Question on Michelson Morley experiment and length contraction

[ghwellsjr]

I can see that the repetitive process can be used as a unit of comparison, but can't see how it is a unit of the property called time.

If there is a property called time and if it affected all repetitive processes equally, do you agree that any of these repetitive processes could be used as the basis for a valid instrument to measure time?

 

[mangaroosh]

If there is a property called time and if it affected all repetitive processes equally, do you agree that any of these repetitive processes could be used as the basis for a valid instrument to measure time?

that's assuming the conclusion though. how do we know that there actually is a property called time which affects all repetitive processes equally?

 

[harrylin]

[..] I can see that the repetitive process can be used as a unit of comparison, but can't see how it is a unit of the property called time.
[..]
that's assuming the conclusion though. how do we know that there actually is a property called time which affects all repetitive processes equally?

You may think that we have it the wrong way round, but it's easy to show that it's not so. Just consider how the concept of time must have arisen: from the daily sequence of sunrise and sundown, as well as the seasons. Thus, man's concept of "time" was formed by the observation of natural clocks. Man-made clocks came much later, and expensive ones often incorporated models of the sun and moon.

Anyway, for physics we cannot do otherwise than work with measurable standards for all such things as "time" and "temperature" that we may want to describe and predict.

 

[ghwellsjr]

that's assuming the conclusion though. how do we know that there actually is a property called time which affects all repetitive processes equally?

Should we suspend all scientific endeavors until we find a counter example, at which point, we would just be locked into a different conundrum?

 

[mangaroosh]

You may think that we have it the wrong way round, but it's easy to show that it's not so. Just consider how the concept of time must have arisen: from the daily sequence of sunrise and sundown, as well as the seasons. Thus, man's concept of "time" was formed by the observation of natural clocks. Man-made clocks came much later, and expensive ones often incorporated models of the sun and moon.

Anyway, for physics we cannot do otherwise than work with measurable standards for all such things as "time" and "temperature" that we may want to describe and predict.

the same problem applies to those natural clocks; how do they measure the property called time?

 

[mangaroosh]

Should we suspend all scientific endeavors until we find a counter example, at which point, we would just be locked into a different conundrum?

not at all; all that should happen is that science should do what science does best*, challenge our assumptions about the nature of the universe; otherwise any theory which includes time as a property and measures that property using a clock is arguably guilty of circular reasoning.

*forgive the personification of science

 

[harrylin]

the same problem applies to those natural clocks; how do they measure the property called time?

Again, it's the inverse: the concept "time" arose from observing the natural cycles. Naturally people decided to divide the year in (moon-) months and (solar) days. That's how people started to use the natural clocks that they observed, as measurement instruments for the progress of natural processes (such as aging, growing to harvest, etc); and this concept that evolved with the use of those clocks they called "time".

 

[mangaroosh]

Again, it's the inverse: the concept "time" arose from observing the natural cycles. Naturally people decided to divide the year in (moon-) months and (solar) days. That's how people started to use the natural clocks that they observed, as measurement instruments for the progress of natural processes (such as aging, growing to harvest, etc); and this concept that evolved with the use of those clocks they called "time".

I would agree that the concept of time arose from observing such natural cycles, coupled with man's innate capacity for memory; but that is all time is, a concept.

EDIT: regardless of how the concept arose though, it doesn't support the contention that time is a property of the universe which can be measured; or that any kind of clock, natural or manmade, actually measures a property called time.

 

[mangaroosh]

It might also be worth pointing out that the concept of a geocentric universe also arose from observing such natural cycles, until the assumption was challenged.

 

[ghwellsjr]

Should we suspend all scientific endeavors until we find a counter example, at which point, we would just be locked into a different conundrum?

not at all; all that should happen is that science should do what science does best*, challenge our assumptions about the nature of the universe; otherwise any theory which includes time as a property and measures that property using a clock is arguably guilty of circular reasoning.

*forgive the personification of science

Even if this were true or even if it were false but you believed it to be true, it won't hamper you from learning relativity which is what this forum is for. I'm only interested in helping those people who want to learn about Special Relativity. Are you one of those people?

 

[mangaroosh]

Even if this were true or even if it were false but you believed it to be true, it won't hamper you from learning relativity which is what this forum is for. I'm only interested in helping those people who want to learn about Special Relativity. Are you one of those people?

I am interested in learning about Special Relativity, and I appreciate your taking the time to go through it with me. For me though learning doesn't simply mean accepting what is said, it involves questioing it and challenging it so that it is understood; that includes challenging the assumptions of it.

As for the truth of the notion that time is a system of measurment and not a property, that is easily verified with some honest questioning.

 

[harrylin]

I would agree that the concept of time arose from observing such natural cycles, coupled with man's innate capacity for memory; but that is all time is, a concept.

EDIT: regardless of how the concept arose though, it doesn't support the contention that time is a property of the universe which can be measured; or that any kind of clock, natural or manmade, actually measures a property called time.

Everything that we measure relates to human concepts about nature. This is really philosophy, and although interesting, it's a bit off-topic here. You may be interested to read a philosophically oriented paper about special relativity, as you will probably appreciate the introduction:

The evolution of space and time, Langevin.
http://en.wikisource.org/wiki/The_Evolution_of_Space_and_Time

 

[mangaroosh]

Everything that we measure relates to human concepts about nature. This is really philosophy, and although interesting, it's a bit off-topic here. You may be interested to read a philosophically oriented paper about special relativity, as you will probably appreciate the introduction:

The evolution of space and time, Langevin.
http://en.wikisource.org/wiki/The_Evolution_of_Space_and_Time

cheers, I'll give that a look.

It is essentially a philosophical consideration, because it is a philosophical assumption [apparently] inherent in the model. The difference between measurnig time and other concepts about nature is that other concepts about nature actually correspond to real things, which can be measured, time doesn't appear to be; that is, it is assumed to be, but when considered, it doesn't appear to be.

 

[logics]

I'm only interested in helping those people who want to learn about Special Relativity. Are you one of those people?

I am, ghwellsjr. hi, , and I hope you'll be patient with me, too!

If I may: "time" is a concept, an abstract idea (a *category) we need to describe only a dynamic world (being, entity, existing), if world were static, we would not need it (if absolute time would exist all the same, is a philosophical speculation, but we surely couldn't measure/perceive it)
so, we describe dynamic(ity), dynamism, or (choosing a common word) "change", we can measure change with every thing, phenomenon; it must not be repetitive, only regular, in order to be reliable. Motion, of course, is the obvious, patent phenomenon representing change[(of place], but we can use any invisible, internal phisical process as a "standard".
We measured "time-change" counting oscillation of a pendulum (gravity), measuring space, length, distance traveled by Sun etc, but also measuring mass, volume (water, sand) etc, now we measure "transitions ...of caesium", to-morrow who knows?
This is fundamental if we want to understand relativity: one standard of measurement doesn't and can't influence another standard. We do not measure time, not even change bu: space, mass etc.

(* "property, quality, attribute" has same ontological status as "time": category of being)

[If you allow me, I want to draw your attention to a problem similar to MM but in which length contraction doesn't help:
Imagine a platform and a train speeding N(orth) at 50 m/s. On both, a man pushes a ball (mass= x Kg) N. One ball moves at 51 the other at 1 m/s, N. The two men do same work? one ball gets 2500 times KE?]
EDIT: I know it doesn't regard SR and length contraction, I am presenting it just as a possibly interesting analogy with MM. I do not expect a reply

 

[harrylin]

[..]
If you allow me, I want to draw your attention to a problem similar to MM but in which length contraction doesn't help:
Imagine a platform and a train speeding N(orth) at 50 m/s. On both, a man pushes a ball (mass= x Kg) N. One ball moves at 51 the other at 1 m/s, N. The two men do same work? one ball gets 2500 times KE?
[..]

That doesn't fit in this topic, and it isn't specifically a problem of SR but the same in classical physics. Coincidentally it is a fresh topic there, so please comment in that thread:

https://www.physicsforums.com/showthread.php?t=534883

If next you have a question how the same works in SR (roughly the same), then please begin a topic on that here.

 

[logics]

That doesn't fit in this topic..If next you have a question.

my note is not a question, just a "frame-of-reference analogy" hint, regarding [topic]MM experiment, my post, regards time.