Why in the world would Einstein suggest....

@layman,

layman wrote:

Quote:
The diagram is a lateral, cross-sectional view of an The diagram is a lateral, cross-sectional view of an imagined 3rd-party, omnisicent view

I don't think that's what's being presented at all. There is no "cross-sectional view of an imagined 3rd-party, omnisicent view."

I think wiki itself makes this clear. It also says this:

Quote:
From the frame of reference of a moving observer traveling at the speed v relative to the rest frame of the clock (diagram at lower right), the light pulse traces out a longer, angled path

It's the "longer, angled path" that I was calling "zig-zag."

There are two diagrams. In the first, there are both perceivers A and B. In the second, there are both mirrors A and B. How could a single oberver see both at once, whichever diagram you choose?

1 Reply

@FBM,

There are just two observers in the wiki example (who are Jack and Jill in Fowler's presentation. Each measures a different thing. Per wiki:

1. "Observer at rest (Jack) measures time 2L/c"

2. "Observer moving parallel relative to setup (Jill) measures longer path and thus, with same speed of light c, measures longer time 2D/c > 2L/c."

0 Replies

@FBM,

Quote:

There are two diagrams. In the first, there are both perceivers A and B. In the second, there are both mirrors A and B. How could a single oberver see both at once, whichever diagram you choose?

Maybe reading Fowler's presentation would help you. Jack has one clock (his own) which he is comparing to Jill's clock (which is moving). Jack can "see" them both.

1 Reply

@layman,

Fowler:

Quote:

To be specific, imagine Jack standing on the ground with his light clock next to a straight railroad line, while Jill and her clock are on a large flatbed railroad wagon which is moving down the track at a constant speed v. Jack now decides to check Jill’s light clock against his own.

http://galileoandeinstein.physics.virginia.edu/lectures/srelwhat.html

0 Replies

Yep. My mistake with the Wiki diagrams. I should've looked more carefully. Scratch what I said about that.

And that's a good indication that it's time for me to turn my brain off for a while and let it reboot. 10 p.m. here and time to watch a movie or youtubes of people beating the **** out of each other or something. There's been a lot of water under the bridge today.

1 Reply

@FBM,

OK. catch ya later, FBM.

1 Reply

@layman,

0 Replies

@layman,

Quote:

It's like saying the rules of logic simply don't apply to anything involving SR.

That's assuming that the rules of the universe are logical and predictable at all levels. It is possible to have logical rules in place for certain things under limited circumstances. To require that all circumstances be logical and predictable goes against current physics. To have it always predictable would mean you have discovered the unified theory.

0 Replies

@layman,

Quote:

It will not help to say "both are correct." They can't both be correct in any meaningful way. At least one of them must be mistaken.

You assume that only one can be correct. Why is your assumption better than the assumption that light travels at the same speed in all inertial frames?

1 Reply

@layman,

Quote:

Keep in mind that the whole premise is that there REALLY IS relative motion between the two. Therefore the whole premise NECESSARILY implies that they cannot BOTH be at rest.

Actually they are both at rest since each sees their own inertial frame as at rest. You assume there is only one reference point with only one observer.

2 Replies

@parados,

Simply stated, they're at rest if they don't move. We're talking about human observati0n.

0 Replies

@parados,

Quote:

Actually they are both at rest since each sees their own inertial frame as at rest. You assume there is only one reference point with only one observer.

Let's assume there are 50 billions reference points (50 billions objects, all moving inertially but each going at a different speed than the others). All 50 billion "assume" that they are at rest. Are they ALL right? So nobody's moving at all, really?

How does a "frame of reference" change your speed?

Let's stop all the speculation and PUT THIS TO A TEST.

Two clocks. Both read 12:00 and both are at a naval station in Washington D.C.

One clock is taken aboard a plane, the other is not moved at all.

The plane takes off for a flight, then returns 6 hours later. When it returns the clock which went nowhere now reads 6:00. Will the clock which went on the plane trip read:

1. Also 6:00, the same as the other?
2. Earlier than 6:00 (say 5:55)?
3. Later than 6:00 (say 6:05) or
4. EACH CLOCK WILL READ EARLIER THAN THE OTHER?

If you don't pick #4, then shut up about "each being slower than the other." If you DO pick #4, please explain just how THAT could possibly work, OK?

Keep in mind that at 3:00, according to the stationary clock, the clock on the plane is in the air and going at a different speed than the clock on the ground. It is allegedly "seeing" the naval clock run slower than it. Also keep in mind that the clock on the plane also "claims" that IT is not moving, but that the clock at the naval station IS moving.

2 Replies

@layman,

You are begging the question by only telling time from one reference point and then insisting that reference point is the only one we can use.

1 Reply

@layman,

layman wrote:

that a man on a moving train does NOT know he is moving relative to the earth's surface, and not vice versa? Who in the world would get on a train, feel himself being accelerated, and then, once a uniform speed has been attained, conclude that the trees, stop signs, houses, etc. are moving past him while he remains completely motionless. Isn't this rather absurd?

Who would ask the conductor if Chicago stops here?

Yet this presumption is the sine qua non of special relativity theory, isn't it?

Well it comes down to how you view everything. The point he was making is similar to the fact that our galaxy is traveling through space toward a fixed point in the Hydra constellation at 1.34 million miles per hour. This velocity is mind boggling. Can you even imagine a million miles per hour?

Yet from our perspective we don't even think we are moving through space but the fact is the Earth NEVER touches the same points in space ever even though it orbits a star, but that star is also moving around the galaxy's center and the entire galaxy itself is moving on a tangent not just rotating.

So are you even aware of this fact or did you think we were for the most part stationary?

1 Reply

@parados,

Have an answer to the question, Parados? Hint: This experiment has been done, and the answer is known:

Quote:

1. Also 6:00, the same as the other?
2. Earlier than 6:00 (say 5:55)?
3. Later than 6:00 (say 6:05) or
4. EACH CLOCK WILL READ EARLIER THAN THE OTHER?

If you don't pick #4, then shut up about "each being slower than the other." If you DO pick #4, please explain just how THAT could possibly work, OK?

Is your answer #4?

2 Replies

@Krumple,

Quote:

The point he was making is similar to the fact that our galaxy is traveling through space toward a fixed point in the Hydra constellation at 1.34 million miles per hour. This velocity is mind boggling. Can you even imagine a million miles per hour?

Yes, and no

Yes: It is acknowledged by modern astrophysicists that, yes, we are moving at the rate of over a million miles an hour (as determined by comparisons made with the CMB).

No: That is NOT Al's "point' and it is not what Al was saying in formulating the "relativity of simultaneity" in SR. SR PROHIBITS us from considering ourselves to be in motion and DENIES that we could ever, under any circumstances, know we were moving. Then again, it contradicts itself on this very point, so.....

1 Reply

@layman,

Silly; it's all those times at one place or another. For drinkers, it's always 5 o'clock someplace on this planet - morning or night.

A frame a reference only applies to the individual who needs to be someplace at a given time. That's not science; it's common sense.

1 Reply

@cicerone imposter,

Quote:

A frame a reference only applies to the individual who needs to be someplace at a given time. That's not science; it's common sense.

Right, and the science of physics is not psychology. Nor does physics serve as the personal secretary for all "who need to be someplace at a given time."

0 Replies

@parados,

Quote:

You assume that only one can be correct. Why is your assumption better...

1. The guy on the airplane says that he is motionless, that Washington D.C. is moving, and that Washington's clock is running slower.

2, The guy in Washington says that he is motionless, that the airplane is moving, and that the airplane's clock is running slower.

Answer the question: Do YOU contend that "both are correct?"

1 Reply

@layman,

Of course the answer is known because we are always telling time from one reference. How many times do I have to explain that to you?

1 Reply

Why in the world would Einstein suggest....

Related Topics

Quick Links

My Account

able2know