Archives for March, 2008

The Cosmic Background Radiation

This was the third and final piece of the puzzle that led to the acceptance of the Big Bang and the rejection of all alternatives: the discovery of the background radiation left over from the Big Bang. The “leading theory” before this was discovered was the Steady-State theory. Sure, they knew of Hubble Expansion. But…

The Abundance of Light Elements

This is the second key prediction of the Big Bang: the Universe was, before any stars formed, made up of about 75% Hydrogen and 25% Helium, and much less than 1% of all other elements combined. How does the Big Bang predict this, and how to we observe it? Well, remember we said the Universe…

The Hubble Expansion of the Universe

This is the first of the key predictions of the Big Bang theory, that everything in the Universe will expand according to Hubble’s Law, or that the speed that other galaxies recede from us is proportional to their distance from us. Let’s jump into the details of why the Big Bang predicts it, and how…

Did It All Start With A Bang?

Here’s a really fundamental question, and yet one that I think that most people don’t know the answer to: How do we know that the Big Bang is the right theory of the origin of the Universe? There are a bunch of alternative theories out there, after all, like Plasma Cosmology, the Steady-State Theory, and…

Weekend Diversion: Rainbows!

Starts with a bang reader Zrinka asks us how rainbows work, and that’s a great question for the weekend, since I’m driving up to Portland, OR right now. (The desert is lousy for rainbows when it doesn’t rain!) So you’ve seen something like this before, although maybe yours isn’t as famous as Galen Rowell‘s: So…

Happy March 14th, or 3.14…

Happy Pi Day! Even the BBC has a nice article on this one. Maybe someday, the US will, too. And yes, it’s nerdy, I know, but what’s frightening is that I actually have the first line of that image memorized somehow…

Inflation’s Problems and Alternatives

This month’s issue of Physics Today has an interesting article by Robert Brandenberger of McGill University, entitled Alternatives to Cosmological Inflation. As a refresher, cosmological inflation is the theory that sets up the Big Bang: it takes whatever was in the Universe prior to inflation and expands it away, leaving you with a Universe that…

Say Goodbye to Virgo…

Aaah, the Virgo cluster. A huge cluster of hundreds of galaxies, and our closest large neighbor in the Universe. People have known for a long time that although Virgo is still redshifting away from us, it isn’t quite as fast as we would expect from the Hubble expansion rate of the Universe. Does this mean…

The Universe is Accelerating?

Sure, there’s dark energy, but what does that really mean? First off, there’s the bizarre phenomenon we see: very distant objects appear dimmer than we expect in a Universe filled with just matter and space. This supernova (above) should appear much brighter for how distant it is, based on what we know about supernova. This…

Afraid of the Dark?

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…