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Science Over the EdgeA Roundup of Strange Science for the MonthApplet credit: Ed Hobbs
January 2007 |
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In the News:
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What's New at the Museum:
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Ask the Curator:
Actually there are whole galaxies (collections of billions of stars) moving away from us faster than the speed of light. As amazing as it sounds, this does not really contradict Einstein's theories. Let's start at the beginning. If you stand along a road and listen to a car zoom by you will hear the pitch of the sound it makes suddenly drop as it passes you. This is because the pitch of the sound is based on how many sound waves per second reach your ear. When the car is traveling toward you, the waves come by you faster than normal because the speed of the car is added to their normal speed. The sound becomes lower when the car passes by because then the speed of the car moving away increases the time it takes each wave to pass you by. This is called the Doppler Effect. The Doppler Effect works with sound, radio (you may have heard of Doppler radar) and light waves. As a lighted object moves away from you the light is pushed to a lower frequency (toward the red end of the spectrum therefore scientists say it is "red shifted"). Using this red shift is one important way of measuring how fast an object is moving away from us in space. The famed astronomer, Edwin Hubble, also noticed that, in astronomical terms, the speed an object moving away from us will also tell us how distant the object is from us. Why? Because apparently the universe is undergoing an expansion and had been for the last 13.7 billion years starting with the "Big Bang." The best way to imagine this expansion is to picture a balloon with two marks drawn on it. As the balloon inflates the marks are pushed farther apart. Now replace those marks with galaxies and the balloon with the universe. As the universe expands it carries the galaxies father apart. In fact, if the galaxies are far enough separated, they will move apart at a speed faster than the speed of light. This can be confirmed by looking and seeing how much a galaxy's light has been "red shifted." Einstein's probation on faster-than-light travel isn't broken; however, because the galaxies were not accelerated to those speeds like a rocket ship, they are simply being carried along by the inflation of the universe. In fact, if you were sitting in that distant galaxy it would seem to you like you weren't moving at all (Our galaxy would seem to be the one speeding away). Many galaxies are in this position relative to ours. In fact, any galaxy father away than a distance of 4,200 mega parsecs would be moving away from us at the speed of light or faster. Eventually, over billions of years, as these galaxies get far enough away they will first appear to freeze, then fade, as the light from them can no longer out run the movement of their galaxy away from us.
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| In History:
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In the Sky:
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Observed:
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LGM: Science over the Edge ArchivesLGM Archive 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007 Copyright Lee Krystek 2007. All Rights Reserved. |