This article says the primitive spiny lobsters use magnetic fields to navigate. It sounds like that can detect very subtle variations in the strength of the Earth's magnetic field, as a boy scout with a compass would be unable to what the lobsters do.

The Earth's magnetic field is known to be unstable, and has flipped many times. Somehow the lobsters have adapted.

Homing pigeons and turtles are also thought to use magnetic fields, but they are also much more advanced creatures.

Andy writes:

I read Roger's NY Times article about lobsters. It perpetuates the 50-year-old myth that magnetism explains migration. No experiments have demonstrated such causation, nor is there any plausible magnetic detectors in the creatures for it. People believe in magnetic migration simply because they believe in materialism, and can't think of another cause.

The NY Times article caters to this belief, like a horoscope column. A UNC grad student first showed that lobsters taken 10 miles from their home in a container will always walk in the direction of their home. Well, that remarkable phenomenon is true for many species. But then the student pretended to prove that magnetism was the cause by experimenting with a couple of field patterns. Takes a lot more than that to earn a respectable PhD, and prove causation. But don't expect NY Times readers to demand to see the actual data.

The scientist says he could get the lobster to go anywhere by producing an appropriate magnetic field. Isn't that convincing? How do you think the lobsters navigate?

Is this one of Andy's action-at-a-distance theories? In other news, scientists claim to have measured the speed of gravity propagation, and it is near the speed of light, as relativity predicts.

Andy responds:

Roger writes, "The scientist says he could get the lobster to go anywhere by producing an appropriate magnetic field. Isn't that convincing? ...."

No, it's not convincing. The "scientist" (a UNC grad student project) merely said that two different magnetic fields, designed to simulate two different directions from home, resulted in the lobster moving towards the simulated home. It's like saying it rained each time after two Indian rain dances, and therefore the latter caused the former.

To be meaningful, the grad student should test lobster movment under a 100 or so different magnetic fields, and see if there is any correlation. Easy to do, but the real results are not likely to land him in the NY Times.

Roger wrote, "Is this one of your action-at-a-distance theories? In other news, scientists claim to have measured the speed of gravity propagation, and it is near the speed of light, as relativity predicts."

I read two different accounts, and neither was persuasive. The U of MO prof and his colleague claimed to have reworked General Relativity to incorporate a speed of gravity factor. Then, like the dubious eclipse measurements of circa 1919, they claim that minute light deflection measurements prove what they set out to prove. Missing from the discussion are a frank description of the assumptions.

I hope the scientist did the experiment more than twice. He probably did it 200 times.

General relativity implies that gravity propagates in wave form at the speed of light. Apparently gravity could go faster than light under some of the hypothetical quantum gravity theories. I didn't know that. That would be a major (and surprising) result if someone could show that gravity goes faster than light.

Joe writes:

Andy's anti-materialist philosophy is confusing. Does anything have a materialistic explanation? Why believe in any scientific experiment? After all, they all are materialistic. When observing the world, when do we get to the point where materialism starts to fail? At what point does Andy just say "Sorry, we have in this particular case something that is obviously unexplainable by the scientific method, so let's go on to another question, because we have a stone wall here that we can in principle never get through?" Sounds like migration of birds may well be one of these mystery areas.