How Big Is the Universe?

Posted on June 27, 2011 by Bill

Billions of galaxies of stars.
This is just a very small section of sky, smaller than the diameter of the full moon as seen from earth. It looks empty and black to the unaided eye, but the Hubble Space Telescope photographed all these galaxies in it.

When I studied science in high school more than 50 years ago, we learned that astronomers estimated there were between 100 billion and 1,000 billion (one trillion) stars in our Milky Way Galaxy. They also estimated there were between 100 billion and one trillion galaxies in the known universe.

It always struck me as a little bit strange that the range of estimated stars per galaxy and the range of estimated galaxies were the same, but it’s just a coincidence with no meaning except inside my head. (Yes, coincidences are sometimes real.)

Recently, I’ve read and heard exactly the same range of numbers: 100 billion from one source, a trillion from another source, and several estimates in between for both numbers. These particular ranges of estimates have remained the same for more than half a century. Let’s be conservative and use the number 200 billion for this essay. 200 billion stars in each of 200 billion galaxies. This seems to be the single estimate I have heard most often during all these years.

How many stars total is that? It’s 200,000,000,000 times itself; or 200,000,000,000 squared. That’s 40,000,000,000,000,000,000.000, or forty billion trillion, or forty sextillion stars in the known universe. It’s an unimaginably huge number. The human mind simply cannot understand a number that large unless we illustrate it some way.

The stars of the sky have been described as “innumerable,” and they are. Not the ones you can see on a clear night. There are only a couple of thousand stars you can see with your unaided eyes at night, and that assumes you have very good eyes and a really dark place from which to look. But nobody can count all the stars in space, else we wouldn’t have to estimate.

There are about seven billion (7,000,000,000) people on earth. The United Nations actually estimates we’ll pass that number sometime this year. If we were all lined up and crowded together so that we only had one foot of space to stand in, we’d make a line 1,325,758 miles long. Long enough to stretch to the moon and back more than 2 ½ times.

But suppose we were all given extremely powerful telescopes and asked to count all the stars in the universe. If each human now alive could count a star every second, 24 hours a day with no breaks, and nobody ever counted the same star twice, it would take us 181,000 years to finish the job. That’s almost as long as our species, H. sapiens, has existed on earth.

Even that may not be the whole universe; it’s the part we can study, at least in principle. The part we call “the known universe.” If there’s more — and there probably is — it’s so far away that even the light from it could not have reached us in all the 13.7 billion years the universe has existed. There doesn’t seem to be any possible way humans will ever be able to study it directly.

The moral of this story is, the universe is huge. Really huge. Fantastically huge. It’s far, far larger than you or I can possibly imagine.

Posted in other science | Leave a comment

Pool-Playing Robot

Posted on June 14, 2011 by Bill

There has been tremendous progress in robotics recently. Here’s one that plays pool.

A robot, of course, is just a machine of any kind that is controlled by a computer. The computer is its “brain”. So it’s very significant to robotics that a computer named Watson recently beat the two all-time champion humans on Jeopardy.

It’ll take a while before they will be truly intelligent in a human sense. When it happens, I suspect the computers won’t even be digital like we use now. They may be quantum computers. Or we may even go back to the old analog computer technology before that happens. Or I may be wrong; I’ve been fooled before.

One way or another, it is bound to happen within the next few decades. We’ll have computers and robots as intelligent and dextrous as humans. If not more so. They already do far more than just play games.

What will they do for us when they’re as smart as we are? Or to us? Will they still work for us, or will they turn against us? I don’t know. It is very difficult to understand in advance how new technology will affect us. Who would have ever guessed in 1981 (when IBM made its first PC) that it would lead to Facebook and Twitter? Or even the Internet and the World Wide Web?

Posted in technology | Leave a comment

Ring Species: A Fascinating Example of Evolution

Posted on June 12, 2011 by Bill


This is not the only example of a “ring species” by any means. A more familiar one to many people is the encitina, a California salamander. It probably originated in Oregon around ten million years ago, and migrated south through the redwood forests of northern California to the northern end of California’s great central valley. There they split into two groups, one of which migrated south along each side of the valley.

Those on the east side developed a strategy of camouflage, blending in with their surroundings to hide from predators. By the time they reached the southern tip of the valley, their descendents had become black with big tan splotches.

Those on the west side, toward the Pacific ocean, followed a strategy of mimicry, looking more and more like a particular, poisonous newt living in the same area. When they reached the southern tip of the valley, their descendents there had become a solid, glossy, brownish-orange color. Very different from their cousins 0n the other side.

All down the eastern side of the valley, the encitinas change gradually from place to place, but they keep on mating with their neighbors and producing viable offspring. That is, their offspring live normal salamander lives and produce offspring of their own, keeping the species going.

Down the western side of the valley, the same process occurs. The encitinas change gradually from place to place, but they keep on mating with their neighbors and producing viable offspring to keep the species going. This pattern changes only when the cousins from the two sides of the valley meet again at the southern end.

The solid, glossy, brownish-orange salamanders from the west side of the valley often mate with the gaudy black ones with the big tan splotches from the east side; but their offspring are usually mis-shapen and off-color, so they neither blend into the environment nor fool predators into thinking they are dangerous. The hybrids are not suited (or “adapted”) to the environment, and seldom live long enough to reproduce. Therefore, they are not “viable.”

The changes from generation to generation, and from one place to the next, were so small that they continued to interbreed on both sides of the valley as they migrated south; yet they split from one species in the north into two species in the south over the course of a few million years and a few hundred miles.

These ring species are wonderful, current examples of micro-evolution becoming macro-evolution just by adding one tiny change to another tiny change until they add up to big changes.

Comments:

1. Lest I be accused of “picking and choosing my facts,” I need to comment here that encitinas crossed the valley and interbred with those on the other side at least a time or two. Biologists can tell that by studying their offspring. But the valley was so inhospitable to them that it seldom happened. For all practical purposes, they evolved as I have described above. The point is that their descendents at the southern tip of the valley meet the definition of separate species. Many species are formed in exactly this way.

2. Phrases like “developed a strategy of camouflage” are not meant to imply that they did it intentionally. Of course they did not. Random mutations set the stage for this “development” and the non-random process of natural selection primarily brought it about.

Posted in critical thinking, evolution | Leave a comment