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Showing posts from January, 2008

A Test for SETI

I am a big fan of SETI, the search for extraterrestrial intelligence. If you don't know much about the SETI project, then take a look at seti.org. Buy some stuff there too so that you can support their mission, which is to find some proof that advanced life exists outside of Planet Earth.

How do we know that SETI is really doing the right thing, though? Can you possibly expect to detect any signal at all from 5 light years away using a planetary network of telescopes? One would think not because a radio wave gets wider (dispersion) as it travels farther. As it disperses, its energy dampens, and eventually the incident energy is slow low that it can not be detected above the background noise. Essentially, the noise we hear in the cosmic background, is made up of widely dispersed radio waves that have been bouncing around for billions of earth years.

Is there a way to test out the SETI thesis and make some use of their telescope network? Well, if you're a fan of the Pioneer space …

Time, Time, There is no Time.

I often wonder about time and what it really means. Some people think you can travel through time, as if it has some corporeal properties. I don't think this is so.

First off, all of our time measurements are based upon physical phenomena. A second of time is an arc second of planet movement. This is the equivalent of the Earth moving 1 arc second through it revolution about its axis. A year, keeping with the physical analogies, is just one revolution about the Sun. The Earth also moves about 139 miles per second through Space. Its movement in the galaxy is rotational, so those 139 miles are along a curved path. So really the Earth follows a curly path through Space as it travels through time.

Why is this important, you ask? Well, imagine that you can travel through time, like HG Wells would like you to think. Say you go back in time 1 second. In 1 second, the Earth has moved 139 miles from its original location, and it has moved 1 arc second about its axis. Where would you be?

If yo…