So what makes scientists doubt Velikovsky's views? They have
a long list of reasons why such a scenerio was not possible.
A few of the more important ones are:
The temperature of Venus. Actually, both sides in this controversy
point to this as evidence for their claims. When Velikovsky
first published his ideas the temperature on the surface of
Venus was not known. As Frank Drake of the National Radio
Astronomy Observatory wrote, "We would have expected a temperature
of only slightly greater than that of Earth..." Velikovsky
had predicted Venus, after its close encounter with Earth,
Mars and the Sun, would have a much higher than expected temperature.
Indeed it was discovered that the surface temperature was
750 degrees Kelvin. Hot enough to melt lead.
Carl Sagan, one of Velikovsky's most ardent critics, argued
that if Venus had been ejected out of Jupiter, the required
amount of energy would have heated Venus so much the planet/comet
would have vaporized. And even if somehow the planet had managed
to survive the ejection the temperature, even thousands of
years later, claimed Sagan, would have been much greater than
those found today. Sagan also argued that if Venus had been
on an extremely eccentric orbit as Velikovsky suggests, it
would be highly unlikely that it could have changed its orbit
so radically in the few thousand years to the nearly circular
orbit that the planet enjoys today.
Velikovsky didn't seem to be concerned with the problems
his theory generated for physicists. He himself said, "the
ancient traditions are our best guide to the appearance and
arrangement of the earliest remembered solar system, not some
fancy computer's retrocalculations based upon current understanding
of astronomical principles."
However, other scientific disciplines don't seem to bear
out Velikovsky's ideas, either. Geologists who have cored
into the world's icepacks and ocean bottoms have not found
signs of the deposits Venus made upon Earth as the Earth passed
through the planet/comet's tail (In fact Venus is much too
massive with too strong a gravity to ever have had a visible
tail as Velikovsky claims).
Venusian geology doesn't seem to support a young Venus, either.
Radar studies of the planet's surface show a landscape saturated
with craters. The overlapping edges of these craters show
they are impact craters instead of volcanic. The high number
of them show that the Venusian surface is very old. There
are just too many of them to have accumulated in just the
past 3,500 years. Even in the realm of anthropology there
seems to be problems with the Velikovsky theories.
According to Worlds in Collision Venus did not exist before
about 1,500 B.C.. In his book Velikovsky says that neither
the Hindus or the Babylonians recorded the planet Venus. However
Peter Huber, from the Edgennossische Technische Hochschule,
Zurich, reports that in Cuneiform texts stetching as far back
as 3,000 B.C., Venus is mentioned as the star connected with
the rising and setting sun. Clear evidence that it occupied
an orbit in between the Earth and the sun as it does today.
Also in records from 1580 to 1560 B.C. observations were made
of Venus that clearly puts it in an orbit identical with the
planet's current orbit.
So are Velikovsky's ideas that events in the solar system
might affect life on Earth worthless? No, not at all. While
Velikovsky is apparently wrong about a Venus that wanders
through the solar system in historical times, he may have
in some small way stimulated scientific thinking on the stability
of the solar system. Isaac Asimov, who referred to Velikovsky's
theories as a type of "exoheresy" wrote: "For one thing Velikfovskianism,
and indeed, any exoheretical view that becomes prominent enough
to force itself on science, acts to puncture scientific complacency-and
that is good. An exoheresy may cause scientists to bestir
themselves for the purpose of reexamining the bases of their
beliefs, even if only to gather firm and logical reasons for
the rejection of the exoheresy-and that is good too. An exoheresy
may cause scientific activity which, in a serendipitous fashion,
may uncover something worthwhile that has nothing to do with
the exoheresy-and that is very good, if it happens."
When Velikovsky first wrote Worlds in Collision, many scientists
rejected it not only because of reasoned arguments, but because
the idea that the solar system could change or that events
in space could have a profound effect on life on Earth was
unsettling. Since that time science has accepted that asteroid
impacts have led to massive extinctions on Earth (just ask
Even the orbits of the planets no longer seem set in stone.
In an article in the September 1999 edition of Scientific
American, Renu Malhotra makes a case that the planets Saturn,
Uranus and Neptune may have expanded their orbits since the
beginning of the solar system, while Jupiter's orbit has shrunk.
He also argues that interactions between Neptune and the planet
Pluto have caused the smaller planet to shift from a near
circular orbit to a more eccentric one that is on a plane
inclined from the rest of the planets.
Will we one day find evidence of events in the solar system
that might explain what Velikovsky observed in some ancient
texts? Perhaps so. But if we are to take any explanation seriously,
we must bring the full weight of several scientific disciplines
like anthropology, physics and geology, to bear the problem
and get their results to agree.