# Thread: On Einstein's explanation of the invariance of c

1. Originally Posted by Neddy Bate
Yes, I understand. You took the existing definition of a meter, and added your own stipulation that it only holds true in the absolute rest frame. There is no such stipulation in the real definition of a meter.
http://en.wikipedia.org/wiki/Meter

The metre (or meter), symbol m, is the base unit of length in the International System of Units (SI). Originally intended to be one ten-millionth of the distance from the Earth's equator to the North Pole (at sea level), its definition has been periodically refined to reflect growing knowledge of metrology. Since 1983, it is defined as the distance travelled by light in vacuum in 1⁄299,792,458 of a second.[1]

The distance traveled by light, not the time it takes light to traverse a meter stick!!!

2. Originally Posted by Motor Daddy
http://en.wikipedia.org/wiki/Meter

The metre (or meter), symbol m, is the base unit of length in the International System of Units (SI). Originally intended to be one ten-millionth of the distance from the Earth's equator to the North Pole (at sea level), its definition has been periodically refined to reflect growing knowledge of metrology. Since 1983, it is defined as the distance travelled by light in vacuum in 1⁄299,792,458 of a second.[1]

The distance traveled by light, not the time it takes light to traverse a meter stick!!!
Where does it say anything about "absolute rest"?

3. Originally Posted by Neddy Bate
Where does it say anything about "absolute rest"?
Where does it say anything about an object???

4. I'll repeat it again.

The distance traveled by light, not the time it takes light to traverse a meter stick!!!

5. Originally Posted by Motor Daddy
Where does it say anything about an object???
That definition of a meter can hold true on a bus going 60 MPH. All you need is a vacuum, some light, and a very accurate clock.

Anyway, I've got to run now. But please consider what I said in post #519, I really think that will help us reach an agreement.

6. Originally Posted by Neddy Bate
That definition of a meter can hold true on a bus going 60 MPH. All you need is a vacuum, some light, and a very accurate clock.

Anyway, I've got to run now. But please consider what I said in post #519, I really think that will help us reach an agreement.
That definition can stand anywhere, as light travels independently of objects. Einstein DID NOT grasp that concept, for if he did, he would be in agreement with me.

7. Originally Posted by Neddy Bate
I can. Remember when RJBeery asked you to measure the width of the continent using light signals? These were your steps:

1. Synchronize the clocks at each coast by pulling strings from the center of the continent

2. Measure the one-way travel times for light in both directions

3. Calculate the absolute speed of the country

4. Calculate the width of the country.

Well, in relativity, they do things a little differently than that. It goes something like this:

A. Synchronize the clocks at each coast by sending light signals back and forth between the clocks

B. Measure either the round-trip or one-way travel times for light

C. Calculate the width of the country.

You see, "A" causes the one-way travel times of light to always be the same in either direction. That is why "B" can use either the round-trip times. or the one-way times. And then "C" lets you can calculate the width of the country without knowing its speed. It's not that different from your method, except there is no such thing as absolute simultaneity, and there is no such thing as absolute speed. With this method, the light-based definition of a meter holds true in all inertial reference frames.
You can not calculate the width of the country without knowing its speed.

Show me an example such as my country example, using Einstein's methods, that you find the width of the country without knowing the speed? That is impossible, as I described before, light can take different amounts of time to travel an object's length, depending on the speed of the object.

It is why Einstein can not tell you the speed of the box, or the width of the country from within the box.

8. Originally Posted by Motor Daddy
You can not calculate the width of the country without knowing its speed.

Show me an example such as my country example, using Einstein's methods, that you find the width of the country without knowing the speed? That is impossible,
Easy, you place a mirror at the far end of the country, you send a pulse of light towards the mirror. You start a clock when you send the pulse, you stop the clock when the pulse arrives back. The width of your country is:

W=c*T/2

as I described before, light can take different amounts of time to travel an object's length, depending on the speed of the object.
Not in the frame attached to the object (your "country"). In that frame, the time it takes to go E-W is equal to the time needed to go W-E.

It is why Einstein can not tell you the speed of the box, or the width of the country from within the box.
But you can. This is why the Nobel committee has invited both Einstein and Galilei to your Nobel prize awarding next year.

9. Originally Posted by Tach
Easy, you place a mirror at the far end of the country, you send a pulse of light towards the mirror. You start a clock when you send the pulse, you stop the clock when the pulse arrives back. The width of your country is:

W=c*T/2
Wrong again, Tach, as round trip light travel time only gets the length right if the country has a zero velocity. You can not find the length using round trip time.

Originally Posted by Tach
But you can. This is why the Nobel committee has invited both Einstein and Galilei to your Nobel prize awarding next year.
Like I said, just make sure the headlines read, "Einstein's SR renamed to BS." That and send Bank of America certified checks to me. I don't want to be in the same category as Gore.

10. Ah whatever!

If I was beyond the event horizon of the quasar in the center of M87, and M87 was inside a box, how could I calculate the speed of the box?

11. Originally Posted by Motor Daddy
Wrong again, Tach, as round trip light travel time only gets the length right if the country has a zero velocity. You can not find the length using round trip time.
Sorry to burst your bubble, this method has been used successfully from the 1800's, even before your so much hated Einstein.

Like I said, just make sure the headlines read, "Einstein's SR renamed to BS." That and send Bank of America certified checks to me. I don't want to be in the same category as Gore.
I did. Einstein and Galilei mummies will be delivering your prize.

12. Originally Posted by Tach
Sorry to burst your bubble, this method has been used successfully from the 1800's, even before your so much hated Einstein.
...and in hundreds of years, nobody ever figured out how fast the box was going. Incredible!! Can you imagine how they would feel knowing that it was as simple as second grade math, and yet they still couldn't figure it out? Sure you can!

Originally Posted by Tach
I did. Einstein and Galilei mummies will be delivering your prize.
Cool!

13. Originally Posted by Motor Daddy
...and in hundreds of years, nobody ever figured out how fast the box was going.

But you did! Even if they kept you inside the pitch dark box!

Incredible!! Can you imagine how they would feel knowing that it was as simple as second grade math, and yet they still couldn't figure it out? Sure you can!
They feel like being entertained.

14. Originally Posted by Tach
Duh, when they were giving out brains you were out on an errand.
Now I would like to understand if light travels in straight lines as you contend in ECEF with MMX, does that mean it does not in ECI with no sagnac as proven in ECI?
This was my simple minded question.

This mean you can not answer it. I would not if I be you.

15. Originally Posted by chinglu
This was my simple minded question.
Yes.

16. I am the only one who understands the concept of light traveling independently of objects (such as a meter stick), hence I am the only one who has ever been able to measure the velocity of a box in space from within the box.
You now rank very highly on the crank index.

You're correct, I am the only one who understands the concept of light traveling independently of objects (such as a meter stick), hence I am the only one who has ever been able to measure the velocity of a box in space from within the box.
Can you please give me a step-by-step process showing how you can determine the velocity of a box using only experiments inside the box?

Thanks.

Tach does not understand how light travels, as evident by him saying light always takes the same amount of time to traverse a meter stick, regardless of its motion. That is absurd!
That remains to be seen. I'll wait for your method before commenting.

18. I think MD hasn't put together that the metre is defined in terms of an interval of time. The time he's quoted above is also defined in terms of the distance light travels. Both time and distance are precisely defined over a real interval, in terms of light traveling through a vacuum.

To elaborate: it means that distance (the metre) is defined as a number of transitions--wavelengths--whereas time is defined by the frequency of the transitions--an oscillator. Conventionally the emitting particle is in a "stationary frame". So choosing an oscillator corresponds to choosing a rest frame.

19. Originally Posted by James R

Can you please give me a step-by-step process showing how you can determine the velocity of a box using only experiments inside the box?

Thanks.
1. You synchronize two clocks as such that they read the same time, simultaneously, as they would in a single time zone. I've given numerous ways of doing this in this thread. I'm sure technology has a better way of doing this, that's fine, the more accurate the better. I do not claim that you can measure time with 100% accuracy, as that is impossible for anyone to do. I am using theoretical clocks that are 100% accurate, and they are 100% synchronized with absolute simultaneity. Again, the more accurate and simultaneous the clocks read, the more accurate your measurements will be. There is always a margin of error due to our imprecise equipment. Just remember, by definition, you can not separate the distance light travels from the elapsed time of the light travel. It is simultaneous in that regards, as are two lights meeting. By definition, the lights each traveled the same distance in the same elapsed time, simultaneously.

2. The synchronized clocks are a distance apart from each other. You will measure the length of that distance between the clocks.

3. You send a light signal from one clock towards the other clock and record the time the light signal was sent.

4. You record the time the light signal arrives at the other clock.

5. You subtract the start time from the arrival time to find the amount of elapsed time that the light signal took to go from one clock to the other.

6. You perform steps 3-5 in the opposite direction.

7. You now have the one-way travel times in each direction. You know the speed of light is 299,792,458 m/s, by definition. You therefore know how far light traveled in each direction by simply multiplying the elapsed time by 299,792,458. So for example, if you measured .1 seconds in one direction, and you measured .2 seconds in the opposite direction, light traveled 29,979,245.8 meters in one direction, and 59,958,491.6 meters in the opposite direction.

8. 59,958,491.6-29,979,245.8=29,979,245.8 meters. That means the box traveled 29,979,245.8 meters in .3 seconds, its velocity is 99,930,819.33 m/s.

9. The box traveled 99,930,819.33 m/s for .2 seconds in one direction, so the box traveled 19,986,163.866 meters in .2 seconds, and the light traveled 59,958,491.6 meters in .2 seconds. That means the distance between the clocks is 59,958,491.6-19,986,163.866=39,972,327.734 meters.

20. Originally Posted by Motor Daddy

So for example, if you measured .1 seconds in one direction, and you measured .2 seconds in the opposite direction, light traveled 29,979,245.8 meters in one direction, and 59,958,491.6 meters in the opposite direction.
Since you are measuring the SAME distance in both directions, light cannot travel ".1s in one direction" and ".2s in the opposite direction".

You flunked.

8. 59,958,491.6-29,979,245.8=29,979,245.8 meters. That means the box traveled 29,979,245.8 meters in .3 seconds, its velocity is 99,930,819.33 m/s.
Nope, since this is based on the error at the previous point. You will need to take this class over. Or, even better, sit in your dark box and take a break from posting nonsense.