Tuesday, July 9, 2013

Let there be light! ... and some other stuff too

Whew, that last blog post by fart-sniffer was pretty much a downer!  Sure, it started off just fine and dandy with a cool description of our region of the universe and a neat movie to boot.  But near the end of his post, bird-brain goes on to talk about how very insignificant we are compared to the vastness of the universe.  That we are orbiting an ordinary star in the outskirts of an ordinary galaxy in an unremarkable part of what is a truly vast universe.  Ugh, he truly is a buzz kill!

However, despite how small I felt after reading this, I could not help but think that it is in fact true.  We truly are a ridiculously small spec in space (and time) in the grand scheme of things.  This fact is both disturbing and humbling to me at the same time.

But there is something special about us, something that continues to give me goosebumps.  Overly-proportioned-torso-man touched upon it in his post, but I am writing a bit more here to elaborate.  We are the only species on this planet to develop the capability of figuring out our place in the universe.  Perhaps there are other alien species out there that have evolved to the same level of intelligence, but we have not yet encountered them if they do exist.  Instead, to-date, we are the only known form of life capable of looking out at the stars and figuring out what happened from the Big Bang (no, not the TV show, but the event nearly 14 billion years ago that created the universe) until now.

What is more amazing to me though is that, despite some exceptions to which I will return shortly, the ONLY source of information that astronomers have to figure out ALL that we know of the universe and how we came to be is light.  In an earlier post, I discussed how most of the universe is composed of dark matter and dark energy that do not emit any sort of light at all.  Yet, despite this, we have determined a vast amount of information from light.  Sure, light in this context refers to more than just the light we can see with our eyes; I am also referring to the other parts of the electromagnetic spectrum.  Radio waves, for example, are a form of light.  So are X-rays.  They are electromagnetic waves, but each type of wave has a different energy.  So, radio waves have much lower energy than visible light waves (like the color blue), and these visible waves have much lower energy than X-rays.

But from these various forms of light, we can determine SO very much about the universe.  We observe the stars and by seeing how much of one type of light there is relative to another (e.g., how blue the star is vs. red), we can figure out the composition of the star, it's age, etc..  We can view the light of distant galaxies and based upon something known as redshift, we can figure out how far away these galaxies are from our own galaxy.

These are just two examples, but my point is that nearly everything we know about the universe arrives to us in the form of light.  So, let there be light!

But wait!  I mentioned earlier that there were some exceptions.  Indeed, I would be remiss to exclude other methods and sources that complement what astronomers determine from light.  Theoretical work in particular (which is what I do, and yes, it's better than X-ray astronomy, Background Dominated!!!) helps us to understand what we see in the night sky by constructing models to explain observed behaviors.  These models can be written in the form of equations or run on big-ass supercomputers (my personal favorite!).

There are also some laboratory experiments carried out to understand physics that occurs in the cosmos, missions sent to planets and moons and asteroids in our solar system, and a few other pathways towards gathering information.

But let me return to the information arriving at Earth from the universe itself.  Like I said over and over again here, light is the main source of information.  But there are also other things that the cosmos throws at us.  Cosmic rays are very high energy particles that originate from space and bombard our atmosphere.  Sometimes, they even reach the surface.

Neutrinos are very low mass particles that move at extremely high speeds and barely interact with anything.  There are also a LOT of them; billions and billions of them pass through each of us every second -- don't worry, they are harmless.  Despite their vastly large numbers, they are quite hard to detect, though not impossible (see here).

Finally, I just want to finish with another type of "wave radiation" that astronomers are currently quite excited about -- gravitational waves.  In short, these waves are fluctuations in the fabric of space-time itself.  Theory predicts that these waves will result from events like the merging of two black holes.  We have not yet detected such waves because it turns out they are very very very hard to detect.  But astronomers are currently working on improved detectors to observe these waves.

So, what's the punchline?  Yes, our place in the universe is quite insignificant as feather-fingers points out, but our knowledge of the universe is amazingly vast given that most of the information we know about it comes from light (and yes, some other stuff too...).

Gravitational waves radiating from merging black holes.
And the part that I always hate: this is an artist's conception.  But wouldn't it be cool if it weren't?!
Credit:T. Carnahan (NASA GSFC)

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