Category Archives: science

cosmological constant

The energy density of empty space is called the cosmological constant. It accounts for the force that causes the expansion of the universe. Its value is approximately 10^-29 g/cm^3. This is an incredibly tiny positive number. They call this stuff dark energy.

As the universe expands, the density of ordinary matter like stars and rocks decreases because new matter is not magically appearing to fill in the space. The incredible thing about the cosmological constant is that the energy density of vacuum does not decrease as the universe expands with time. If this does not surprise you, then let me explore this a little deeper.

mass = density * volume

If the universe is expanding, then the volume is growing larger with time. If the density remains constant, then this would mean that the mass-energy of the universe is ever increasing.

Reconcile that with the First Law of Thermodynamics.

In any process, the total energy of the universe remains the same.

Are we to believe that the universe itself violates the First Law of Thermodynamics?

expanding universe

(follow up to 2003/07/27)

Scientists observe the following phenomena:

  1. Based on observations of supernovae, galaxies are known to be moving farther away from each other in the universe.
  2. The farther away the galaxy is from us, the greater the red shift in the light from that galaxy. Similar to the Doppler effect, the faster the galaxy is moving away from us, the greater the wavelengths of light are shifted towards the red side of the electromagnetic spectrum. This means that the farther away the galaxy is from us, the faster it is moving away from us.
  3. The farther away the galaxy is from us, the more time it takes for light to travel, before it arrives for us to observe. Therefore, the greater the distance travelled, the farther back into history we are observing.

Based on these observations, scientists theorize that the universe has been expanding. Extrapolating back in time, the theory projects that in the distant past (13.7 billion years ago +/- 200 million years), the universe must have been very compact and incredibly hot and dense. This is the Big Bang theory.

They also conclude that the expansion of the universe has been accelerating.

I don’t understand how they can arrive at that conclusion.

If at greater distances, we observe greater red shift, this means that farther back in time we observe higher velocity of expansion. In other words, as time moves forward, the velocity of expansion decreases. Wouldn’t elementary physics tell us that the expansion of the universe is actually decelerating – NOT increasing in velocity?

more galactic hurricanes

In an act of incredible hubris, I actually emailed my previous idea to Professor Lawrence Krauss, the author of Quintessence. Upon some reflection, I wonder just how idiotic my idea would appear to someone, who actually knows something about what he’s talking about. Let’s see if I get a response, and how small I can be made to feel. (In truth, the entire feeling thing is not applicable to me, so don’t worry. I am kidding about having any worries about such ridiculous things.)

hypothesis: galactic hurricanes

As I peruse hurricane alley on space.com and then look at isabel on cnn, I cannot help but notice the visual similarity between hurricanes and spiral galaxies.

It leads me to wonder if there are correlations between the angular momentum of galaxies and their locations within the universe. And if there are, whether this can tell us something about the nature of the dark matter that dominates the universe, binds stars into galaxies, and binds galaxies into clusters. The motion of stars revolving in a galaxy already tells us how much dark matter there is, and how that mass is distributed in the neighborhood of a galaxy. Perhaps the galactic rotations of all the galaxies in a cluster can give us a better topological map of the mass distribution for the cluster. I wonder if cosmologists have considered this phenomenon, because I haven’t seen any mention of such a study before. I doubt it’s an original idea, because it seems like such an obvious thing to observe.

Notice that hurricanes, tornadoes, and the water falling down the drain spiral in a counter-clockwise motion in the northern hemisphere. They spiral in the opposite direction in the southern hemisphere. Hence, there is a correlation between angular momentum and position for these phenomena on the surface of the earth. I am suggesting that if we were to observe such a correlation in galaxies, it could tell us something about the geometry of space due to the gravity of the mass in that vicinity. e.g., these galaxies in the “north” are all rotating counter-clockwise, while those galaxies in the “south” are all rotating clockwise, so this suggests the cluster behaves as one big spherical rotating mass! Could there also be patterns to observe at even larger scales?

Perhaps the question was asked and observations showed no definite patterns due to naive interpretations. Imagine if the earth were transparent, and only hurricanes were visible to distant observers on Mars. In the north, they would see storms rotating counter-clockwise on the near-side of the earth, and storms rotating clockwise on the far-side of the earth. Without very accurate distance measurements, their observations would not reveal anything of note. I suspect this is precisely the situation we are faced with when looking at distant galactic clusters.

red shift

As we look into the distance, deep into the past, towards the big bang, it is mind boggling how unintuitive it seems. If you look far enough into the distance, you should be able to see the earliest moments after the big bang. This would be the cosmic background radiation, as quarks condensed into protons and neutrons.

What is more confusing to me is the interpretation of the evidence that suggests the universe is expanding at an increasing rate. This conclusion is based on observing red shifts. The farther an object is from us, the faster it appears to be moving away. Unless I’m misunderstanding something, doesn’t this tell us that the expansion of the universe is actually slowing down?

If distance is proportional to time, then wouldn’t an accelerating expansion demonstrate higher differences in velocity (red shift) for objects nearer to us. Since they are near, we see them as they were relatively recently as compared to far away objects. If the rate of expansion is accelerating, then observations of more recent events should show higher velocities than observations of events in the more distant past. On the other hand, if the velocity of distant objects is higher than the velocity of nearer objects, then shouldn’t it be logical to conclude that expansion is slowing rather than quickening?

quintessence

I have begun to read Quintessence. It starts out rather dull. I am hoping that it picks up soon. Unlike End of Time, the author’s style is not provocative; he seems very methodical — though I’m only at the beginning, which contains all the introductory context.

Dark matter and dark energy have become a favorite topic for my curiosity. What better subject can there be to help stimulate the imagination? Observations suggest that there is something incredibly important throughout the universe that dominates its behavior, and no one knows what it is. These things cannot be sensed directly. They are completely different than anything we know today.

Free your mind.

Many people are unable to free their minds of what they know to be true, so that they can evaluate ideas from a different perspective. It is debilitating to be a rigid thinker. They are weak at evaluating alternative mental models, because they cannot apply their limited imagination in constructing such models.

What kind of image does the expanding universe invoke? Does your mind picture the universe itself as a ball growing larger, its boundaries stretching outwards? Or does it picture, as an observer within the universe itself, all of the galaxies moving away from eachother? Or does it picture a static universe without any notion of time or motion, and the expansion is merely a path in configuration space? Does it recognize the false notion of being an outside observer, while allowing this fiction to be imagined?

How do you picture the void of empty space? Is it a three (or higher) dimensional grid? Is it curved by the massive objects? Is it absolutely nothing at all, except for the void between things that actually exist? Or is it ethereal, filled with virtual particles that flash in and out of existence beyond our ability to perceive?

At many points in history, fundamental questions as simple as “what is space?” and “what is time?” have been asked and answered. Still we do not know the true answers; we only have intuitive notions based on teachings that have been socialized. We go through school learning mostly by rote the laws of the universe, such as those related to motion, momentum, and energy — notions that depend on understanding space and time. We are taught to treat space and time as intuitively obvious, because they are understood ostensibly. Yet, there may not be a single human being that has ever truly understood the nature of space and time — if those ideas have any correspondence to reality at all, and the jury is definitely out on that one. Despite this dilemma, the vast majority of students finish school with confidence that they know a great deal about space, time, motion, and many other important things. They don’t have an appreciation for the context of their knowledge — the limited scope of understanding that is encapsulated. They are taught the current state of understanding, which is good enough for most practical purposes in ordinary life. They are lies, or reasonable facsimiles of the truth, good enough to get you through most days without going too awry.

Just as the earth is not flat (though from a person’s viewpoint, it may appear that way), and the sun does not orbit the earth (though from a person’s viewpoint, it may appear that way), these ideas were once at the pinnacle of human knowledge, only to be invalidated later. We accept theories like general relativity and quantum mechanics because there isn’t yet any better explanation. They can be applied to good effect as a practical matter for a limited set of problems. But let us not forget that the accuracy of current theories has much room for improvement.

timeless

I am sitting here in a Boeing 737 on the tarmac, as maintenance personnel check over the aircraft to determine why some indicator lights are showing a problem. What has been occupying my mind is the first few pages I’ve read of The End of Time – The Next Revolution in Physics by Julian Barbour. He suggests that there is in reality no such thing as time. It is merely a figment of our misinterpretation of the facts, which result from the limited scope of our personal experiences. This idea is very provocative, because it goes against intuition and it seemingly contradicts everything we know to be true. There is something extremely violent and destructive in this notion. Just the possibility of setting fire to something that we hold as fundamental is exciting.

This is very serendipitous. My life’s work seems to revolve around creative thinking. One of my fundamental responsibilities is to think outside the box to solve problems that are beyond the normal capacity of others. I must imagine what lies outside of common knowledge, and embrace possibilities that may be seemingly absurd or false, in order to discover that something out there is in fact precisely what must be true (or brought into reality). Thinking outside the box requires that in fact there is no box. Or perhaps that all those poor souls, who thought they were in the box, were actually floating outside a bubble. Or something much more bizarre.

today’s lessons

I received a copy of The Pleasure of Finding Things Out. I’m only 86 pages into the book, and I’m already loving Richard Feynman. He was a truly brilliant man.

No doubt Feynman felt responsible in part for the development of the atomic bomb. His first hand account of his time in the Manhattan Project is gripping and hilarious. This man’s efficacy and his light-hearted perspective are inspirational.

And the one thing that Von Neumann gave me was an idea that he had which was interesting. That you don’t have to be responsible for the world that you’re in, and so I have developed a very strong sense of social irresponsibility as a result of Von Neumann’s advice. It’s made me a very happy man since.

Feynman reminisced about his father’s influence on his childhood learning. Here is a notable passage that demonstrates how well his father’s views align with my own.

there was a picture of the Pope and everybody bowing in front of him. […] Why are they all bowing to him? Only because of his name and his position, because of his uniform, not because of something special he did, or his honor, or something like that.

Recognitions of symbol versus substance catch my attention.

Like any advanced thinker, Feynman’s ability manifested in a diverse set of ideas.

Because of the success of science, there is, I think, a kind of pseudoscience. Social science is an example […] We get experts on everything that sound like they’re sort of scientific experts. They’re not scientific, they sit at a typewriter and they make up something like, oh, food grown with, er, fertilizer that’s organic is better for you than food grown with fertilizer that’s inorganic – may be true, may not be true, but it hasn’t been demonstrated one way or the other. But they’ll sit there on the typewriter and make up all this stuff as if it’s science and then become an expert on foods, organic foods and so on. There’s all kinds of myths and pseudoscience all over the place.

I may be quite wrong, maybe they know all these things, but I don’t think I’m wrong. You see, I have the advantage of having found out how hard it is to to get to really know something, how careful you have to be about checking the experiments, how easy it is to make mistakes and fool yourself. I know what it means to know something, and therefore I see how they get their information and I can’t believe that they know it, they haven’t done the work necessary.

That is priceless.