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Astrology Science / Gravity Question

SkepticalScience

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S
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Jul 2, 2003
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I heard something yesterday that I couldn’t think of a counter argument for.

This guy claimed that the underpinning of astrology is rooted in gravitational theory. Every object in the universe exerts gravitational pull on every other object in the universe – if ever so slightly. So, our sun for instance, exerts SOME gravitational pull on say. . . . a rock on a moon in some planet in the crab nebula. It might be ever so slight, but if we had a machine sensitive enough to detect it, it would register the effect of gravity.

If you buy that assumption (which I am not sure I do), then if say Venus was a 100 meters closer to the earth, it could effect a brain neuron that could make you happier that day or something. The point being, that the motion of the objects in the universe DO effect our brain in some way, which might manifest itself in behavior changes.

Of course I think this whole theory is bunk. But I didn’t have a clear counter argument. Any ideas??

And what about that assumption that every object in the universe exerts gravity on every other object in the universe? Why doesn't gravity run out after a billion light years or something?

SS
 
The person who pulled you out of the womb and spanked you generates a bigger gravitational force on you.
 
Right, well, I understand that the EFFECT of the gravity is weak – but that doesn’t mean that in principle that slight bit of force acting on a neuron in your head, could potentially change your behavior.

Right??
 
First, have them show some evidence it works. Then we can talk about mechanism.

--Terry.
 
Well, yeah, it could hypothetically influence the neurons moving around by a very small degree, but passing insects would overshadow any influence from the planets or stars. It'd be like calculating how the tiniest and most distant butterflies affect the weather while ignoring local sources of change.
 
In principle, that may be correct. You'd first have to assume that gravity has an effect on your brain at all, and then assume that the effect might manfest itself as a change of mood... that's an easy experiment which we've all already done - do you feel happier when you lie on your back? Do you feel sad when you lie on your side? You can probably be fairly confident, from your everyday experiences, that any gravitational affect on your brain will not affect your mood.

But, further to that, my initial 'in principle' is very important. In practice, as BronzeDog suggested, the gravitational force from Venus is almost certainly *not* detectable, as it will be completely swamped by the noise of closer, if less massive objects. I haven't tried to do the maths, but I would guess that the extra mass of air in a high-pressure weather system ten miles away would have a bigger gravitational effect on you than Venus moving a million miles closer.

Hmm... I might just do that maths for fun anyway... :)
 
Ahhh.

Those responses make a lot of sense. Those are exactly the counter arguments I wish I had thought of.

Me to gravity guy: "So are you saying, that we should have a whole field devoted to measuring the gravitational impact of insects on our moods? The insects gravity would be more pronounced than that of venus. Also, why don't my moods change when I lie on my back? Or on my side?"

BRILLIANT!

Thanks guys!
 
I would have held out a small object and said

"The gravitational attraction of this object to you is greater than that of any of the planets right now. So you're telling me you believe this grapefruit controls your destiny?"
 
You know this brings up one big problem with a lot of supernatural claims: Just because something has an effect on something else doesn't mean it has a meaningful effect.
So that increadibly slight change in gravitational pull is going to somehow affect everyone born on earth that day in the same way, huh? And they're all going to develop similar personality traits?
Being outgoing is something that's triggered by a completely random tiny force?

My point being, even if it the gravitational pull of the planets were somehow significant, how exactly would it cause a person's personality to develop in a certain way?
Imagine you were trying to make a machine that changed people's personalities by altering the gravitational effects of nearby stellar objects. Even if you had a perfect understanding of the brain, even if it were possible, this would be a very intricate machine indeed. Yet somehow the planets just manage to do it at random?

To me it seems about as likely as someone giving birth to a mutant with fully developed gills, webbed hands and feet, and a digestive system designed to deal with eating fish.
 
This also seems like "post-hoc" rationalizations...I mean (and I am, as always, prepared to be wrong) was not most astrology, methodology and "science" developed prior to modern gravitational theory? I mean, the ancients didn't know what planets or stars were, did they? Isn't all this "gravitation" stuff part of a post-hoc explaination that had to be applied post Newton and in light of a braode still developing view of the universe and how it functions?
 
In addition if astrology were somehow gravity-based then the zodiac is irrelevant as it would not matter where the sun was in relation to a set of stars.

The gravitational influence of the Sun and Moon on the Earth is far, far greater than any other object in the solar system and so should completely dominate astrology. Because the position of the Sun and Moon changes quickly relative to the Earth an astrologer would need to know, to the minute, when you were born in order to know where they were at the time.

Using gravity as a mechanism also does not answer the question on why astrology relies on when you were born rather than conceived. What would your birth have to do with it? Gravity works in the womb just fine.
 
headscratcher4 said:
This also seems like "post-hoc" rationalizations...I mean (and I am, as always, prepared to be wrong) was not most astrology, methodology and "science" developed prior to modern gravitational theory? I mean, the ancients didn't know what planets or stars were, did they? Isn't all this "gravitation" stuff part of a post-hoc explaination that had to be applied post Newton and in light of a braode still developing view of the universe and how it functions?
Click to expand...

Yes.

The planets were seen as significant, because even though they were shining dots on the firmament, they moved among the stars. The ancients had no idea that the planets were different types of celestial bodies. All they knew was that the dots moved - they were wanderers, planets.

The gravity explanation came later, and has largely been abandoned today. One exception is the phony "But the moon has the same cycle as women menstruating, so there!" They want it both ways.

Astrology is all about double-thinking.
 
Two very small observations. First, re:gravity. I have sometimes heard students say the gravity effect is tidal. They point to the Bay of Fundy as a demonstration of the power of tides. I then point them to the Great Lakes, which have no appreciable tide at all, then to a local pond which has no detectable tide, then ask them what sort of tidal effects they can expect to see on a body that is A) much much much smaller than the smallest bodies which show tidal effects, and B) mobile, changing its orientation with regard to the heavenly bodies allegedly causing the tidal effects.

Secondly, with regard to these effects having measurable impact on nerve impulses. The answer to that one is easy. :notm Local events on neurons are graded (that is, weak stimuli produce weak reactions), and must reach a particular threshold before they will trigger an "action potential", a nerve signal that will propogate the length of the neuron. Any gravitational effects of that magnitude are well below "noise" levels. We know this because, as someone mentioned above, the heavenly body of the skepchick near you exerts a greater gravitational pull than does the heavenly body of Jupiter, despite their difference in mass. (this works for all instances when a skepchick is close enough to worry about--for greater distances, the inverse-square law can calculate the relative gravitational pulls of, say, Neptune and Renata.) If the gravitational influence of a nearby person is sub-threshold, so is the weaker influence of a planet. What is more, because graded potentials decay, there is no cumulative effect of planetary gravity. So...even talk of a potential, but not meaningful, effect runs counter to the observed evidence.
 
SkepticalScience said:
Right, well, I understand that the EFFECT of the gravity is weak – but that doesn’t mean that in principle that slight bit of force acting on a neuron in your head, could potentially change your behavior.

Right??
Click to expand...
Yes but why would it effect you in the specific way claimed by astrology? Why does Mars exert a force affecting “warlike” characteristics; Why does Venus exert a force affecting “affairs of the heart”, and so on?

It’s all moot though – astrology doesn’t work, so arguing about what force might underpin astrology is like arguing about how a fish rides a bicycle.
 
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RichardR said:
Yes but why would it effect you in the specific way claimed by astrology? Why does Mars exert a force affecting “warlike” characteristics; Why does Venus exert a force affecting “affairs of the heart”, and so on?
Click to expand...

Because of Roman mythology? (I.e. astrology assumes that the planets are the gods they are named after.)


Mosquito - not a mythology nor astrology expert
 
SkepticalScience said:
And what about that assumption that every object in the universe exerts gravity on every other object in the universe? Why doesn't gravity run out after a billion light years or something?

SS
Click to expand...

Are you asking if we 'run out' of gravity, as we would run out of mass eventually? Mass creates it's own gravity, which we are currently having trouble identifying as more than a force.

Or are you asking if a body with a measurable gravitational field (i.e., a star) would have gravitational effects all over the universe simply by existing? The force of gravity decreases as the square of the distance from the object you are - so if you were twice as far from a star, the effect of the star's gravity on you is 1/4, and so on. Usually by the time you get to the next star, the other star won't matter anymore.
 
RichardR said:
They're not though, are they?
Click to expand...

Actually, I don't know enough about either to make that assertment, but Venus is the godess of love and Mars is the god of war and commerce. I have absolutely no idea as to other connections, but I would not be surprised if there are more.

I have this feeling, which may be rather unfounded, that the name given to these heavenly bodies are important to astrologists, i.e. they give the object the properties of the mythological figure they are named after. It makes sense, but may be wrong.


Mosquito - still no expert on astrology nor roman mythology
 
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