Decay of earths rotation

Anyone know of a good discussion of the rate of decay of the earth’s angular velocity?



A while back I did some calculations using a viscous damping model. The time constant (based on the known daily loss of angular velocity) resulted in a very short age of the earth; I forget the exact numbers but the surface velocity at the equator exceeded the escape velocity far more recently than would be acceptable to old earthers (<100M years?).



I never could figure out how to model the change in the earth’s eccentricity as a function of velocity, nor did I have any idea how that would affect the time constant (especially at a time prior to the earth forming a single mass). I also didn’t know how to account for changes in angular momentum due to accretion or other mechanisms. And of course, viscous damping may not be the right place to start.



Any thoughts?



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Jesus said to them, "Amen, amen, I say to you, unless you eat the flesh of the Son of Man and drink his blood, you do not have life within you....For my flesh is true food, and my blood is true drink..."
As a result of this, many (of) his disciples returned to their former way of life and no longer accompanied him...
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The rotation of the Earth is no problem for a 4.5 Gyr lifetime.

The Earth's rotation slowing down does not give spuriously high rotation rates in the past. If you get this you are doing the math wrong.

By 'eccentricity' I assume you mean the oblateness of the Earth and are not referencing it's orbit. That isn't easy to calculate because you need an accurate model of the Earth and physical properties of different types of rock etc.

Anyways the Earth's oblateness would change that much so it's not a necessary parameter in a simple model - any effects of this would be a small correction. As would accretion. What accretion are you even referring to?

In fact - how did you end up with problems for the Earth?

Only if you used erroneous numbers could you have got this.

[quote=chilehed]Anyone know of a good discussion of the rate of decay of the earth’s angular velocity?


The slowdown or spindown rate of the earth is due to friction from the tide. The tide is caused by the moon. The moon is moving away from the earth, and at one time the moon could have crashed & bounced off of the earth.

The universe or macro world is not as accurate as the atomic or micro world. Every few years they have to adjust the atomic clocks. Atomic time is fairly consistant, but our solar system is not as consistant. It can fluxuate more than half a second every two or three years.

Hence my question - I rechecked my calculations several times (but we all know that doesn't always help).

[quote]
By 'eccentricity' I assume you mean the oblateness of the Earth and are not referencing it's orbit. That isn't easy to calculate because you need an accurate model of the Earth and physical properties of different types of rock etc.
Anyways the Earth's oblateness would change that much so it's not a necessary parameter in a simple model - any effects of this would be a small correction.QUOTE]

No, it's not easy to calculate, that's what I said, but you seem to be sure of the answer. How is that? And yes, I was referring to the shape of the earth itself, not it's orbit.

The earth's momentum changes as it gains mass from things falling onto it. Nowdays it's not a significant factor most of the time (thank God), but the most widely held opinion is that it was in the past.

Well, as I said, I calculated the time constant of decay from the daily angular velocity loss. I suppose I may have had the wrong rate, but at the time the source seemed reliable. Perhaps I should go back and try again.

The slowdown or spindown rate of the earth is due to friction from the tide. The tide is caused by the moon. The moon is moving away from the earth, and at one time the moon could have crashed & bounced off of the earth.

I imagine that a significant component of it is due to viscous flow in the earth's interior, as well as magnetic field effects.

__________________
The Jews quarreled among themselves, saying, "How can this man give us (his) flesh to eat?"
Jesus said to them, "Amen, amen, I say to you, unless you eat the flesh of the Son of Man and drink his blood, you do not have life within you....For my flesh is true food, and my blood is true drink..."
As a result of this, many (of) his disciples returned to their former way of life and no longer accompanied him...
John, Ch. 6

I got lost with the tides. More confirmation?

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If I could see the algorhythm, and the numbers you used, I could show you where the error occurred.


First, you have to keep in mind that the Earth's rotation is getting slower, but the rate of slowing (a rate of a rate) is growing exponentially smaller.

If the rate of slowing were constant, that would violate the Law of Conservation of Angular Momentum as well as the Law of Rotational Inertia (if your calculations involved a constant rate of slowing, then that is where the error occurred).

The reason why the rate of slowing is growing exponentially smaller is due to the fact that the moon is getting further away. To illustrate this, imagine you are holding a dumbbell. There is a weight on both sides of the bar. You can put your hand between the weights and rotate it about it's Normal Axis. If you increase the distance between two weights, you cannot rotate the system about its axis as easily.

The earth's rotation is slowing at a rate of 0.005 seconds per year per year (at its current rate). This extrapolates to the earth having a 14-hour day 4.6 billion years ago, which is entirely possible. (This extrapolation takes into account of the potential Moon's mass.)

Keep in mind, the the rate at which the earth slows today is higher than average because the present rate of spin is in resonance with the back-and-forth movement of the oceans. What this means is that the earth is not a fixed system. In Physics, the oceans effectively make the earth an Open Inertial body. This means the Center Of Gravity between the Earth-Moon system is constantly shifting about, which explains not-so-constant spin of the Earth.

This information is verified via Empiricism because we know the Fossil rugose corals preserve daily and yearly growth patterns and show that the day was about 22 hours long 370 million years ago, in rough agreement with the 22.7 hours predicted from a constant rate of slowing (a non-constant rate of slowing puts the length of one Earth Rotation at about 22 hours).


I can only assume in the calculations involved were incorrect, did not take into accordance enough variables, and did not involve itself in Elementary Physics. (And really, why does it matter so much that the Earth be 6000 years old?)

lol just be a yec ist like me, that'll solve all your problems.

If I may be allowed to paraphrase:

"Just shut your mind off like me, that'll solve all your problems. You can just blindly accept what your Church Creation Champ (CCC) tells you and call everyone else a heretic, it's very simple!"

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Bushido216

congradulates Bushido216 for not flaming. God bless you

Originally Posted by Vegan Charity

The earth's rotation is slowing at a rate of 0.005 seconds per year per year (at its current rate). This extrapolates to the earth having a 14-hour day 4.6 billion years ago, which is entirely possible. (This extrapolation takes into account of the potential Moon's mass.)

Chilehed, this is the essential part of all the posts. If you are getting a different answer than this, then
1. Your viscous damping model is wrong.
2. Your constants in your equations are wrong.
3. You made some arithmetic errors.

I'm willing to bet it's a combination of 1 and 2.

This information is verified via Empiricism because we know the Fossil rugose corals preserve daily and yearly growth patterns and show that the day was about 22 hours long 370 million years ago, in rough agreement with the 22.7 hours predicted from a constant rate of slowing (a non-constant rate of slowing puts the length of one Earth Rotation at about 22 hours).

Nice data!

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