Darkness, Imprisoning Me

I've shown versions of this graph several times, but it never ceases to amaze me. To wit: Everything you see, touch, could see or touch, every star in the night sky, every galaxy snapped by Hubble, every bit of matter that exists in the Universe (according to current theory) only represents around 4% of the total mass of the Universe. Most of it, as you see above, is Dark Energy, and the rest, Dark Matter.

For a long time, I was skeptical - what the hell is "Dark Anything"? And there's some reason to be skeptical (of everything, really) of Dark Energy, since no one really has much of an idea what it is - this energy is the force causing the Universe to expand. Which is very much proven. What's causing it to expand is thrown into the catch all category of "Dark Energy", which does translate to: Not sure yet, still working on it.

I suspect (and correct me if I'm wrong) the phrase "Dark Energy" came from the prior use of the word when it comes to "Dark Matter", which is a far more tangible concept, though of course still with much to discover. No one's directly observed Dark Matter, and no one's really sure what it's made of - though there are many strong theories - but its effects seem clearly proven. To wit: There's something out there we cannot see that has a strong gravitational effect.

Now, this bothered me still, until I saw it explained as such: Dark Matter is simply "matter" that does not interact with the Electromagnetic Force. A-Ha! That makes sense to me. As I've written before, everything you experience as "solid" is really the effects of electromagnetic fields colliding with each other. Your atoms never touch the atoms in the person's hand you're shaking, but rather, the electromagnetic fields of your atoms interact with the electromagnetic fields in the atoms in the other person's hands. So, if there is a form of matter out there that does not interact at all with the Electromagnetic Force, well, we wouldn't be able to see it in any spectrum, since all radiation - X-rays, microwaves, radio waves, infrared, etc - are manifestations of the Electromagnetic Force. It would be "Dark". 

But just because it doesn't interact with the Electromagnetic Force does not mean it cannot interact with the other forces - Gravity, the Strong Nuclear Force (binding), and the Weak Nuclear Force (decaying). In this case, Gravity.

As with the protoplanetary disks discussed below, gravity drives almost everything in our reality - the creation of the stars, the galaxies, everything it seems. It's all pervasive, or apparently so. And thus, we have the case of Dark Matter, where there are gravitational effects happening that cannot be explained by the "normal" matter that can be detected with our telescopes. And as the graph above indicates, this Dark Matter far out-masses "normal" matter. And so our reality looks like this:

Our little existence of radiation swimming in a vast shell of Dark Matter. Again, this should seem familiar, but if not, stay tuned!

There's been one astronomical event that has helped this theory of Dark Matter along greatly, and that's a special little galactic cluster now called the "Bullet Cluster". Gander:

This pic is showing two clusters of galaxies that have passed through each other some time ago, each heading in a different direction. The red shows X-rays of the gas in each cluster (it's very hot), the blue is a representation of the galactic lensing going on right beside it. Galactic lensing is a phenomena whereby objects in the far distance are distorted due to high gravity between you, the viewer, and the actual object - think of looking at a face through a glass of water. To wit: The gas was clearly affected by this collision - you can see the "bow shock" on the right side of the image, but the mass of gravity wasn't effected at all - it passed right through with nary a ripple, as so:

Detailed analysis of the gravity in this region has revealed a gravitational topographic map that shows the majority of gravity here is not located where we see the actual matter, but rather, off to each side:

Just like a topo map of Earth, the closer the lines get together, the higher the gravity. And thus we have, to date, the most concrete evidence of Dark Matter - don't get me wrong, it's still damn inconclusive, and it would be wise to be moderately skeptical - but how else would you explain so much gravity occurring where there's no obvious matter? And why its shape barely changed while the galaxies themselves got distorted? Dark Matter works for me, for now. I hope it does for you too!

In conclusion, I hope this meandering post gives you a glimpse of the mysteries that await us. For all our learning, for all our vast powers, we've just begun to scratch the surface of this, our miraculous reality. But we're gaining ground fast. Stay tuned.