The baseball player Jose Canseco made a remarkable series of tweets yesterday.
Deja vu, man, deja vu. Any old regulars from the talk.origins usenet group will remember this one: Ted Holden and his endless arguments for Velikovskian catastrophism. Holden also claimed that earth's gravity had to have been much lower for dinosaurs to stand up.
Ted Holden has been repeatedly posting the claim that sauropod dinosaurs were too large to have existed in 1g acceleration. His argument is based on simple square-cube scaling of human weightlifter performance (in particular, the performance of Bill Kazmaier). His conclusion is that nothing larger than an elephant is possible in 1g. His proposed solution is a "reduction in the felt effect of gravity" (by which he seems to mean the effective acceleration), due to a variant of Velikovskian Catastrophism, often called Saturnism. Ted's materials in their current form can be found on his web pages dealing with catastrophism.
For those not familiar with Velikovsky, he was a pseudoscientist whose claim to fame was that he so nimbly straddled two disciplines and befuddled people on either side. He was a classical scholar who used his interpretations of ancient texts to claim there was evidence of astronomical catastrophes in Biblical times (his scholarship there impressed astronomers and left the real classical scholars laughing), while also peddling an astronomical model that had planets whizzing out of their orbits and zooming by Earth in near-collisions that caused the disasters in the Bible and other ancient civilizations (his physics dazzled the classical scholars but had physicists gawping in astonishment at their absurdity).
Holden at least tried to do the math; he just flopped and did it wrong. Canseco hasn't even done that much. Vague and uninformed impressions are not justifications for rejecting science. Here are some quick arguments against this nonsense of dinosaurs living in reduced gravity.
Dinosaurs exhibit the adaptations required for their mass: limbs are thicker in proportion to their length, bones show large muscle insertions, bones are thick and dense, etc. The biology clearly obeys the scaling laws we can see in extant animals.
Holden's mechanism for reducing gravity is ridiculous: he postulates, for instance, that Mars hovered above the Earth and that its gravitational pull countered part of the Earth's pull. It would have to be very close to have that effect, and while it's true that could reduce the 'felt effect of gravity', it would only do so briefly before the two planets collided and destroyed all life, and also, you wouldn't be alive to experience that brief easing of the gravitational load — you'd have been killed in the destructive chaos during the approach, and your body's behavior would probably be dominated atmospheric and geological upheavals anyway.
Canseco's mechanism is pathetic. We already have gravitational variations on the planet, with primary differences between the equator and the poles. These amount to a roughly 0.5% difference in weight — so a 200 pound person weighs 199 pounds at the equator, and 201 pounds at the North Pole. So, most optimistically, if all the gravitational anomalies happened to be piled up on one side of the planet, let's assume that the Mesozoic variation was greater, all the way up to 1% less on the supercontinent. So that 200 ton supersaur Canseco is concerned about would instead weigh…198 tons. Oooh. That's enough to make his objections disappear?
At least Canseco is not as delusional as Holden. But if he starts tweeting about giant teratorns carrying Neandertals on their backs, who then fly to Mars and build giant monuments in Cydonia, get him some help, OK?
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Maybe the dinos were on the 'roids?
I think the funniest thing is that you know Canseco is sitting there trying to figure things out and thinks he's a genius for coming up with all this off the top of his head. Holden and anyone who actually believes this should be ashamed that a steroid addled former ballplayer came up with the same half-assed theories they did. I mean, Canseco's twitter feed is full of insane things he comes up with while "thinking". Nobody wants to end up on that level.
Jose Canseco's best tweet: "I am and will always be just simply a basball player,my tomb stone will just say. Baseball."
also he invented time travel. his twitter feed is a hoot
As I've said before, Canseco was completely right about the steroids and nobody expected that, so, don't just discount him out of hand! ;)
As zomg says: "don't just discount him out of hand"
Dinosaurs and the Expanding Earth
Third Edition 2011 (Hardbook) - ISBN 9780952 26037
In the third tweet he's playing fast and loose with the word, "theory". This kind of thing drives me crazy. It's not a theory, doofus; it's just a conjecture.
So, how does one reduce the "felt" gravity (which is actually the summation of forces).
Well, obviously if there was a change in "felt" gravity, then the forces would have to change. Feel free to chime in if I missed something, but here's a list of forces:
The primary components in our weight on Earth today is our acceleration towards the Earth from Gravity, counteracted by the outward force from the spin of the Earth (Centrifugal force).
The Normal force is the force exerted on us from pressing against the ground and is what prevents us from falling through to the center of the Earth. This force is always the exact force required to cause the sum of all forces to be 0. It increases as Earth gravity increases and decreases as the centrifugal force increases.
Other Gravity would be from celestial bodies like the Moon, planets and stars. This is not considered significant today. Assuming no major changes in celestial bodies, we will ignore this for now.
The formula for gravitational force is a=GM/r^2.
a is the acceleration of a body towards the earth from earth gravity.
G is the universal gravitational constant
M is the Mass of the Earth
r is the radius from Earth center to sea level.
In order to change "a":
-You can change any of the other variables. G for instants is reported as a constant, but as we all know, it's really only more of a suggestion... ;) Seriously though, it is possible that some constants do change over a long enough time span, but it likely didn't change by much over a few million years.
-M is a plausible variable to change. Assuming the radius of the Earth doesn't change, if the mass of the Earth was 1/2 of it's current, then "felt" gravity would be 1/2. However, since the mass doubled, but the radius didn't that means the Earth would be 2x as dense today. The Earth is already made of Iron which is some of the most dense stuff in this solar system (in large quantity). Mass is not likely the only thing that changed in order to cause this "felt" gravitational force.
-r could have changed over millions of years, but assuming that the mass of the Earth hasn't changed dramatically, Hurrell's supposition that the Earth was smaller doesn't make sense. The smaller the "r" with a constant mass, the more dense the matter and the higher the "felt" gravity. Canseco, on the other hand, suggested that the Earth was bigger. If the Earth was 41% bigger millions of years ago, then the felt gravitational force would be 1/2. I can't argue that the Earth hasn't shrank and become more dense over millions of years, but I think a 40% drop in size would probably leave some very obvious marks.
That leaves centrifugal force. If the Earth were revolving much faster, it could effectively reduce the felt gravitational forces. The idea of the Earth's revolution slowing down is definitely plausible. If we suddenly acquired the moon around the time in question, or there was some other celestial event (like a planet, comet, etc.) that stole some of our spin, we could have suddenly felt heavier.
As for if the dinosaurs were structurally built capable of living in our current force vectors, I'm not a mechanical engineer. But I would be curious to have someone explain why all the animals did suddenly (geologically speaking) get smaller.
Actually, I would like to add, as an after thought, that most of the asteroids and such are fairly dense iron rocks. Just for argument that the average asteroid/meteor that fell to Earth had the same density as the Earth, then the Mass of the Earth simplifies to a function of the radius of the Earth and then the Force of "felt" gravity also becomes proportional to the Earth's radius:
a = GM/r^2
M = Volume * Density
Volume = pi*r^3*4/3
=> M = Density * pi * r^3 4/3
=> a = (G * Density * pi * 4 * r^3) / (3 r^2)
=> a = G * Density * (4/3) * pi * r
So, between the time that the dinosaurs were large and the time when everything shrank, the Earth's radius would have to increase a little less than 2x when you consider the loss of centrifugal force as the Earth's revolution slows.
I don't know. It seems unlikely, but then again, there is evidence to support an E.L.E. around that time. It's not like all of that mass would have to come from a single object. The mass could have come from impacts over 1000 or even 10,000 years.
Can we simplify the discussion to - these people are idiots.
So obvious, in fact, that the Earth clearly hasn't shrunk in a long time.
But we didn't. It formed in a collision of a Mars-sized planet with the proto-Earth 4.51 billion years ago; there's no other way to explain its existence, its size, and its composition all at once.
You mean a collision large enough to sterilize the planet several times over? Well, that obviously hasn't happened in the last 3.9 billion years at the very least. :-)
Biomechanics is a science nowadays. There is absolutely no problem with the existence of any known dinosaur in modern gravity; even the largest pterosaurs would have no problem flying – and even taking off from the ground – in today's gravity and atmosphere.
Didn't happen. Instead, the big ones died out along with lots of the small ones, and then the surviving small ones diversified again, reaching the size range they could within about 30 million years.
There are reasons why terrestrial placental mammals can't grow to the size of most sauropods. But that's because they 1) have very, very slow reproduction, so anything that kills the adults wipes the entire population out; 2) chew their food, so they need a huge, heavy head; 3) lack an air-sac system, so can't grow a neck much longer than a giraffe's and still breathe.
It's painfully obvious that that didn't happen.
That would be a bombardment dense enough to sterilize the planet hundreds of times over. Forget about it.
Look, the guy is not a scientist. He is a regular guy. And he is thinking, trying to get answers to some tough questions. He is not saying he is right, he is posing hypotheses.
And you guys ridicule someone who is trying to think things through.
Great Scientists you are
Ridiculing? I see several very serious attempts to show where his hypothesis is clearly wrong.
David, seriously? Smoke some pot or something man - get laid, whatever.
...love your Museum by the way...
Another shining example of "I'm a celebrity, so my thoughts and comments are worth considering, no matter how boneheaded they are".
As to the "he's stating hypotheses" notion, "Ancient gravity was much weaker" is a declarative statement, not a hypothesis.
Also, it's actually an interesting question when an animal is too heavy to fly and when it's too heavy to stand. Actual, interesting science has been done on these questions. :-) And of course, half a century ago, many scientists believed that the biggest dinosaurs couldn't have spent much time on land because they were too heavy, and just a few years ago there were people who thought the biggest pterosaurs were too heavy to fly (though what's actually wrong here, most likely, was their mass estimate).