29 March 2009

Can The Universe Expand Faster Than Light?- Apparently Yes!

Posted by Dan Satterfield

When it comes to NASA Satellites, Hubble is the star of the show. The Mars probes have gotten plenty of interest lately, but compared to Hubble, they are a flash in the pan (Wonder where that saying comes from-photography I suspect). No doubt about it, Hubble has been fantastic, and the Space Shuttle is scheduled to do one last repair mission on it in a few months.

My favourite picture, in all Astronomy, is the Hubble Deep Field. Imagine taking the most complex telescope ever built, and pointing it at an empty patch of sky. Open the shutter, and wait for days, and days. Then close it and develop the image! It’s very similar to taking a long exposure picture with a digital camera at night. You can show the whole landscape in starlight alone, if you make the exposure long enough.

The deep field image is below. Those stars are not suns like our sun. They are GALAXIES. Each containing countless billions of suns. They are all very far away. At the edge of the visible universe.

An Image from the edge of time itself.

An Image from the edge of time itself.

Astronomers and Cosmologist now think that our Universe is so big as to be incomprehensible. Let me explain, the best I can. If I get this wrong a local Astronomer will correct me. I live in Huntsville Alabama, and Marshall Space Flight Center is nearby. A friend down the street works on Chandra (More on that in a moment). So if I make a mistake, I WILL HEAR ABOUT IT! …and learn something new too!

Oh yes, how big is the Universe.

Let’s talk age first.

13,700 Million years. (Give or take a few million)

Now think hard about this for a second. Say there is a star, one trillion light years away from Earth. The light from this sun is headed toward us at the speed of light. It will take one trillion years for it to get here.


It Ain’t here yet!

We cannot see it!

WE CANNOT SEE ANYTHING FURTHER THAN 13,700 MILLION LIGHT YEARS AWAY! (Actually because space itself is expanding we can see about 45,000 million light years but this gets complicated. So ignore what I just wrote. It’s purpose was to save me having to write sheepishly back to an Astronomer and say “Well yes I did know that…)

Doesn’t mean there isn’t something far, far beyond, our “visible universe”  though.

The current thinking, is that at the time of the Big Bang, (13,700 million years ago) the Universe underwent INFLATION. This would mean an expansion, faster than the speed of light. (This does NOT violate relativity, according to Cosmologist Alex Filipenko of U.C. Berkely).


The Universe is still expanding, and according to the current theories, it will likely keep on expanding forever.  Eventually, every object will be too far from every other object, to be seen. A cold and dark end to it all. The speed of the expansion, is also INCREASING, and it may pass the speed of light as well. Again, this is not a violation of relativity.

Think of balloon with dots all over it. The dots are galaxies. The ballon is the universe. As the balloon is blown up the galaxies (dots) all start separating. The light traveling between the universe dots can only go at light speed. The balloon can inflate faster than this.

Don’t yell at me! I am just telling you what the Astronomers say!

So the Universe may be billions of times bigger than 13,700 million light years in every direction. There is good evidence that it is. Watch the Berkeley Astronomy lectures I wrote about in a previous post. They are riveting, and free. (I knew you would like that last part.)

So what Hubble saw was a glimpse of the edge of time. We cannot see much beyond it, but there is likely a whole lot there.

I was going to talk a bit about the Chandra X-Ray Telescope. It doesn’t get the attention of Hubble, but arguably it is more important. I will save that for a future post.



PS Pics from NASA, and Flash in the pan comes from the days of Muskets. (According to my close friend Alan in Wales, who knows all kinds of things like this off the top of his head!)