Category Archives: Science: Physics, Astronomy, etc.

True (magnetic) north

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Much of my wife’s family is Canadian, so I keep an uncommon interest in Canada — for an American. This is to say, I think about it once a month or so, more often during hockey season. So here is a semi-interesting factoid:

The magnetic north pole, the “true north” has been moving northwest for some time, but the rate has increased over the last few decades as the picture shows. It has now left the northern Canadian islands, so Canada is no longer “The true north, strong and free.” (It seems to be strong and free). True north  is now moving northwest, toward Siberia. true magnetic north heading to Russia

Why is the galaxy stable?

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Our planet, Earth, is located in a spiral galaxy, with two arms. We’re about 30,000 light years out from the galactic center (1.8E17 miles), and based on red-shift data, our spot moves around the center at about 1,000,000,000 miles/year or 100,000 mph. This is a normal, average speed for other galaxies too. Our whole of the galaxy thus goes round every 200,000,000 years, maintaining its spiral shape as it does. Based on the age of the sun. We’ve gone around the center about 50 times so far. Based on this, there are a few obvious questions that were unknown when I was in grad school in 1976-81 and still unknown now. 

First question, why are we moving round so fast, and why are the other galaxies doing the same. Large rotation speeds should not naturally come out of random variation of the gas molecule speeds. And if it comes from different galaxies moving past one another, that just pushes the rotation source problem further out. Maxwell averaging of gas molecules should produce 2000 mph at most, given the temperatures in space. 

Another question, even more interesting: If the galaxy’s gone around about 50 times since it condensed, why are there still spiral arms? That’s an awful lot of turns for our galactic arms to retain stable; you’d expect that the outer parts of the arms would have rotated far fewer times, perhaps only once, while the inner parts would have rotated perhaps 1000 times. After a billion years, you’d expect the arms to be gone. The going explanation is that there is dark matter, matter we can’t see, but there should be a lot of dark matter, more than normal matter in fact. Where does it come from? Why don’t we see it?

After bugging astrophysicists for a few years, I’ve come to believe that many of their models (MACHOs, WIMPs) don’t make much sense. I’ve come to be able to model the distribution of dark matter on my own. Based on the stability of things, it seems clear that it is a particular distribution of light, non-interacting particles, with just the right mass to keep it as a non-rotating cloud. This is fine, as far as it goes, a version of the “WIMP theory” where WIMP stands for Weakly Interacting, Massive Particles. It turns out there is only a narrow range of size-mass for these WIMP particles that fits our rotation stability and does not mess up other galaxies. We want our galaxy rotating as a unit — can you figure out what the WIMP particle distribution is? If interested think, or ask: buxbaum@rebresearch.com

A spiral galaxy

A spiral galaxy, much like our own.

But this doesn’t mean that I now know what dark matter WIMPs are. I think I know where they are, but now we need to find the missing matter and understand it. It directly interacts with itself, but not with other matter except by gravity, and yet it came to be, so it should interact at some energy.  Also, how did it avoid becoming a spinning disc. All you need is gravity to get other things spinning in the galaxy, why not the dark matter? All the other matter ended up in a spinning disc, because of…. a galactic collision, but this stuff isn’t. The properties of this dark matter are very weird indeed. 

A current theory, and it barely justifies being called a theory, is that gravity diminishes at intra-galactic distances. That is, it works like Newton and Einstein say at planetary distances, and does so exactly to fine, fine detail. Then it works the same at inter-galactic distances, moving on galaxy relative to another using the exact same behavior, but somehow, within the galaxy, it becomes weaker. This would be a nonsense theory except that no-one has found the WIMPy particles, or massive MACHOs for that matter. 

As a challenge, see if you can calculate the distribution of dark matter that would result in our galaxy rotating as a unit. 

— Robert Buxbaum, Dec. 10, 2012. Perhaps an easier question, why doesn’t the heat of all the stars cook us?

The universe is not endless

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You may have heard that the universe is not endless, ending at a brick wall, perhaps, some 15 billion light years out. But what you may not know is that this understanding is backed by a classic proof, going back to the middle ages. What follows is that proof.

Consider an endless universe with a fairly uniform distribution of stars. In any large-enough volume of this universe we expect to find many stars, e.g. in the spherical shell between 100 and 101 trillion miles from earth. At this distance, each of these stars is close enough to see individually; the combination of them (the sum in this volumetric shell) sheds a small amount of heat on the earth. Now consider another shell, the same thickness but twice as far from us, that is between 200 and 201 trillion miles from earth. If the universe is uniform, there will be 4 times as many stars in this shell, but since these stars are twice the distance from us, each star will present us with ¼ as much heat. Now, with 4 times the stars, the total effect is to radiate as much heat to us as from the first shell.

The same argument goes for each spherical shell of this 1 trillion miles thickness: each one presents us with the same amount of heat. If the universe is infinite and uniform, we find there will be an infinite number of shells radiating this amount of heat, and therefore an infinite amount of heat bathing us. We should expect to roast from all of it. Since we have not roasted, we conclude that the universe is not an endless, uniform expanse.

Based on this proof, the universe could be uniform, but only if it’s not endless. It could end with a brick wall, as in the Hitch-hikers guide. Alternately, the universe could have an end because it’s expanding from a big bang. This latter is suggested by the observed red shift showing that stars far from us move away faster in proportion to their distance. I’d expect this to be a favored answer of creationists because a point of creation suggests a creator. Creationists hate this finding, and dismiss the data too because the observed redshift suggests creation happened 15 Billion years ago. Atheists, needless to say, hate this “Big Bang” explanation.

Book: Fractals in Nature by Mandelbrot

The mathematician Bernard B Mandelbrot noticed that much of nature has a distribution that scaled by fractional dimensional, like 2.5

Another thought, more acceptable to atheists, is that the universe is a closed, oscillating four dimensional hypersphere, where time is oscillating along with space. Einstein liked this view, but never fleshed it out, perhaps because there was no way for this expansion to bounce in, and periodically reverse time and entropy.

A fairly recent view that I like is that the universe could be fractal in distribution. (Mandelbrot). It isn’t clear how the universe got that way, or how it fits with the observed redshift, but it easily allows for a universe that isn’t endless nor possessing a clear limit, a last star as it were. It also provides a uniform/ non-uniform model of mass distribution. Besides, this matches much of nature. As it turns out to be fractal. Chaos of this sort is sort of God’s fingerprint.

For another unsolved cosmological question, consider why are there stable galactic arms, see here. Robert Buxbaum, October 22, 2012.

Why tornadoes and hurricanes lift up cars, cows, etc.

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Here’s a video I made for my nieces and any other young adults on why it is that tornadoes and hurricanes lift stuff up. It’s all centrifugal forces — the same forces that generate the low pressure zone at the center of hurricanes. The explanation is from Albert Einstein, who goes on show why it is that rivers don’t run straight; before you read any more of it, I’d suggest you first watch the video here. It’s from my Facebook page, so it should be visible.

If can’t see, you may have to friend me on Facebook, but until then the video shows a glass coffee cup with some coffee grounds and water in it. Originally, the grounds are at the bottom of the cup showing that they are heavier than the water. When I swirl the water in the cup, you’ll see that the grounds are lifted up into a heap in the center with some flowing all around in a circle — to the top surface and then to the walls of the cup. This is the same path followed by light things (papers for example) in a tornado. Cows, houses and cars that are caught up in real tornadoes get sucked in and lifted up too, but they never get to the top to be thrown outward.

The explanation for the lifting is that the upper layers of liquid swirl faster than the lower layers. As a result there is a low pressure zone above the middle of the swirl. The water (or air) moves upward into this lower pressure area and drags along with it cows, cars, houses and the like (Here’s another post on the subject of where the swirl comes from). The reason the swirl is faster above the bottom of the cup is that the cup bottom adds drag to the flow (the very bottom isn’t swirling at all). The faster rotating, upper flows have a reasonable amount of centrifugal force and thus a lower pressure in the middle of the swirl, and a higher pressure further out. The non-rotating bottom has a more uniform pressure that’s relatively higher in the middle, and relatively lower on the outside. As a result there is a secondary flow where air moves down around the outside of the flow and up in the middle. You can see this secondary flow in the video by following the lighter grounds.

Robert. E. Buxbaum. Weather is not exactly climate, but in my opinion both are cyclic and chaotic. I find there is little evidence that we can stop climate change, and suspect there is no advantage to wanting the earth colder. There was a tornado drought in 2013, and a hurricane draught too. You may not have heard of either because it’s hard to report on the storms that didn’t happen.