Posted by
michael
on from the start-on-this-planet dept.
tanveer1979 writes "Space.com is carrying a very informative article about the "Arecibo Diaries" i.e. the search for Life outside. It explains all about the Arecibo telescope, the false alarms and all else."
SETI is a Black Hole
by
PhysicsGenius
·
· Score: 4, Interesting
As much as I'd like to believe in alien intelligence (and I do!) I
can't hold still for mathematical abuses such as the infamous Drake
Equation. To take one example:
One of the assumptions that Drake built in is that a signal of
sufficient strength can travel arbitrarily far. This simply isn't so.
Einstein himself showed nearly a century ago that spacetime is bent
back on itself in the presence of gravitational force. For an object
the size of a planet the effect is minor (except for the inhabitants,
ha ha) but even something as relatively puny as our sun can deflect a
beam of light measurably.
The point of this is that a signal will only propagate outwards until
the total mass behind it exceeds a critical value (the location of
this is called the "event horizon" in an analogy to black holes). At
that point its deflection will equal more than 90 degrees...i.e. it
will not go any farther from its point of origin.
Sending signals outward is useless unless we expect to find
intelligence within the tiny (universally speaking) sphere defined by
this event horizon. And, via symmetry, we can prove that listening
for signals from other solar systems is useless for the same reason.
The money spent on SETI would do better on something mathematically
possible, like NASA's attempts to create an anti-gravity device.
Slashdot Mirror
One of the assumptions that Drake built in is that a signal of sufficient strength can travel arbitrarily far. This simply isn't so. Einstein himself showed nearly a century ago that spacetime is bent back on itself in the presence of gravitational force. For an object the size of a planet the effect is minor (except for the inhabitants, ha ha) but even something as relatively puny as our sun can deflect a beam of light measurably.
The point of this is that a signal will only propagate outwards until the total mass behind it exceeds a critical value (the location of this is called the "event horizon" in an analogy to black holes). At that point its deflection will equal more than 90 degrees...i.e. it will not go any farther from its point of origin.
Sending signals outward is useless unless we expect to find intelligence within the tiny (universally speaking) sphere defined by this event horizon. And, via symmetry, we can prove that listening for signals from other solar systems is useless for the same reason. The money spent on SETI would do better on something mathematically possible, like NASA's attempts to create an anti-gravity device.