The lunar tidal action not only causes lunar recession, it also causes the earth to spin at a slower rate and the moon to spin at a faster rate because as the moon pulls on the tidal bulge against earth's rotation, the moons spin increases while the earths spin decreases.
toldailytopic: How old is the earth?
- Thread starter Nathon Detroit
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When you add all of this up, you realize that the slow down in the earths rotation rate was not linear in the distant past up to the present. It was exponential. This logically means that the lunar recession rate was not the same as todays recession rate and only slightly slower due to continental position. In fact it was exponential faster in the past than it is today.
Read the material from the link. Notice that if the moon is closer, it's period of revolution must be shorter. The square of the orbital period of a planet is directly proportional to the cube of the semi-major axis of its orbit.
And that would lower the tidal frequency, lowering the rate of recession. Notice the evidence of sedimentary rhythmites supports the physics.
So that doesn't give you any help. Do you understand how the energy is transferred?
Since the lunar recession rate was exponentially faster in the past according to distance, an equation has been formulated based on these laws. This equation shows that based on todays rate of 3.82 cm/yr recessional rate and 8.812 milliseconds per year rotational slowing rate for the earth, The moon was in contact with earths surface 1.183 billion years ago.
Not if gravity was working back then. As you learned, the reduced tidal frequency would mean that the recession was less back then. And the evidence in the rocks shows that to be the case.
Barbarian can't even properly assess the criticism of his position. I think your objection to the evidence I provided is circular. I gave a valid and reasonable mathematical model that places a limit on the age of the Earth. You reject that model, but we are required to accept the old age model before doing so.
You cannot assess properly the criticism of your position, how do you hope to understand the evidence you are reading?
No, they don't.
Is this the best you have?
How about you just read it this time? :idunno:
Your math is terrible.
Nothing to refute. Without your working you might as well have just made that number up. :idunno:
(Stipe thinks anyone who doesn't agree with him, can't assess criticism)
Perhaps you don't know what "circular" means. Hint: evidence is not "circular."
Since the evidence shows an old Earth, your "mathematical model" has to conform to the evidence. That's how it works.
Barbarian observes:
I'm just pointing out to you that even honest creationists admit that the evidence indicates an old Earth.
There's no point in denying it, Stipe. I gave you an example. Harold Coffin is a YE creationist, and he admits that without his understanding of the Bible, he'd think the Earth was very old. Or are you going to claim that evidence is "circular", too?
Barbarian observes:
It won't do you much good to deny the evidence. You've seen it; you see that honest creationists admit that it exists. Time to face reality, Stipe.
When even your YE compatriots admit the evidence shows an old Earth, it's time for you to face up to it.
Barbarian suggests:
Sorry. If you think the link is right, present the numbers here for us.
If you don't understand it well enough to present it here, what makes you think it's right?
But today the number can be observed directly, as a result of three-corner mirrors left behind by Apollo astronauts. Lunar laser ranging establishes the current rate of retreat of the moon from Earth at 3.82±0.07 cm/year
Barbarian chuckles:
Let's leave it at 4.0 cm/year, just to give you the benefit of a doubt and to ease calculation. The Roche Limit (distance from the Earth at which the moon would break up from gravitational forces) is about 9,500 km. The moon is presently about 384,000 km away. So, the present rate of recession (which as I said, changes over geologic time) would suggest 9.6 billion years to reach it's present place from the Roche limit. Pick a different distance, and I'll calculate the time for you as well. And then we can see what the tides were at that time.
Not bad for doing it in my head. The actual calculated value is...
9,362,500,000 years.
Barbarian observes:
Yep. The usual. If you ever get up the nerve to support your argument, tell us how far from the Earth you think the moon started, and then we'll check how much time there was, given the rate of recession. Or you could just toss another generic insult and run for cover.
Barbarian chuckles:
Yeah, like that. Like everyone else here, I figure if you had something that refuted the numbers I gave, you'd lay it out for us.
Well, you could do the math yourself. But if you don't know how, I'll do it for you:
384,000 km - 9,500km = 374,500 km.
Or about 37,450,000,000 cm.
Divide by 4 cm/year, you get 9,362,500,000 years since the moon would have been at the Roche limit.
Uh, yeah dude .. you didn't provide any evidence. :nono:
The evidence shows a young earth. :idunno:
The evidence is in the mathematical earth-moon model I provided.
Great. I know an atheist who believes life was started by space aliens.
Your math is still terrible.
lain::rotfl:
Oh, Barbie. You're priceless! :darwinsm:
Barbarian suggests:
Perhaps you don't know what "circular" means. Hint: evidence is not "circular."
Yep. Doesn't know what it means. "Circular" seems to be your mantra against evidence.
Barbarian observes:
Since the evidence shows an old Earth, your "mathematical model" has to conform to the evidence. That's how it works.
As you learned, even honest creationists say that the evidence is for an old Earth.
Models are not evidence. And when we do the math, we get billions of years.
Barbarian chuckles:
There's no point in denying it, Stipe. I gave you an example. Harold Coffin is a YE creationist, and he admits that without his understanding of the Bible, he'd think the Earth was very old. Or are you going to claim that evidence is "circular", too?
Atheists and creationists have odd ideas sometimes.
Barbarian chuckles:
Let's leave it at 4.0 cm/year, just to give you the benefit of a doubt and to ease calculation. The Roche Limit (distance from the Earth at which the moon would break up from gravitational forces) is about 9,500 km. The moon is presently about 384,000 km away. So, the present rate of recession (which as I said, changes over geologic time) would suggest 9.6 billion years to reach it's present place from the Roche limit. Pick a different distance, and I'll calculate the time for you as well. And then we can see what the tides were at that time. Not bad for doing it in my head. The actual calculated value is...
9,362,500,000 years.
"Terrible" meaning "it gives a result that scares Stipe."
Barbarian observes:
Well, you could do the math yourself. But if you don't know how, I'll do it for you: 384,000 km - 9,500km = 374,500 km. Or about 37,450,000,000 cm. Divide by 4 cm/year, you get 9,362,500,000 years since the moon would have been at the Roche limit.[/QUOTE]
Well, at least you aren't calling me an atheist this time. I gather, since you've declined to name a distance for the "original moon position", that you've realized your "model" is junk. Next time, think.
Perhaps you don't know what "circular" means. Hint: evidence is not "circular."
Yep. Doesn't know what it means. "Circular" seems to be your mantra against evidence.
Barbarian observes:
Since the evidence shows an old Earth, your "mathematical model" has to conform to the evidence. That's how it works.
As you learned, even honest creationists say that the evidence is for an old Earth.
Models are not evidence. And when we do the math, we get billions of years.
Barbarian chuckles:
There's no point in denying it, Stipe. I gave you an example. Harold Coffin is a YE creationist, and he admits that without his understanding of the Bible, he'd think the Earth was very old. Or are you going to claim that evidence is "circular", too?
Atheists and creationists have odd ideas sometimes.
Barbarian chuckles:
Let's leave it at 4.0 cm/year, just to give you the benefit of a doubt and to ease calculation. The Roche Limit (distance from the Earth at which the moon would break up from gravitational forces) is about 9,500 km. The moon is presently about 384,000 km away. So, the present rate of recession (which as I said, changes over geologic time) would suggest 9.6 billion years to reach it's present place from the Roche limit. Pick a different distance, and I'll calculate the time for you as well. And then we can see what the tides were at that time. Not bad for doing it in my head. The actual calculated value is...
9,362,500,000 years.
"Terrible" meaning "it gives a result that scares Stipe."
Barbarian observes:
Well, you could do the math yourself. But if you don't know how, I'll do it for you: 384,000 km - 9,500km = 374,500 km. Or about 37,450,000,000 cm. Divide by 4 cm/year, you get 9,362,500,000 years since the moon would have been at the Roche limit.[/QUOTE]
Well, at least you aren't calling me an atheist this time. I gather, since you've declined to name a distance for the "original moon position", that you've realized your "model" is junk. Next time, think.
Barbarian. Gravity was indeed working back then and the effect was opposite of what you say i learned. You did not understand what i wrote. Gravity was 4 times greater when the moon was half the distance from the earth as it is today. This greatly slowed down the rotation rate of the earth and hence the recession speed. Here is where you are confused. You think that means it was greatly reduced from todays rate of recession.
The greater gravity at half the distance and thus slower rotational rate greatly reduced the recession rate AT THAT TIME. In order for that rate to be lower than todays rate, the rate would have to have been sped up. A slower earth rotation rate will not speed up the recession rate. It will slow it down.
Since you cant speed up the recession rate as gravity becomes less as distance grows greater and the fact that the gravity was 4 times as great at half the distance, and therefore the recession rate was at least 4 times greater at that point, The recession rate had to be greater the closer the moon was to the earth. Its impossible for the recession rate to have been less than todays at any point in the past.
I understand what you wrote. I'm just pointing out that it's hooey.
Gravity is exactly now what it was then. You mean that the Earth exerted four times the force on the Moon. But that's not what slows the Earth down and causes the Moon to move outward. It's the tides. As you learned, Kepler's Laws show that the period of revolution of the moon at that distance would be shorter (about 0.63 the present period) That means the frequency of tides would be reduced, and the recession would thereby be less, assuming the existing coastlines were roughly the same as now.
No.
http://www.talkorigins.org/faqs/moonrec/tide-friction.jpg
The ocean bulge is pulled in front of the moon by Earth's spin; since the ocean is gravitationally stuck to the Earth, it has to go where the Earth goes. But it can't go too far, because it is pulled back by the moon. The result, illustrated in figure 3, is that the ocean bulge is in equilibrium, remaining essentially fixed with respect to the Earth and moon, while the solid Earth spins under the ocean. The ocean is gravitationally bound to the Earth, but it is still fluid, and not stuck to the Earth the way a rock or a mountain is. There is an interface, namely the ocean bottom, where the water and the Earth are free to move with respect to each other. That interface, like any other real physical interface, is not totally frictionless, and that too is illustrated in figure 3 by the small caption that reads "Friction force". But in this case, "friction" includes all of the ways that the ocean and the Earth impede each other. The ocean runs into the continents and has to wash around them (so how they are distributed around the Earth makes a difference).
Since the Earth is trying to spin forward, but the ocean is held back by the moon, the Earth winds up trying to move through the oceans. Just as you can feel the resistance if you try to walk through water, so the Earth feels the resistance trying to move through the water of the oceans, and that resistance transfers energy from the Earth (causing its spin rate to slow), and to the oceans (sloshing them around and heating them up). But the Earth-ocean system also exerts a torque (a "twisting" force) on the moon, because the line along the arrow labeled "B" in figure 3 is at an angle to the line that connects the center of the Earth to the center of the moon. As a result of that torque, the Earth also transfers energy (causing its spin rate to slow) through the ocean bulge, and gravity, to the moon (causing it to speed forward in its orbit, and therefore move farther away from the Earth)...The years that followed saw the rise of plate tectonics and a major shift in geophysical thinking because of it. The mobility of the drifting continents is a matter of major import, for by this time it was well realized that tidal dissipation in shallow seas dominated the interaction between Earth and the moon. Kurt Lambeck was a major player in the tidal game at that time, authoring several papers. His study of the variable rotation of Earth (Lambeck, 1980) remains the most extensive such study ever done. Lambeck noted that after the struggles of Slichter, Goldreich, and others, the observed and modeled values for tidal dissipation were finally in agreement (Lambeck, 1980, page 286). However, this still left a time scale problem. According to Lambeck, " ... unless the present estimates for the accelerations are vastly in error, only a variable energy sink can solve the time-scale problem and the only energy sink that can vary significantly with time is the ocean." (Lambeck, 1980, page 288). In section 11.4, "Paleorotation and the lunar orbit", Lambeck explicitly points out that paleontological evidence shows a much slower lunar acceleration in the past, and that this is compatible with the models for continental spreading from Pangea (Lambeck, 1980, pages 388-394). It is important to remember that by 1980, Lambeck had pointed out the essential solution to Slichter's dilemma - moving continents have a strong effect on tidal dissipation in shallow seas, which in turn dominate the tidal relationship between Earth and the moon...But what about the past rate of retreat? Paleontological data directly reveals the periodicity of the tides, from which one can derive what the rate of retreat would be to match the frequency. It is also a non-trivial point that it proves the moon was physically there. After all, if your theory implies that the moon was not there at some time in the past, but your observed tidal evidence says that it was there in the past, then it's pretty clear that the theory, and not the observation, needs to be adjusted.
This paleontological evidence comes in the form of tidal rhythmites, also known as tidally laminated sediments. Rhythmites have been subjected to intense scrutiny over the last decade or so, and have returned strong results. Williams (1990) reports that 650 million years ago, the lunar rate of retreat was 1.95±0.29 cm/year, and that over the period from 2.5 billion to 650 million years ago, the mean recession rate was 1.27 cm/year. Williams reanalyzed the same data set later (Williams, 1997), showing a mean recession rate of 2.16 cm/year in the period between now and 650 million years ago. That these kinds of data are reliable is demonstrated by Archer (1996). There is also a very good review of the earlier paleontological evidence by Lambeck (1980, chapter 11, paleorotation)
As you can see, the paleontological evidence indicates that moon today is retreating from Earth anomalously rapidly. This is exactly as expected from the theoretical models that I have already referenced. The combination of consistent results from both theoretical models and paleontological evidence presents a pretty strong picture of the tidal evolution of the Earth-moon system. Bills & Ray (1999) give a good review of the current status of this harmony. Without realizing it, they have also explained well why the creationist arguments are unacceptable.
http://www.talkorigins.org/faqs/moonrec.html
That's what the evidence shows, according to Kepler's Laws, Newton's theory of gravity, and the geological evidence.
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