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If the Internet represents an ever-changing map to human culture, human art, and human thought, the universe itself represents a map to the mind of its creator. The process of understanding the universe -- the physical reality that surrounds us -- is called science. I find certain areas of science absolutely fascinating....
Earth-based (or earth-orbit-based) exploration of the universe using telescopes is both the oldest and farthest-reaching of mankind's attempts to learn about the universe he lives in. I also find it the most fascinating part of mankind's exploration of the universe. This is why.
Any observation of the universe that relies on light or any other form of electromagnetic radiation, as telescopes do, is exploration of time as well as space. This is because light and all other forms of electromagnetic radiation travel at a finite speed -- approximately 300,000 kilometers/second (or 186,000 miles/second) in a vacuum. This speed varies when travelling through an atmosphere or other substance, but when light travels across space, it rarely encounters anything that can slow it down much or for long. In my calculations below, I assume that the speed of light is constant.
Distances between any two places on earth are small enough that light, or radio, transmission appears instantaneous. It isn't, of course -- there is always a time interval, even between when you switch on a light at home and the light from the bulb reaches your eyes. We don't perceive a time gap, though, because it is so tiny, and on earth we don't usually need to consider this time gap. We assume that what we see is what is happening at that time.
When you start looking at other planets within our solar system, though, you must allow for the time it takes light to travel from its origin to you on earth. It takes light about eight and a half minutes to travel the 150 million kilometers (or 93 million miles) from the sun to the Earth. It takes that same light approximately another four and a quarter minutes to travel the 78 million kilometers (or 49 million miles) from Earth to Mars, and another half hour or so to travel the 550 million kilometers (or 340 million miles) from Mars to Jupiter.
Even within our solar system, we cannot see what is happening on the sun or another planet at a particular time. We can only see what happened a few minutes earlier.
Most of what earth-based telescopes examine is much, much farther away than the sun or Mars, though. The nearest star to earth, Alpha Proxima, is approximately 4 trillion kilometers (or 2.5 trillion miles) from us. It takes light over four years to travel from Alpha Proxima to the earth, which means that when we look at Alpha Proxima through a telescope, what we see is what was happening there over four years ago.
Even this is a tiny distance compared to the distances to most of what we see in the night sky. It takes the light from stars at the center of our galaxy, the Milky Way, about twenty eight thousand years to reach us. In other words, what we see through our telescopes is what was happening during the Ice Age on earth. The human race had not yet learned to smelt metal. There were no pyramids -- they would not be built for another twenty thousand years. The earliest forms of written language would not be developed for another twenty thousand years. The ancient cave paintings in Europe and northern Africa, those astoundingly beautiful earliest works of art, would not be painted for another fifteen thousand years.
And even this vast distance is tiny compared to the distances between galaxies. Light from Andromeda, the nearest galaxy to our own Milky Way, must travel over two million years to reach us. In other words, when we look at Andromeda through our telescopes, we see what was happening during the later Pliocene epoch on earth. The earliest ancestors of the human race, Homo Australopithecus, lived in Africa and the Middle East. They walked on two legs, but had only 1/3 of the brain capacity of modern humans. They used only the most primitive of tools. Descendents of theirs would finally discover a use for fire only after another million and a half years passed.
And even this distance, in space and time, pales compared to that between us and the most distant galaxies and astronomical objects we've been able to see so far. Some of them are so distant that it takes light over 10 billion years to reach us. When we look at these distant galaxies, we see what was happening long before earth formed, when our solar system was still an undifferentiated mass of hot gas that would not cool and start forming planets for another several billion years.
Light from the most distant of these most distant astronomical objects, huge and energetic masses we call quasars, has been travelling to us for around 12 to 14 billion years. That is approximately how old astronomers believe the universe is -- most estimate that the big bang took place between 10 and 20 billion years ago. So when we look at the light from these most distant objects, we are seeing part of our own universe shortly after its birth.
Here are web sites for several astronomical projects and telescopes.
Earth is home, and so far is the only planet human beings have experienced directly. Despite that, we still haven't seen parts of our own planet. We still do not understand many features of this planet that keep us alive, and yet humanity's technological development in the last two hundred years and the population explosion have made us capable, for the first time, of upsetting the ecological balance in which we evolved.. It is unlikely humanity will survive to explore the rest of space if we don't understand and take care of what we already have....
Physics fascinates me more than any other major area of science because it focuses on the extreme edges of known reality. And physicists are constantly expanding those boundaries.
In the last hundred years, the human race has gone from being essentially planet-bound to taking its first, tentative steps off the earth. In 1959, the spacecraft Sputnik 1 became the first man-made object to leave earth's atmosphere. In 1961, Yuri Gagarin of the former Soviet Union became the first human being to leave earth's atmosphere. These Russian efforts were quickly followed by a crash American space program that, in the following decade, sent unmanned spacecraft as far as Jupiter and put a man on the moon. In the following decades, unmanned spacecraft explored all the planets in the solar system. One unmanned space ship, Voyager, has even left our solar system entirely.
Voyager was not designed to last this long or travel this far, however. It will probably be at least another generation before the human race begins to send space ships intended to explore outside of our solar system. In addition, after its early success putting men on the moon, NASA has retreated to low earth orbit, building the reusable space shuttle and limiting manned space flight to it and a series of low earth orbit space stations.
This is less because of technological limitations than political limitations. Space exploration is expensive, and its benefits aren't obvious to all people. Not everyone sees the value in exploration for its own sake, or in figuring out how the universe is built and what makes it work just to know, and not necessarily for some other reason. Those who do see the value in knowledge for its own sake usually find it difficult to explain to others why they do because, for them, it's obvious and needs no explanation.
It's as if an art lover had to explain his love for Michangelo's David to someone who saw sculpture as nothing but shaped rocks.
Fortunately for Michelangelo, in a dictatorship or oligarchy (as Florence and most of Italy were when he lived there), you have to convince only one person, or a small group of people, of the value of what you are doing to get your funding. In a democracy, you must convince enough of your fellow citizens that they will support you, and keep them convinced so that they continue to support you through elections, and through recessions. While I infinitely prefer to live in a democracy, and for many reasons, democracies are slower and less efficient in getting anything done, and require a much more from their citizens.
I don't work in the space program, but I am convinced that space exploration is worth doing, and I want to do my small part to convince you of the same.
In addition, I want to encourage privately-funded, non-governmental space flight efforts. On June 21, 2004, Scaled Composites of Mojave, California became the first such private company to put a man into space. It did it again on September 29, 2004. On October 5, 2004 Scaled repeated this feat for the third time, winning the Ansari X-Prize. The X-Prize was a ten million dollar prize offered to the first company to build a spacecraft, fly three people into space, and then repeat the flight within two weeks using the same spacecraft.
Scaled did it in five days. I admit it -- I'm impressed. :)
Below are a link to pages I wrote about the June 21 space flight. (I was in the crowd at the airport in Mojave, California.) Beneath my pages are links to pages that a friend, Jeff Chan, and other space nuts put up after they attended one or more of the SpaceShipOne flights. Beneath those links are links to the home pages for the X-Prize Foundation, Scaled Composites, and other X- Prize competitors that I feel bear watching.
Finally, one of the great questions.... Are we alone in the universe or not? I'm convinced beyond convincing that we are not alone, but science doesn't concern itself with angels. It does, however, concern itself with whether there is other intelligent non-terrestrial biological life -- living beings of a type similar enough to humans that communication and mutual recognition is possible. Here are links to the web sites of some groups looking for intelligent exterrestrial beings.
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Last modified on Thursday, October 23, 2008 at 8:40 AM PDT.