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Old 02-15-2013, 05:53 PM   #121
W*GS
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A small summary of some of the material in "Broca's Brain" that devastates Velikovsky.

What Carl Sagan has to say about Velikovsky

Quote:
What Carl Sagan has to say about Velikovsky
Glenn Schuett
I thought those with firing synapses might like to hear what Carl Sagan has to say about Velikovsky. This comes from his book _Broca's Brain_, 1976, ISBN 0-345-33689-5.

This is incomplete (so much to debunk!), Sagan uses more than 50 pages destroying Velikovsky's hypothesis. Here are some of the highlights.

PROBLEM I - THE EJECTION OF VENUS BY JUPITER

Velikovsky says: Venus was ejected from Jupiter as a comet.

Sagan says: To escape from Jupiter, the comet must have a kinetic energy of 1/2mv^2, where m=cometary mass and v=escape velocity of Jupiter. This equals about 60 km/sec. At least 10% of this kinetic energy will go into heating the comet.

The minimum kinetic energy per unit mass is 1/2v^2 = 1.3 x 10^13 ergs per gram.

The heat portion of the kinetic energy is more than 2.5 x 10^12 erg/gram. Rock melts at about 4 x 10^9 erg/gram. Thus, any event that ejected a comet or planet from Jupiter would melt rock (or organic compounds or ices).

Another problem is the escape velocity from the Sun's gravity (at the distance of Jupiter it is about 20 km/sec). Thus, if a comet leaves Jupiter at velocities less than 60 km/sec it will fall back to Jupiter; if greater than about [(20)^2 + (60)^2]^1/2 = 63 km/sec it will escape from the solar system. There is only a narrow and therefore unlikely range of velocities consistent with V's hypothesis.

Further, the mass of Venus is more than 5 x 10^27 grams. The total kinetic energy required to propel Venus from Jupiter's escape velocity is about 10^41 ergs, which is equivalent to all the energy radiated by the Sun in one year and 100 million times more powerful than the largest solar flare ever observed. V wants us to believe that an ejection event occured on Jupiter that was vastly more powerful than anything on the Sun.

PROBLEM II - REPEATED COLLISIONS AMONG THE EARTH, VENUS AND MARS

Velikovsky says: "That a comet may strike our planet is not very probable, but the idea is not absurd" (page 40 English edition).

Sagan says: [Sagan devotes several pages in the appendix calculating orbits, gravitational attractions, velocities etc.; too long and too many Greek symbols to reproduce here]

In short - V says that the planets have collided a total of 5 or 6 times among themselves. The odds of this happening (ignoring other problems with his hypothesis) is almost 100 billion trillion to 1 for five collisions and about one trillion quadrillion to 1 for 6 collisions.

PROBLEM III - THE EARTH'S ROTATION

This concerns the story in Joshua about the earth standing still for a day. V is vague about the mechanism that is supposed to have breaked the Earth's rotation. Sagan acknowledges that the Earth could slow down over a 24 hour period without it melting or people flying off, but the temperature generated, especially near sea level, would be about 240 degrees Kelvin, well above the boiling point of water. He shows his math in Appendix 2.

V also fails to account for the Earth starting up it's rotation again, which it can't do itself due to the law of conservation of angular momentum.

Sagan also discusses tidal gravitational and magnetic forces that would be necessary to stop the Earth's rotation.

But wait! there's more!

This is but 3 of 10 "major scientific flaws in Velikovsky's agrument" that Sagan outlines. Plus he briefly goes into several more.

Go read the book. It's good.
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