Why in the world would Einstein suggest....

@oralloy,

Quote:

Because one changed inertial frame of reference, and one didn't.

Exactly. Or, as Feynman put it (in more everyday terms) because moving clocks are the ones that run slow and the airplane clock was the one actually moving in this case.

0 Replies

@FBM,

FBM wrote:

Inertial reference frames are not accellerating, so why would accelleration matter?

When you accelerate, you change from one inertial frame of reference to another.

Once an object has changed inertial frames of reference, its point of view is no longer equal to an object that has not changed its inertial frame of reference.

2 Replies

@FBM,

FBM wrote:

I think we need the word "appear" in there. Like, "appear to speed up."

You are right it does come down to the point of reference. Appear may be a better word but in another way it actually occurs. Once you compare the result there is a discrepancy in clocks. Using my example, you arrived at work at 5:01pm but according to your boss you are late, not by a minute but far longer.

0 Replies

@FBM,

I

Quote:

think we need the word "appear" in there. Like, "appear to speed up."

Why? Once again:

Quote:

It has been verified in recent years by flying very accurate clocks around the world on jetliners and finding they register less time, by the predicted amount, than identical clocks left on the ground.

Where in that sentence should the word "appear" have been placed, FBM? "Apparently" finding....ya figure?

0 Replies

@oralloy,

Quote:

Once an object has changed inertial frames of reference, its point of view is no longer equal to an object that has not changed its inertial frame of reference.

Exactly. Because now it is the moving clock, and, as SR assures us, it is ALWAYS the moving clock which runs slow.

1 Reply

@Krumple,

Krumple wrote:

If Carl is right and Einstein, then you are wrong.

No. All three of us are correct.

Carl did oversimplify a bit though.

0 Replies

@layman,

layman wrote:

Quote:
Once an object has changed inertial frames of reference, its point of view is no longer equal to an object that has not changed its inertial frame of reference.

Exactly. Because now it is the moving clock, and, as SR assures us, it is ALWAYS the moving clock which runs slow.

Exactly and if you were traveling very fast but could in some way observe a stationary clock, it would appear to you to speed up.

1 Reply

@oralloy,

oralloy wrote:

FBM wrote:
Inertial reference frames are not accellerating, so why would accelleration matter?

When you accelerate, you change from one inertial frame of reference to another.

Once an object has changed inertial frames of reference, its point of view is no longer equal to an object that has not changed its inertial frame of reference.

My understanding is that the two clocks are already in two different inertial frames when the clock observations take place, so neither is accelerating. If you take Jack's clock to Jill's frame, it will read as if it had run slower while in Jack's frame, but once it's in Jill's frame, it'll be running normally again. Same happens if you take Jill's clock to Jack's frame. So, with neither frame being preferred, it seems to me that it makes perfect sense to say that both are running slower/faster than the other, as long as they remain in their own frames. I don't think it's a good idea to reject a result just because it's counter-intuitive.

3 Replies

@Krumple,

Quote:

Exactly and if you were traveling very fast but could in some way observe a stationary clock, it would appear to you to speed up

True that, Krumps, but don't EVER tell SR that.

1 Reply

@FBM,

Quote:

...it seems to me that it makes perfect sense to say that both are running slower/faster than the other, as long as they remain in their own frames. I don't think it's a good idea to reject a result just because it's counter-intuitive.

You seem to be forgetting one thing, FBM, to wit: Fowler CLEARLY says they are moving relative to each other. Is it POSSIBLE, at all, for both to be at rest, under those circumstances? Notice he does NOT say that they "really are" each moving slower than the other, only that they "appear" to be.

Every physicist I've ever seen weigh in on the matter, starting with Al himself, says that it CAN'T be the case that "each clock is slower than the other."

1 Reply

@layman,

layman wrote:

Quote:
Exactly and if you were traveling very fast but could in some way observe a stationary clock, it would appear to you to speed up

True that, Krumps, but don't EVER tell SR that.

Thankx however; it has strange implications. Would it not mean that a photon isn't really moving at the speed of light but actually faster? Because we calculate it's velocity from a stationary position where as if you were riding on the photon time would be slowed down meaning you arrive at the target destination long before the person timing you saw you pass the finish line.

0 Replies

@layman,

If they're moving, then they're not at rest. Not sure where you're going with that.

Anyway, I'm thinking I need to bow out of the discussion. I'm not getting much from it, nor contributing much to it.

3 Replies

@FBM,

FBM wrote:

My understanding is that the two clocks are already in two different inertial frames when the clock observations take place, so neither is accelerating. If you take Jack's clock to Jill's frame, it will read as if it had run slower while in Jack's frame, but once it's in Jill's frame, it'll be running normally again. Same happens if you take Jill's clock to Jack's frame. So, with neither frame being preferred, it seems to me that it makes perfect sense to say that both are running slower/faster than the other, as long as they remain in their own frames. I don't think it's a good idea to reject a result just because it's counter-intuitive.

Yes. That is correct.

0 Replies

@FBM,

FBM wrote:

If they're moving, then they're not at rest. Not sure where you're going with that.

Read "at rest" to mean "at rest with regard to their original inertial frame of reference".

1 Reply

@FBM,

I mean, like just think about it.

Let's say it's true that each clock is running slower than the other. Let's say clock A reads 6:00, when they meet back up. What would clock B read?

2 Replies

@layman,

layman wrote:

I mean, like just think about it.

Let's say it's true that each clock is running slower than the other. Let's say clock A reads 6:00, when they meet back up. What would clock B read?

If clock A were the one moving it would be behind clock B that was stationary. The difference in time is dependent upon the velocity of clock A and for how long it remained at that velocity. The longer it remains at a high velocity the larger the difference in comparative time between them.

0 Replies

@oralloy,

Quote:

Read "at rest" to mean "at rest with regard to their original inertial frame of reference".

You mean, "at rest" with respect to themselves? Isn't that ALWAYS true? Is that really "saying" anything? If I shoot a bullet out of a gun at the rate of 4,000 feet per second, it's still at rest "with respect to itself," isn't it?

1 Reply

@layman,

layman wrote:

I mean, like just think about it.

Let's say it's true that each clock is running slower than the other. Let's say clock A reads 6:00, when they meet back up. What would clock B read?

Depends on which frame they meet in.

1 Reply

@FBM,

Quote:

If they're moving, then they're not at rest

Maybe one is, but it couldn't possibly be true that BOTH are at rest, true that.

0 Replies

@layman,

layman wrote:

You mean, "at rest" with respect to themselves? Isn't that ALWAYS true? Is that really "saying" anything? If I shoot a bullet out of a gun at the rate of 4,000 feet per second, it's still at rest "with respect to itself," isn't it?

Anything that accelerates, changes to a different inertial frame of reference.

Once the bullet accelerates it will no longer be in its original inertial frame of reference.

1 Reply

Why in the world would Einstein suggest....

Related Topics

Quick Links

My Account

able2know