The Relativity of Simultaneity

[AlexG]

I take it your are referring to me. FYI I have conceded I was wrong twice today and I can spell conceded.

Actually, no, I was referring to MD.

And once you've descended to pointing out spelling errors, you're close to hitting bottom.

 

[quantum_wave]

Actually, no, I was referring to MD.

And once you've descended to pointing out spelling errors, you're close to hitting bottom.

It was an aside, like a little bonus. Unfortunately the motivation for my response was an error in my perception. In my defense I have been hogging the thread and I thought you were just being one of the smart guys by ripping me for standing in there in the heat that MD is taking. My mistake.

 

[Emil]

I had some time available and I found these, about synchronization of GPS clocks and the clocks on Earth.

Correcting a GPS receiver clock:

Correcting a GPS receiver's clock
One of the most significant error sources is the GPS receiver's clock. Because of the very large value of the speed of light, c, the estimated distances from the GPS receiver to the satellites, the pseudoranges, are very sensitive to errors in the GPS receiver clock; for example an error of one microsecond (0.000 001 second) corresponds to an error of 300 metres (980 ft). This suggests that an extremely accurate and expensive clock is required for the GPS receiver to work. Because manufacturers prefer to build inexpensive GPS receivers for mass markets, the solution for this dilemma is based on the way sphere surfaces intersect in the GPS problem.
It is likely that the surfaces of the three spheres intersect, because the circle of intersection of the first two spheres is normally quite large, and thus the third sphere surface is likely to intersect this large circle. It is very unlikely that the surface of the sphere corresponding to the fourth satellite will intersect either of the two points of intersection of the first three, because any clock error could cause it to miss intersecting a point. However, the distance from the valid estimate of GPS receiver position to the surface of the sphere corresponding to the fourth satellite can be used to compute a clock correction.

GPS,Timekeeping and leap seconds:

Timekeeping and leap seconds
While most clocks are synchronized to Coordinated Universal Time (UTC), the atomic clocks on the satellites are set to GPS time (GPST; see the page of United States Naval Observatory). The difference is that GPS time is not corrected to match the rotation of the Earth, so it does not contain leap seconds or other corrections that are periodically added to UTC. GPS time was set to match Coordinated Universal Time (UTC) in 1980, but has since diverged. The lack of corrections means that GPS time remains at a constant offset with International Atomic Time (TAI) (TAI - GPS = 19 seconds). Periodic corrections are performed on the on-board clocks to keep them synchronized with ground clocks.[73]

The GPS navigation message includes the difference between GPS time and UTC, which as of 2011 is 15 seconds because of the leap second added to UTC December 31, 2008. Receivers subtract this offset from GPS time to calculate UTC and specific timezone values. New GPS units may not show the correct UTC time until after receiving the UTC offset message. The GPS-UTC offset field can accommodate 255 leap seconds (eight bits) that, given the current period of the Earth's rotation (with one leap second introduced approximately every 18 months), should be sufficient to last until approximately the year 2300.

 

[Pete]

Keep researching, Emil. Check your theory against facts.
How much and how often should GPS satellite (not receiver) clock correction should be required, according to your understanding?
How much correction is required in practice?

Also, from earlier:

This means that different reference frames each has its own reality?

No. Each reference frame has its own standard of measurement.
But measurements made in all reference frames will agree on what happens at E.

If one measurement of a distance is 1 inch, and another measurement of the same distance is 25.4mm, does that mean one of them must be incorrect?

With this I agree.

With what do you agree?

Length is a basic physical dimension. (It is a quantity.)
Dimensional analysis,Percentages and derivatives:

So length is measured with a standard. (And not by speed.)This standard may be different meter, foot, miles, nautical miles, etc.
If we choose as a standard the meter then this fits 149.60 × 10 ^ 9 times between Earth and Sun.
Therefore we say that the distance between Earth and Sun is 149.60 × 10 ^ 9 m.
You say that this standard fit differently between Earth and Sun, depending on different reference frames?

Yes, that is correct. If you choose a different reference standard, you will measure a different distance between Earth and Sun.

That is why a measurement is useless unless it's reference standard is also known.

 

[RJBeery]

@Pete, QW and Emil: I gave MD a real world counter-example to his theory long ago...does a radio station's frequency change depending upon which direction the transmitter resides from the receiver? This is testable by any one of us with no reliance on such abstract concepts as GPS, muon decay, atomic clocks on jets, and other dubious "scientific" stuff.

 

[Motor Daddy]

@Pete, QW and Emil: I gave MD a real world counter-example to his theory long ago...does a radio station's frequency change depending upon which direction the transmitter resides from the receiver? This is testable by any one of us with no reliance on such abstract concepts as GPS, muon decay, atomic clocks on jets, and other dubious "scientific" stuff.

...and I answered your question correctly. The frequency doesn't change if the distance from the transmitter remains the same.

In the case of the lightening strikes at A and B, the midpoint observer is getting further away from the point in space that the strike occurred at A and closer to the point in space that the strike occurred at B, so the light travel times will be different for each.


In comparison, that would be like moving towards or away from the radio transmitter. One way is blue shifted and the other way is red shifted.

But we are not talking about multiple signals, we are talking about the first and only light signal, so there is no "red shift" or "blue shift."

I can do the same with a baseball. I throw it at you and time it. Say it takes 2 seconds to reach you while the distance between us remains the same the entire 2 seconds.

Then I throw it at you, but this time you run away from me as I release the ball. It takes more time and the ball travels a greater distance to reach you.

If I perform the test again, but this time you run towards me, the ball hits you in less than 2 seconds and travels a shorter distance.

There is no red shift or blue shift because there is only 1 ball being thrown at you, and the clock stops when it hits you.

 

[RJBeery]

To be honest, MD, I forgot that explanation. It's a rejiggering of light, to be sure. You're saying that the wavelength of light isn't related to "length" at all, but rather a function of "peaks per second". I'm way too tired right now to remember where our discussion went from here but I do recall thinking that it's an interesting idea if nothing else.

 

[Motor Daddy]

To be honest, MD, I forgot that explanation. It's a rejiggering of light, to be sure. You're saying that the wavelength of light isn't related to "length" at all, but rather a function of "peaks per second". I'm way too tired right now to remember where our discussion went from here but I do recall thinking that it's an interesting idea if nothing else.

If you related frequency to the motion of an internal combustion engine's crankshaft, frequency would be "RPM." As a matter of fact, you change the frequency of the output of an electric generator by changing the RPM of the engine.

 

[RJBeery]

MD, I'll have to review our last discussion because I recall being a bit disappointed when I concluded that your world cannot exist, due to the novelty of it (FTL travel producing time-reversal was one objection but there was something else...).

 

[Motor Daddy]

MD, I'll have to review our last discussion because I recall being a bit disappointed when I concluded that your world cannot exist, due to the novelty of it (FTL travel producing time-reversal was one objection but there was something else...).

There is no time reversal in my world. It is impossible to reverse time.

But, my method is not limited to measuring time at speeds above c, not that I'm saying any object could travel faster than light.

For instance, it is 12:00:00 in NY and it is 12:00:00 in Florida, say 1,000 miles apart from each other.

No matter how fast you travel from NY to Florida, you can not get there at or before 12:00:00. You can travel 1,000,000,000,000 times the speed of light, and you will not get there at or before 12:00:00.

That is because my clocks are absolutely sync'd, as they are in NY and Florida, and it takes time to travel, regardless of the speed at which you travel.

 

[RJBeery]

There is no time reversal in my world. It is impossible to reverse time.

But, my method is not limited to measuring time at speeds above c, not that I'm saying any object could travel faster than light.

For instance, it is 12:00:00 in NY and it is 12:00:00 in Florida, say 1,000 miles apart from each other.

No matter how fast you travel from NY to Florida, you can not get there at or before 12:00:00. You can travel 1,000,000,000,000 times the speed of light, and you will not get there at or before 12:00:00.

That is because my clocks are absolutely sync'd, as they are in NY and Florida, and it takes time to travel, regardless of the speed at which you travel.

Well maybe we need to clarify what I mean by time-reversal...if we're travelling away from a radio transmitter at an absolute velocity faster than c (which is not forbidden in your world), then we would be "overtaking" the previously emitted radiowaves, and receiving them in reverse. Sound from the radio and light would be "playing backwards" wouldn't they?

 

[Motor Daddy]

Well maybe we need to clarify what I mean by time-reversal...if we're travelling away from a radio transmitter at an absolute velocity faster than c (which is not forbidden in your world), then we would be "overtaking" the previously emitted radiowaves, and receiving them in reverse. Sound and light would be "playing backwards".

Again, time is not reversing. Time continues to tick.

If a car starts traveling from a start line at 60 MPH, and travels for 1 hour, and then you leave in a car from the start line traveling 500 MPH, you will catch and pass the 60 MPH car.

Do you imply that time reverses because the faster car catches and passes the slower car?

That slower car traveled for a time interval before you even started to travel. Otherwise, if you both left the starting line at the same time, you leaving at 500 MPH and him leaving at 60 MPH, you would always be in front of him.

 

[Emil]

Keep researching, Emil. Check your theory against facts.
How much and how often should GPS satellite (not receiver) clock correction should be required, according to your understanding?
How much correction is required in practice?

Also, from earlier:

No. Each reference frame has its own standard of measurement.
But measurements made in all reference frames will agree on what happens at E.


With what do you agree?


Yes, that is correct. If you choose a different reference standard, you will measure a different distance between Earth and Sun.

That is why a measurement is useless unless it's reference standard is also known.

Your answers are evasive and an attempt to overturning words. Many posts are simply neglect. For example, what connection exists between the different standards and length contraction? (And this is not due to English.)
But maybe I'm wrong and therefore I ask you clearly.

If you have with you the standard meter (this:

) and you travel with a velocity V between the Sun and Earth.
How many times fit this standard, which is with you, between the Sun and Earth is dependent on your speed V?

 

[RJBeery]

Actually as I sit here I'm starting to think that absolutely travelling faster than c is equivalent to falling past the Event Horizon of a BH. A growing ring of darkness encircling the visible world which shrinks to a point, as you look backwards.

Come to think of it, this effect would occur well before travelling at the speed of light, and I already covered it here. I'm disappointed that my brain has done such a poor job retaining that thread discussion - it was only 6 months ago!

 

[Emil]

@Pete, QW and Emil: I gave MD a real world counter-example to his theory long ago...does a radio station's frequency change depending upon which direction the transmitter resides from the receiver? This is testable by any one of us with no reliance on such abstract concepts as GPS, muon decay, atomic clocks on jets, and other dubious "scientific" stuff.

My position is here ,here and here .

 

[arfa brane]

That is because my clocks are absolutely sync'd, as they are in NY and Florida, and it takes time to travel, regardless of the speed at which you travel.

And that is one reason why Motor Daddy's universe doesn't correspond to the world everyone else is living in.

In the real universe, clocks have to be synchronised against other clocks; there is no such thing as "absolutely sync'd", which is just an idea. The idea does not have any real world examples, anywhere in the real universe.

That someone can keep insisting that something is real, when there is absolutely no evidence that it is, suggests some kind of mental problem.

Along the lines of: "If I jump off that building, I will be able to fly like Superman", kind of problem.

 

[quantum_wave]

And that is one reason why Motor Daddy's universe doesn't correspond to the world everyone else is living in.

In the real universe, clocks have to be synchronised against other clocks; there is no such thing as "absolutely sync'd", which is just an idea. The idea does not have any real world examples, anywhere in the real universe.

That someone can keep insisting that something is real, when there is absolutely no evidence that it is, suggests some kind of mental problem.

Along the lines of: "If I jump off that building, I will be able to fly like Superman", kind of problem.

I read the offending post several times and there is no reason to invoke mental disorders. I encourage you to read it and try to draw from it the intent. The absolute syncing of clocks was a concept associated with the intent to explain his position on time reversal, i.e. that in his view there is no time reversal.

 

[arfa brane]

The absolute syncing of clocks was a concept associated with the intent to explain his position on time reversal, i.e. that in his view there is no time reversal.

The concept of an absolutely synchronised clock implies the concept of an absolute interval of time to synchronise it, synchronisation is a process, so the concept leaves the question: how was the first clock synchronised "absolutely"? (??).

There is no such thing as an absolute interval of time, but there are arbitrary intervals of time--for instance, the interval it takes a particle such as a muon to decay.

Lastly, the laws of physics do not distinguish between the directions of time; there is no "movement" forwards or backwards, just a direction.

 

[quantum_wave]

The concept of an absolutely synchronised clock implies the concept of an absolute interval of time to synchronise it, synchronisation is a process, so the concept leaves the question: how was the first clock synchronised "absolutely"? (??).

There is no such thing as an absolute interval of time, but there are arbitrary intervals of time--for instance, the interval it takes a particle such as a muon to decay.

Lastly, the laws of physics do not distinguish between the directions of time; there is no "movement" forwards or backwards, just a direction.

I haven't followed the development of MD's concept of absolute sync'd clocks but from the importance being put on it, he must have been unscientific in some respect, and then wouldn't acknowledge that when challenged? On the surface, and for purposes of the point that he made to me as I questioned him, the absolute syncing of clocks is being give too much significance.

 

[origin]

I haven't followed the development of MD's concept of absolute sync'd clocks but from the importance being put on it, he must have been unscientific in some respect, and then wouldn't acknowledge that when challenged? On the surface, and for purposes of the point that he made to me as I questioned him, the absolute syncing of clocks is being give too much significance.

You are completely missing the points. In science it is very significant to acknowledge observations and data. It is particularly important if that very data is used to develope a theory. MD is not doing this. He is ignoring that actual measurements and data because it refutes his beliefs.

He is essentially saying - "I chose to reject reality and substitute my own." This is not science and it is not even rational.