Dark Matter, Part 3. Synthesis.

The Scientist by James White

Part 1

Part 2

Okay, in Part 1 I noted that dark matter is not directly observable. The reason scientists know that it's there is because something is affecting objects in our space that are directly observable, in ways and for reasons that are understood—gravity draws together, particles get excited when energy is added to the system, spatial expansion pulls apart, etc.—but there isn't anything visible to account for these effects. Dark matter is the name given to these intangible but very real sources of interaction.

If a star is acting like gravity is pulling it a particular direction but there is nothing where we expect there to be the thing that is pulling on it, the star is still being pulled. We just can't see what's doing it. Now, black holes have been offered as a potential culprit here, but the amount of interaction, the sheer volume of interaction that is otherwise unaccounted for would require a truly unfathomable number of black holes, which would probably also lead to a less densely-starred visible universe. Plus, you actually can detect black holes, and they haven't in relation to this, so there's that.

Now, imagine an analogy. Think about driving a car. When you are driving, you are going (most of the time, unless you are a very unusual driver) toward your destination. You cannot simultaneously go away from your destination, right? Now think about driving on a two-lane road. A car is coming from the other direction. As you pass each other, you hear the car, feel the buffet of wind, and its gone, away behind you, heading the direction you came from as you head the direction they came from. You had a moment of interaction, but it was tangible, and even though they were going the other direction along that axis, that car affected yours in a very real way. Had it been a semi, the effect would have lasted longer. If it had been a train (what are you doing driving there, you lunatic?), the effect would have lasted a lot longer. If you were also in a train, longer and more pronounced still! And again, what the hell?

What if?

What if dark matter is perfectly normal matter, that is moving the other direction in time? It still has mass, not anti-mass or something, perfectly normal three-dimensional mass that is simply moving backward through time. Of course, from the dark matter's point of view it would appear that it is moving "forward" in time, just as the oncoming car is moving "toward" the place you left, but relative to us observers on this side of the temporal road, it is moving backward through time. Our matter would act upon dark matter in the same way—not directly observable from that side, but the effects of gravity and such are very visible.

The idea opens up some interesting possibilities. We will likely one day get to a place where we can peek at that dark matter—we may have already, at the Large Hadron Collider, though it may or may not have been interpreted so—and if we can peek, we may eventually be able to jump between the cars, hitch a ride the other direction for a ways or forever.

Roads? Where we're going, we don't need roads.

Dark Matter, Part 2. The nature of time.

Here's Part 1

Now, here is another concept relevant to this broader discussion. It may be familiar to some of (the two of) you, but here goes. We are used to thinking of time as its own thing. We even split it off from space to reference space-time or spacetime. The problem is, time is not separate but related. Time is a dimension, the 4th dimension. Time is the fourth dimension of space, not a separate-but-related thing. To whit:

• The first dimension is length. It goes in two directions. For this discussion, left and right.
• The second dimension is depth. It goes in two directions. Toward and away.
• The third dimension is height. It goes in two directions. Up and down.
• The fourth dimension is time. It goes in two directions. Forward and backward.

Edit: This incredible video explains this fairly well. Rob Bryanton is apparently a genius, and while I first saw his "Imagining The Tenth Dimension" video  quite a long time ago, I just discovered this video (and his channel--omg am I going to spend a lot of time there) while adding links to this already-written post. I feel kind of like an idiot. Well, not the first time, and certainly not the last. 

See, this is the thing that has taken me thirty years to finally understand. Sue me, I'm a slow learner. Measuring velocity, for example, can be stated as "miles per hour." What is really measured, though, is simply the shift in spatial location. That's it. Since time is only a dimension of normal space, stating "88 miles an hour" is actually describing a simple locational shift. At 88 mph, you will go this far along the x, y, z axes AS WELL AS along the axis of time (for which I will snag the variable q for this discussion). Without the axis of time, you would instantly teleport from one place to another—you would simply blip 88 miles (or whatever), without traveling along any of the axes of space. To borrow an explanation, you would simply jump over the intervening distance to instantly arrive at that particular location. The inclusion of time as another measure of space is the only way to allow travel—actual movement—along the other 3 axes as well. *

Something else to consider: even if something does not move along the x, y or z axes, it still moves along the q axis unless its existence is literally instantaneous. To be fair, it is unlikely that there are many things in the universe that are not moving at all, but things that are not moving in relation to one another are an accessible example. The stupid thermometer that doesn't work out on my front porch, for example. It doesn't move (x, y, z) in relation to the porch, the house, the street or the town, but it, as well as the other things not moving x, y, z, are still moving along q together. Anyway, side note.

Everything in our experience, everything in our existence, has been continually moving in one direction along q. We are continually, constantly moving forward through time. Effect follows cause. Consequence succeeds action. Just like, if you drop something, it falls down, so too do we continually "fall" forward through time. If gravity pulls down, then what is the mechanism for this direction of travel along time? I have suspicions, but only that, so I won’t go into it here. The point is that we move in one direction through time, but as a dimension, time has two directions. This is the entire principle behind the idea of time travel, after all, either speeding up travel forward or allowing travel backward.

Next up, part 3, where I try to bring it together.

* The Time Machine (1960) had a fair explanation of the concept of time as a dimension. It was still a bit thin, and the movie itself is pretty awful, but it tried to explain the idea that time is a measure of space more directly than Doc Brown did. It also explains a couple interesting homages/easter eggs in the Back to the Future movies, but I digress.

 

Dark Matter, Part 1. Gravity and stuff.

Image courtesy of CFHTLenS

There is a growing interest in the concept of dark matter and dark energy in astrophysics. Initially, I was skeptical, as it sounded too…well, fantastic for a real concept in science. It sounded like they were just making shit up at this point instead of simply saying "we have no idea."

Of course, as the years have passed, scientists' understanding and communication regarding dark matterand energy have increased dramatically, and now I get it. Not the math, mind you—I'm an anthropologist, not an astrophysicist, and there are reasons for that. I get the broader picture, a sense of the physics involved.

Dark matter and dark energy (which, like matter and energy, are merely two states of the same thing, and which I will abbreviate here on out by just referring to dark matter, though I mean both) are not directly observable, hence their monikers. A quick explanation:

Stars are incredibly massive objects. Even our sun, which is fairly modest in size, is unfathomably huge, and the stuff it is made out of is remarkably dense. All the naturally-occurring elements we know of were created, through fusion, in the hearts of stars, and those elements, and probably a lot we've never encountered, are still inside those stars. This is why the planets, even huge, far-flung ones like the gas giants, stay in orbit rather than slinging off into interstellar space, never to be seen again— the planets' own mass and inertia keep attempting a straight line of movement, but the star is so massive that its gravity counteracts the planets' tendency to shoot off in a straight line, and keeps them perpetually falling in toward it. Think about it a minute: Earth is a gigantic chunk of iron that is 93,000,000 miles away from the sun, sailing along at 67,000 mph (108,000 kph), and the sun is still so massive that the earth keeps falling towards it, and has for billions of years. Just. Think. About. That.

Objects this massive have a measurable effect on other objects that are even many light-years away. Stars and clouds of loose interstellar dust and debris all tug and pull towards one another. Inertia, stellar winds, ejecta, and the expansion of space push them apart. Collections of objects this massive—from star nurseries to full-blown galaxies—have an even more pronounced effect through the aggregation of all this mass and energy in relatively close proximity.

All of this can be measured, particularly now, since Hubble and Kepler were launched into orbit, eliminating atmospheric interference. I don't know all of the details (again, anthropologist), but I know that some of it involves measuring subtle shifts in emissive energies (which, if I'm not mistaken, serve as something of a fingerprint for galaxies, if not individual stars, though maybe those too), and some of it involves watching how the light from a more distant star or galaxy is bent ("lensed") as it passes by nearer objects. The effects of gravity are also observable by the interactions between masses in space—Star Trek: Generations played heavily with this very idea.

Tomorrow, part 2, where I discuss time.