Question for the Science Guys (Jewett, Dr. Dave)

[Dawgie]

Think of it as trying to swim across a river. The slower you swim the farther downstream you will be when you reach the other side.

Steve

Is this with the outgoing tide or incoming tide?

 

[Jal]

Yeah, I watch the Science Channel all the time. The moment they get into the physics of space & time, my brain hurts. I actually had to look up what the moon is doing and it's listed as moving away from the Earth at a rate of 38 mm per year. I can't say I understand it. That's what I found.

Though a surprising sleight of hand (for gravity), you don't have to get into General Relativity to explain it. The pictures in this article do it pretty well:

http://www.talkorigins.org/faqs/moonrec.html

Essentially, the center of mass of the earth is shifted slightly off the line of centers between the moon and earth by the tidal mass of water. This pulls the moon forward, increasing its orbital velocity (ie, the moon takes off along the tangent line).

What's more, there are physicists that talk about "missing gravity". They claim gravitational force should be much much greater and attribute it to string theory (multiple dimensions) or something like that. I'm lost at that point and can only say that casual observations about space are only sometimes correct and usually that's just a coincidence.

Are you a closet googan or something? As you point out, the vast majority of the universe seems to made of some unknown substance...which is a very curious state of affairs for modern science. The known stuff just doesn't produce enough gravitational pull to keep everything together as much as is observed. But they're talking about a very large scale of distance, such as across super clusters of galaxies. On much smaller scales, such as around the earth and moon for instance, the known quantities of mass do account for motions very well.

Jim

 

[Jude Rosenstock]

Though a surprising sleight of hand (for gravity), you don't have to get into General Relativity to explain it. The pictures in this article do it pretty well:

http://www.talkorigins.org/faqs/moonrec.html

Essentially, the center of mass of the earth is shifted slightly off the line of centers between the moon and earth by the tidal mass of water. This pulls the moon forward, increasing its orbital velocity (ie, the moon takes off along the tangent line).

Are you a closet googan or something? As you point out, the vast majority of the universe seems to made of some unknown substance...which is a very curious state of affairs for modern science. The known stuff just doesn't produce enough gravitational pull to keep everything together as much as is observed. But they're talking about a very large scale of distance, such as across super clusters of galaxies. On much smaller scales, such as around the earth and moon for instance, the known quantities of mass do account for motions very well.

Jim

Thanks for the link. I'll take a closer look at it when I get home.

I can't say I know a lot about this stuff. I CAN say there's a lot I don't know and every time I study it a little, I get a better sense of what it is I don't know.

 

[Jerry Forsyth]

two bullets

And furthermore, if you drop a bullet at the same time that you fire a bullet on a level plane, it is the bullet you fire that convinces the other gentleman that you do not really owe him that money.

 

[philw]

If any of you watched the old Dennis Miller show that was on HBO for years, you may have noticed in the opening sequence six balls that looked like little "Earths" going into six pockets on a pool table. The song "Everybody Wants To Rule The World" was playing in the background while this shot was being made.

Well, I made that shot for Dennis. It was done by using six cue balls painted to look like planet Earth. And it was made on a movie prop "pool table". This table had a plywood surface covered with plain green cloth. To say it rolled off is a massive understatement. The balls literally rolled everywhere in every direction.

I tried the shot a few times and told them it was nearly impossible to make this shot. Balls were rolling everywhere. I said there may be one way for me to do it. I have to shoot REAL hard! That way there is little, if any, roll off before they reach the pockets. The Director said go ahead and try it. I shot it six times with full force and twice I made all six balls/Earths. And I mean I hit it really hard!

Just like that, we were done with my segment. When it aired on TV, they slowed down the film speed considerably, so you could see the balls rolling into the holes. Ah, the wonders of Hollywood! Of course, they substituted Dennis for me, and made it look like he made the shot. I enjoyed hanging out with Dennis that day. He's a cool guy and very bright.

Just goes to show you how two people can be on opposite sides of the political spectrum and still get along and have respect for each other.
I too agree that Dennis is exceptionally smart and terrifically funny with great insight. I think you're pretty cool too Jay. Philw

 

[DoubleA]

It's actually gravity that's pulling the moon away - quite the trick from mother nature.

Jim

Actually gravity is pulling at the moon which keeps it in orbit as inertia attempts to pull it out of orbit. Because of it's speed it is able to keep from being pulled into the earth at the current time and is actually moving slightly away. however, the velocity is decreasing and will eventualy slow to the point where gravity will be stronger than inertia and it will move toward the earth instead of away. when this happens, the events I previously described will occur,according to most all renowned astromomers. There are however conflicting theories on this. Bottom line is no one really can know for sure. What ever happens will not effect us or our descendants any way.

 

[Jal]

Actually gravity is pulling at the moon which keeps it in orbit as inertia attempts to pull it out of orbit. Because of it's speed it is able to keep from being pulled into the earth at the current time and is actually moving slightly away.

No argument here. But the mechanism that's causing it to move away is gravity, to my understanding. One way of looking at it is that the tides slow the earth's rotation. Conservation of angular momentum then tells us that this has to be made up in some way, ie, by the moon spinning faster, or the earth/moon orbiting velocities increasing. The article I linked to earlier shows how gravity acts to speed up the moon.

however, the velocity is decreasing and will eventualy slow to the point where gravity will be stronger than inertia and it will move toward the earth instead of away. when this happens, the events I previously described will occur,according to most all renowned astromomers.

I'll have to do more reading. Maybe you have a link?

But from what I've read thus far, and generally knew, the moon has always been receding. And according to the article, this was happening at a slower pace in ancient times because of the existence of just one continent, which resulted in less resistance to tidal flows (the earth didn't push the tidal mass ahead as much).

Jim

 

[DoubleA]

No argument here. But the mechanism that's causing it to move away is gravity, to my understanding. One way of looking at it is that the tides slow the earth's rotation. Conservation of angular momentum then tells us that this has to be made up in some way, ie, by the moon spinning faster, or the earth/moon orbiting velocities increasing. The article I linked to earlier shows how gravity acts to speed up the moon.

I'll have to do more reading. Maybe you have a link?

But from what I've read thus far, and generally knew, the moon has always been receding. And according to the article, this was happening at a slower pace in ancient times because of the existence of just one continent, which resulted in less resistance to tidal flows (the earth didn't push the tidal mass ahead as much).

Jim

This is all true. The theory is that once the rotations match, the expanding orbit ceases to expand and begans to contract. If the moon could in fact reach Roche's limit(radius) is open to debate, it once was the prevailing theory. This can only happen if the earth-moon system could outlive the solar system(not supposed to Happen). What I was describing was a prediction based on this assumption. I suppose this discussion would be more suited to the NPR. We may have moved to far from the thread.

 

[Deadon]

Surprised many don't get it.

The tables contact with the ball creates another vector. If the table is not level then the vector, from the table, is not on the exact bottom of the ball, but slightly off to the high side. When you combine that vector with the one from gravity, you come up with the one that makes it curve. That final vector acts on the inertia of the CB going down the table. The more speed on the CB, the more inertia, the less effect the other resultant vector has(less curve) on the CB.

The bullet idea doesn't apply, because the CB is not falling only, but being held up by the table and being pushed to the side.

Tried to simplify it a little.

 

[softshot]

the vast majority of the universe seems to made of some unknown substance...which is a very curious state of affairs for modern science. The known stuff just doesn't produce enough gravitational pull to keep everything together as much as is observed.
Jim

thats the key point isn't it

of course it's been proven that light is a particle and a wave

particles have mass

therefore light has mass

therefore all the light sent in all directions from every star in the universe has mass


and apparently maintains that same mass throughout its journey from the star..

so if you imagine a sphere and at any point on the surface of that sphere is the farthest distance that the original light from the big bang has traveled..

and add up the mass of all the light particles in that sphere...


you find that the missing matter in the universe is actually light... dark matter is light.... kind of funny that the best minds in the world named it wrong...

but what do I know... I'm just a pool player..

 

[DoubleA]

thats the key point isn't it

of course it's been proven that light is a particle and a wave

particles have mass

therefore light has mass

therefore all the light sent in all directions from every star in the universe has mass


and apparently maintains that same mass throughout its journey from the star..

so if you imagine a sphere and at any point on the surface of that sphere is the farthest distance that the original light from the big bang has traveled..

and add up the mass of all the light particles in that sphere...


you find that the missing matter in the universe is actually light... dark matter is light.... kind of funny that the best minds in the world named it wrong...

but what do I know... I'm just a pool player..

Yes, and aren't we lucky that light only acts as matter when it is unobserved and acts as wave energy when it is observed basically.(doesn't this sound crazy?)