big it is right now, but no one knows for sure.
	Travis: No one knows why it is expanding faster and faster. But to keep from sounding stupid, astronomers and physicists came up with a cool name for that big question mark. They call it dark energy. You can illustrate dark energy as a collective shrug of the shoulders.
	Pamela: It is one of the largest questions facing astronomy- and indeed Mankind. Around 70 percent of the Universe is made up of this dark energy. Which means over 2/3rds of the Universe is completely unseen to us. We're clueless about it.
	Travis: The race is on to figure it out and the group that does it first will likely have one of the key discoveries of the 21st century, if not all time.
	Pamela: I hope we aren't getting your hopes up. We aren't going to talk about that discovery today. It's currently still being kept under wraps by the Illuminati. What we do have, though, is a hint, courtesy of outer space. 
	Travis: Using the Sloan Digital Sky Survey, astronomers have mapped out a HUGE chunk of the Universe. That have charted the locations of 600,000 galaxies in a 3-D cube 5.3 billion light years on a side, that's about a third of the way to the edge of the observable Universe. 
	Pamela: What they found are giant structures made up of galaxies that look similar in shape to structures seen in the cosmic microwave background. That means that the little wiggles in the microwave background create 300,000 years after the big bang has a relationship with the location of these galaxies, which exist about 10 billion years later.
	Travis: This link is a crutial test for dark energy. David Schlegel, a coauthor of the paper announcing this in a major astronomical journal...
	Pamela: And linked to in the show notes on our site..
	Travis: ...said in a press release quote - astronomers are falling over themselves to measure the precise length of these waves - unquote in the background. 
	Pamela: It's really a silly quote. When you see astronomers falling over themselves it is usually because they are clumsy or drunk. Not because of worry over waves in microwave radiation. Very few astronomers even understand the microwave background, much less worry about it. 
	Travis: But we can look past that because this is a neat result that took an awful lot of hard work. They plotted the distance to the galaxies by looking at their color. Since they are so far away, these usually bright blue galaxies looked quite red due to cosmological redshit. Basically their photons are stretched by the expansion of the Universe we talked about earlier. This makes them lose energy and become red. 
	Pamela: Usually astronomers do this through looking at spectra of galaxies. But spectra is hard! And also requires large telescopes. So they used spectra of a small sampling of the galaxies to find out the distances associated with different levels of redness. Then they compared the redness of the other galaxies to this ladder to get their distance. 
	Travis: It only provides a fuzzy answer, but when dealing with sizes on this large of a scale, fuzzy is all you need. 
	Pamela: So thanks to this hard work, we can link structures in the Universe only 5 billion years old with structures 13.4 billion years old, which means that dark energy was around during those time periods too. For dark energy is the reason those original fluctuations in the microwave background made it into the large galaxies structures we see today.
	Travis: Just remember a key thing in all of this. It sounds like we know what dark energy is. We don't. So we know there is a link out there, but we don't know exactly what the link is. Don't let someone at a party try to impress you when they drop the big dark energy bomb in on a conversation. They know nothing!
	Pamela: What parties do you go to where they discuss dark energy?
	Travis: Mostly MIT frat parties. When we aren't talking about how unrealistic Independance Day was or how to build a real Tardis, we dish on the energy. 
	Pamela: Sounds like fun.
	Travis: Don't blame me if you aren't invited.
	Pamela (pouting): I won't.
	Travis: Fine.
	Pamela: I didn't want to go your stupid parties anyway.
	Travis: Good.
	Pamela:  
	Travis: Next one is next Friday, want to go?
	Pamela: I'm there.
	Travis: Thanks for listening to ano
	Pamela: Thanks for listening to another edition of Slacker Astronomy. Show notes and past shows are available at slackerastronomy.org. 
	Travis: We also have a new chit chat show up with results from our listener location poll on the SA Extra feed.
	Pamela: For our author Aaron, he's Travis and I'm Pamela. Thanks for listening.
	Travis: This has been Slacker Astronomy, a podcast for fun, for you for the voices in our heads.