Have you lain awake at night lately pondering the deep, unsolved questions of the universe? No I don’t mean how to pay this month’s rent or achieve world peace or make sure you don’t miss the bus again. No, I mean the real questions about the universe. Like these. If, like me, you have, here’s help with three of them.
- How is it that light has a speed limit?
When light traveling at c enters a refracting medium such as water or glass, its velocity is slowed. Now visible light is a range of multiple frequencies, it’s colors, from infrared to ultraviolet, and each is slowed to a different degree. Newton showed us this. In the process, the light gives up some of its energy, so when it leaves that medium, it leaves at a different intensity. However, the instant it leaves that medium, it resumes its original velocity, c. This is because that velocity is not a function of its energy level, its intensity, but is a function of the medium carrying it just as the speed of sound varies as its medium varies. This is true because the refracting medium, say, glass or water, is itself a structure of the same substance as that of the light, a higher energy density concentration of the medium, and the interaction of light with those concentrations results in a measure of damping, even cancelling out some of the frequencies of the light.
We must consider that the universe is, like an ocean, home to many disparate, more or less diffuse phenomena, like currents, layers, varying frequencies and amplitudes; but also containing unique, organized, and coherent, more or less stable entities such as stars, galaxies, clusters, planets, rocks, even humans, all created out of the same substance, the energy of the cosmos. Some of these entities are of such dense concentrations of energy that they absorb all of the energy of the impinging light. We say that these are opaque. Some have a partial damping effect. They are called translucent. And some offer little or no barriers to light. Each gives up some energy in this passage, usually converted to a lower form like heat, some perhaps to cause other, structural changes as was shown in Einstein’s Nobel winning discovery, the photoelectric effect, although his proposed mechanism may be questioned..
- What is dark energy?
If there existed in the universe no individual, unique entities, that is, no stars, no planets, not even any intergalactic dust, then all of the universe would be 100% “dark energy.” And it would be pretty dark! What?? you say. How do we know this?
Well, because two Bell Systems engineers, looking for something else, found it. And lo, we can detect it in all directions, even when we point our detectors toward apparently empty regions of the sky. When this phenomenon was first detected, it was misinterpreted, probably because we were in the throes of “big bang” theories and the experts immediately grabbed this new finding for their own and dubbed it the “echo of the big bang.” That meant hanging everything on the assumption of a great “something from nothing” theory and using any new discovery as evidence for it. But what if there was no “big bang”? What if there were only gradual populating of the cosmos with tiny energy concentrations that gradually grew into proto-stars, then galaxies, and ultimately into what we see today? After all, in the absence of any “big bang” we had all the time in the world, not just 13.7 billion years, didn’t we? This makes sense in another way as well. It means that what we see today is the same as what we would have seen millions of years ago, instead of the theory that everything happened all at once, a singularity never to be repeated, and that there will never be evidence of what came before.
The simple answer, and may Sir William of Occam rest easy in his grave, is that what the seekers of mystery in our midst choose to call dark (because unknown?) energy, is the energy that makes up the entire limitless cosmos and is the medium from which all things are made and the medium that gives light and all other radiation its speed limit, the medium that Wilson and Penzias discovered, the medium that was then called the CMBR.
- What is “dark matter”?
When somebody, probably many somebodies, calculated in an idle moment how much mass the universe actually contains. then subtracted that part which is observable from our little observatory here on earth, they came up with a large remainder, some 95%. Then they calculated the amount that was somehow affecting the observable mass, came up with about 27% and called that “dark matter.” The rest of the unknown, missing mass they called “dark energy,” (68%), is explained above.
But, to understand what dark matter really is, let’s go back about 100 years, to Einstein’s Theory of General Relativity. When Albert, bless him, sought to describe gravity in a new way, he came up with an invention called “spacetime”, a four-dimensional entity in which all observable masses existed. Then he said that the presence of a mass in that medium caused it to be distorted, and the example he used was that of a heavy ball lying on an elastic sheet, causing a depression in the sheet which made passing objects tend to fall toward the massive ball. This was a nice simple way to describe what appeared to be happening but, like Newton’s model before him, it didn’t explain what gravity was, just how it worked.
Now let’s substitute something real for Einstein’s “spacetime,” which he made up by joining two concepts neither of which actually exist as objects in nature, let’s substitute our concept of a cosmos made up of an electromagnetic field of energy, something we can show actually exists. We also know that high concentrations of energy affect the region in which they appear, creating what we call a field. In our model of the universe, that “field” is actually a distortion of the cosmic field. We also know that the intensity of that effect is highest nearest the central phenomenon and falls off at a fixed rate as one moves away from it. So what we have near a high energy concentration, say a star or a planet, is a distortion of the cosmos that raises its energy level to a detectable effect on nearby objects. This is how we detect “dark matter” is it not? by its effects. So, it’s all part of the same complex. Dark matter is energy raised to a detectable level, but not yet to the level where it becomes visible. So it stays dark, but we know it’s there. Wow! And we can see how light is distorted when it passes near a star, because it’s passing through a high energy density region. And when an object passes near a star, its speed slows and it falls toward that star, just as Einstein’s distorted sheet drew it in.
I know there are other pressing questions, but at least now you may be able to sleep a little better, along with the comfort that someone is out there looking for the answers. Patience. And good night.