toldailytopic: How old is the earth?

[The Barbarian]

Barbarian. You have admitted that the earths pull on the tidal bulge of the moon slowed down its rotation.

Couldn't be. The Earth can't pull on itself. Remember the sailboat thing. You're bolting a fan on the deck, and hoping it will make the boat move. Can't do it.

There is no friction there.

Notice all those articles by physicists and astronomers who point out that tidal friction is what slows the Earth's rotation. Would you like to see them again?

If the moon can slow down without friction so can the earth.

But as you learned, tidal friction was the cause of the moon slowing down. It's just that the tidal forces on the sea are much greater than the relatively tiny bulge in the rocks of the Earth.

All it takes is the pull and resistance to slow it down. You insist that ocean friction against against tidal bulges is THE reason for the slowdown.

No. You still don't get it. Why not go to one of those astronomy sites and learn from them?

What evidence do you have that the energy lost due to friction is greater than the pull of the moon on the bulge and the resistance and the energy converted to loss of angular momentum?

The friction is the reason we have the added pull on the moon. Rotation of the Earth causes the bulge to move slightly ahead of the moon (friction does this). The bulge then slightly pulls the moon forward, accelerating it. The frictional losses reduce the kinetic energy of the Earth, and transfer it to the Moon.

Take some time to read up on it.

 

[voltaire]

i said that you admitted that the earths pull on the moons tidial bulge slowed down the rotation OF THE MOON! you misread what i posted.

 

[The Barbarian]

Ah, I see. But it works the same way on the Moon, except, of course, the effect is much smaller, relative to the size of the Earth, because the tidal bulge of rock is so small, relative to that of the oceans.

Barbarian. Would you agree with the following equation for lunar rate of recession? dr/dt = k/R^6 where R is the semi major lunar axis of its orbit around the earth and t is time and K is a proportionality constant?

I'm afraid you're going to have to derive that one for me. I don't see how that can work. Tell me how you got there.

Actually, maybe I do see what you are trying to do, but do explain, so we can see for ourselves.

 

[voltaire]

All that equation is saying is that the recession rate of the moon at any one radius of its orbit is inversely proportional to the 6th power of that radius. It is derived from newtons law of gravity between 2 masses and the equation for angular momentum.

 

[voltaire]

George darwin is the first to formulate that differential equation. He was the son of charles darwin.

 

[The Barbarian]

All that equation is saying is that the recession rate of the moon at any one radius of its orbit is inversely proportional to the 6th power of that radius. It is derived from newtons law of gravity between 2 masses and the equation for angular momentum.

I got that. But it's not obvious why you think so. Do me the favor of showing me how you got that one. It's not, as you probably guessed by now, the one used by physicists and astronomers.

Tell me how you got that formula.

George darwin is the first to formulate that differential equation.

I don't think so. His estimate was 56 million years, which that equation won't give you.

Apparently, it was first used by Don DeYoung, a YE creationist. But other than the fact that it gives him the answer he wants, I don't see any reasoning behind it.

I'd be open to hear about it, if you know.

 

[voltaire]

You acknowledge the earths pull on the solid bulge of the moon but say that the solid bulge on the earth is small. it is one meter. But thats still a lot of mass. My point is that there is a lot of resistance to the moons pull on the total bulge than just the amount encountered when the ocean bulge contacts earths beaches.

 

[voltaire]

I can find the website that shows darwin agreed with that equation. I will have to dig for it. I saw the derivation too but will have to dig for that too.

 

[Stripe]

Barbie keeps wanting to talk about friction slowing the earth, but ignores the fact that the earth's rotation transfers kinetic energy to the water. You can't have it both ways, Barbie. If the earth is imparting kinetic energy to the water then that energy remains part of the force rotating the earth. What you need to slow the earth's rotation is an outside influence. That outside influence is gravity from the moon. It is gravity that slows the rotation of the earth. Friction need not apply.

 

[The Barbarian]

You acknowledge the earths pull on the solid bulge of the moon but say that the solid bulge on the earth is small. it is one meter. But thats still a lot of mass.

There's way to check that. What is the maximum displacement of water in the tides? If you check, you'll find the tidal friction due to water is much greater than the tidal friction due to rock.

My point is that there is a lot of resistance to the moons pull on the total bulge than just the amount encountered when the ocean bulge contacts earths beaches.

It counts on the sea bottom, too. Physicists and astronomers have shown that the great majority of it is from the ocean tides.

I can find the website that shows darwin agreed with that equation. I will have to dig for it. I saw the derivation too but will have to dig for that too.

Good. I'd like to see it. I suspect someone thought that the sixth power was appropriate because the tidal amplitude of the Moon is proportional to the inverse cube of the distance from the Earth, and the tidal acceleration is proportional to the square of the amplitude of the tide, although it would be pretty foolish to do so.

Given the geological evidence of tides, it appears that De Young's equation has established a lower limit of about 1.2 billion years for the age of the moon. It seems Walt Brown was the first to turn this upside down, and in spite of the evidence, argue that the recession was actually greater even though tidal frequency would have been less not greater when the Moon was closer to the Earth.

 

[The Barbarian]

Barbie keeps wanting to talk about friction slowing the earth, but ignores the fact that the earth's rotation transfers kinetic energy to the water.

By friction. That's why physicists call it "tidal friction."

You can't have it both ways, Barbie. If the earth is imparting kinetic energy to the water then that energy remains part of the force rotating the earth.

You're still thinking like that guy who wants to make his boat go by mounting a fan on his sailboat. It won't work that way. The kinetic energy of the Earth is lost by friction, which moves the tidal bulge ahead of the Moon, which then pulls on the moon, accelerating it, and making it recede from the Earth.

In this way, energy is transferred from the Earth to the Moon.

 

[Stripe]

There's way to check that. What is the maximum displacement of water in the tides? If you check, you'll find the tidal friction due to water is much greater than the tidal friction due to rock.

No, it's exactly the same. An equal mass of rock and and equal mass of water sitting at the same elevation on earth* will produce exactly the same amount of friction as each is drawn, by gravity, toward the moon against the rotation of the earth.

The rock is affected only a little because of the strength of the bond between its molecules and the earth's. The water is affected a lot because its chemical bond to the earth is weak. The weaker bond allows the water to move, but the same amount of energy is expended to stop the motion of the water as is expended to stop the motion of the rock.

The only difference between water and rock is the amount of mass that is displaced. The amount of mass displaced allows gravity to have more effect on one than the other.

*surface area of contact might provide a difference.

You need to acknowledge this point, Barbarian, or show how it is wrong.

It seems Walt Brown was the first to turn this upside down, and in spite of the evidence, argue that the recession was actually greater even though tidal frequency would have been less not greater when the Moon was closer to the Earth.

It is completely counter-intuitive to suggest the moon's recession rate has been increasing. What force is going to increase the rate the moon recedes as it continues to get farther from the earth?

Magic? :idunno:

By friction. That's why physicists call it "tidal friction."

Yes, by friction. That water is now in motion and the same stuff, friction, will give that energy right back to the earth system it is part of.

A given mass with the energy to rotate does not slow down because some parts of that mass are not rotating in the same way as other parts. It slows down because of an outside influence. The only outside influence significantly affecting the earth (unless you think the oceans are not part of the earth lain is the moon. And it is certainly not friction from the moon that is causing the earth's rotation to slow. It is gravity. Friction need not apply.

You're still thinking like that guy who wants to make his boat go by mounting a fan on his sailboat. It won't work that way. The kinetic energy of the Earth is lost by friction, which moves the tidal bulge ahead of the Moon, which then pulls on the moon, accelerating it, and making it recede from the Earth.

You're trying to argue friction into the equation at every point when it is completely unnecessary. The moon will recede from the earth because it responds to the gravitational environment created by the relationship between the two bodies. Yes, friction can be used to measure how quickly that recession might proceed, but friction does not cause the earth's rotation to slow. The earth's rotation slows because of gravity.

Unless you think the earth is scraping against the moon. lain:

In this way, energy is transferred from the Earth to the Moon.

Friction transfers energy from the earth to the water on the earth. How does it get from the earth to the moon?

 

[The Barbarian]

No, it's exactly the same. An equal mass of rock and and equal mass of water sitting at the same elevation on earth* will produce exactly the same amount of friction as each is drawn, by gravity, toward the moon against the rotation of the earth.

The point, Stipe, is that it's not equal.

All astronomers should understand tides because they cause tidal friction and that's what causes the Moon to face us. The ocean tides are an obvious effect of the Moon's gravity but the Moon causes "land tides" to occur too. As the Moon passes overhead the Earth rises towards it by several centimeters and then drops down again as the Moon moves on. (Actually, as the Earth rotates.) Don't confuse this with the tug of the Moon that causes the Earth to move towards it, producing the lower high tide opposite the Moon. What I am talking about here is the actual distortion of the Earth's solid "rock" due to the Moon's gravity! These land tides are not noticeable because the shifting they cause is very slight, very slow, and the rock returns to the same position as the Earth rotates. It has no overall effect on the Earth's position or shape.

http://www.synapses.co.uk/astro/moon1.html

The only difference between water and rock is the amount of mass that is displaced. The amount of mass displaced allows gravity to have more effect on one than the other.

No. It's the size of the bulge, and the mass that matters.

You need to acknowledge this point, Barbarian, or show how it is wrong.

You've already seen this, Stipe.

Barbarian chuckles:
It seems Walt Brown was the first to turn this upside down, and in spite of the evidence, argue that the recession was actually greater even though tidal frequency would have been less not greater when the Moon was closer to the Earth.

It is completely counter-intuitive to suggest the moon's recession rate has been increasing.

Nevertheless, the arhythmite evidence shows it is. And the physicists can easily show that the fewer tides, the less force.

Magic isn't the answer, Stipe.

Barbarian observes:
By friction. That's why physicists call it "tidal friction."

Yes, by friction.

That took a long time for you to get.

That water is now in motion and the same stuff, friction, will give that energy right back to the earth system it is part of.

No. Tidal friction shifts the bulge ahead of the moon, and that potential gravitational energy (caused by the friction pulling the bulge forward) is then transferred to the moon by gravity.

A given mass with the energy to rotate does not slow down because some parts of that mass are not rotating in the same way as other parts.

It slows down because of an outside influence. The only outside influence significantly affecting the earth (unless you think the oceans are not part of the earth ) is the moon.

You have that. You were just convinced tidal friction has nothing to do with it. Apparently, you've come to realize that much, now. What you're missing is how the energy is transferred from the Earth to the Moon.

Barbarian chuckles:
You're still thinking like that guy who wants to make his boat go by mounting a fan on his sailboat. It won't work that way. The kinetic energy of the Earth is lost by friction, which moves the tidal bulge ahead of the Moon, which then pulls on the moon, accelerating it, and making it recede from the Earth.

You're trying to argue friction into the equation at every point when it is completely unnecessary.

As you learned, physcists and astromers know better. Remember all the articles I cited by physicists and astronomers, who attributed the effect to tidal friction? Would you like to see them again?

Barbarian observes:
In this way, energy is transferred from the Earth to the Moon.
Friction transfers energy from the earth to the water on the earth.

How does it get from the earth to the moon?

Friction moves the tidal bulge ahead of the Moon. The bulge then exerts a gravitational force on the moon because it's not directly under the Moon. The energy required to do this is taken from the kinetic energy of the Earth's rotation, and is then transferred to the Moon.

 

[Stripe]

The point, Stipe, is that it's not equal.

It is equal. If the same amount of kinetic energy is imparted to two substances of equal mass then the same amount of friction will be recorded in bringing the two masses to a halt.

It's called conservation of energy, Barbie. You might want to read up on it. :up:

No. It's the size of the bulge, and the mass that matters.

Yes, because that is what gravity can act upon.

You've already seen this, Stipe.

Then you won't mind pointing it out again. :up:

Magic isn't the answer, Stipe.

What is the answer? If the moon is receding at a known rate today (3.8cm/century), what is going to cause it to recede at a faster rate when it is further away?

By friction. That's why physicists call it "tidal friction."

How is tidal friction going to increase the recession of the moon when the tides will become smaller and the attraction between the tidal bulge and the moon will decrease?

Here's the answer. It won't. Gravity is the only factor in the earth-moon system that controls the two bodies. Friction on one is friction on one. That energy remains on its own body. Friction on the moon is friction on the moon. It does not affect the earth. Friction on the earth is friction on the earth. It does not affect the moon.

That took a long time for you to get.

No it didn't. You're lying again. I have always been perfectly comfortable with the fact that there is friction on the moon and on earth between rock & water, water & water and rock & rock. I've never said anything that might suggest I did not understand that.

What I am denying the possibility of is that friction has any part to play in the relationship between the earth and the moon. The only way significant energy can be transferred from the earth to the moon is via gravity. Unless you think the moon is scraping along the earth. lain:

No. Tidal friction shifts the bulge ahead of the moon, and that potential gravitational energy (caused by the friction pulling the bulge forward) is then transferred to the moon by gravity.

Wow. So what part does friction play in this whole thing? Gravity pulls water toward the moon. The earth's rotation shifts that tidal bulge away from the direct line. Then gravity acts on the bulge.

And you're going to call friction the causative factor for the moon's recession rate?

Wow. lain:

Atheists will create anything to protect their paradigms.

You have that. You were just convinced tidal friction has nothing to do with it. Apparently, you've come to realize that much, now. What you're missing is how the energy is transferred from the Earth to the Moon.

Tidal friction has nothing to do with transferring energy from the earth to the moon. That would be gravity. Unless you think the earth is scraping against the moon. lain:

You're still thinking like that guy who wants to make his boat go by mounting a fan on his sailboat. It won't work that way. The kinetic energy of the Earth is lost by friction, which moves the tidal bulge ahead of the Moon, which then pulls on the moon, accelerating it, and making it recede from the Earth.

The kinetic energy of the earth is not lost. It is transferred to the water. The water is part of the earth system. The entire earth system is affected by gravity from the moon.

It is gravity and gravity alone that decides the relationship between the earth and the moon.

But, y'know what? You could probably write gravity in terms of friction and develop a model to describe the earth-moon relationship. It would most certainly be a large and unwieldy thing.

Do you have it? Because I have a model that describes what I'm talking about.

As you learned, physcists and astromers know better. Remember all the articles I cited by physicists and astronomers, who attributed the effect to tidal friction? Would you like to see them again?

Sure. Post away. :idunno:

Friction moves the tidal bulge ahead of the Moon. The bulge then exerts a gravitational force on the moon because it's not directly under the Moon. The energy required to do this is taken from the kinetic energy of the Earth's rotation, and is then transferred to the Moon.

Like I say, it's all gravity. Friction need not apply.

 

[The Barbarian]

Barbarian observes:
The point, Stipe, is that it's not equal.

It is equal.

Can't be. You cannot change velocity without an unbalanced force.

If the same amount of kinetic energy is imparted to two substances of equal mass then the same amount of friction will be recorded in bringing the two masses to a halt.

No. Ke = ½ mv2

It's called conservation of energy, Barbie.

Which is why the frictional force that moves the tidal bulge is transferred to the moon.

You might want to read up on it.

I've cited numerous places where you can learn how it works.

Barbarian chuckles:
By friction. That's why physicists call it "tidal friction."

How is tidal friction going to increase the recession of the moon when the tides will become smaller and the attraction between the tidal bulge and the moon will decrease?

They become more frequent. And as you learned, the distribution of the continents affects the force.

Gravity is the only factor in the earth-moon system that controls the two bodies.

The laws of physics say you're wrong. Sorry.

Friction on one is friction on one. That energy remains on its own body.

Wrong. The frictional force that keeps the bulge ahead of the moon is largely transferred to the moon.

Barbarian chuckles:
That took a long time for you to get.

No it didn't. You're lying again.

C'mon Stipe. You wiggled every which way trying to get around that.

Barbarian observes:
No. Tidal friction shifts the bulge ahead of the moon, and that potential gravitational energy (caused by the friction pulling the bulge forward) is then transferred to the moon by gravity.

Wow.

Yep.

Stipe makes one last attempt to save his paradigm:

So what part does friction play in this whole thing? Gravity pulls water toward the moon. The earth's rotation shifts that tidal bulge away from the direct line. Then gravity acts on the bulge.

And you're going to call friction the causative factor for the moon's recession rate?

Astronomers do, because it wouldn't happen without tidal friction.

Wow.

Yep.

Atheists will create anything to protect their paradigms.

You sure do, Stipe.

Barbarian chuckles:
You have that. You were just convinced tidal friction has nothing to do with it. Apparently, you've come to realize that much, now. What you're missing is how the energy is transferred from the Earth to the Moon.

Tidal friction has nothing to do with transferring energy from the earth to the moon.

Physicists and astronomers don't agree with you.

Barbarian observes:
You're still thinking like that guy who wants to make his boat go by mounting a fan on his sailboat. It won't work that way. The kinetic energy of the Earth is lost by friction, which moves the tidal bulge ahead of the Moon, which then pulls on the moon, accelerating it, and making it recede from the Earth.

The kinetic energy of the earth is not lost. It is transferred to the water.

And then to the moon. That's how it works.

Do you have it? Because I have a model that describes what I'm talking about.

So did the guys who wanted to prove the Earth is flat. They had the same problem you've got with your "model."

Barbarian observes:
As you learned, physicists and astronomers know better. Remember all the articles I cited by physicists and astronomers, who attributed the effect to tidal friction? Would you like to see them again?

 

[Stripe]

And then to the moon. That's how it works.

Wrong. When kinetic energy is added to the oceans of the earth that energy is returned to the earth by friction.

You're creating an unnecessary divide. The water is on the earth. The earth is rightly considered as a whole (all mass, rock and water) in calculations of orbital parameters.

 

[The Barbarian]

I know you want us to believe it, Stipe. But we can believe you, or all those astronomers and physicists. Your field of expertise is what...?

 

[Stripe]

I know you want us to believe it, Stipe. But we can believe you, or all those astronomers and physicists. Your field of expertise is what...?

I prefer people with the capacity to think through an issue for themselves and people who are able to explain what is wrong with what I say. :thumb:

 

[The Barbarian]

I prefer people with the capacity to think through an issue for themselves and people who are able to explain what is wrong with what I say.

Speaking of which, you never did explain where the numbers for that "model" come from. Why a sixth power?

That was pretty funny from the cut-and-paste king. What's wrong with what you say is, that it ignores tidal friction, without which the off-center tidal bulge would not exist. And without that, there would be no recession of the moon.

And you haven't yet told us your particular field of expertise. What did you say it was?

 

[Stripe]

Speaking of which, you never did explain where the numbers for that "model" come from. Why a sixth power?

I think you need to practice remembering who it is you talk to. If you have problems with the numbers from my link then tell us why. But I think this is the first time you've even mentioned it.

That was pretty funny from the cut-and-paste king.

:squint:

What have I cut and pasted?

Are you on drugs?

What's wrong with what you say is, that it ignores tidal friction, without which the off-center tidal bulge would not exist. And without that, there would be no recession of the moon.

Except I have never ignored friction. You need to understand what you're arguing with before you ridicule it. :thumb:

And you haven't yet told us your particular field of expertise. What did you say it was?

Calling atheists on their bluffs. :up: