Prev: Lunar Laser-Ranging Detection of Light-Speed Anisotropy
Next: Physical Explanation for E=mc^2
From: Bruce Richmond on 25 Feb 2010 20:32
On Feb 24, 1:31 am, "J. Clarke" <jclarke.use...(a)cox.net> wrote:
> On 2/23/2010 11:38 PM, Bruce Richmond wrote:
>
>
>
>
>
> > On Feb 23, 9:50 pm, "J. Clarke"<jclarke.use...(a)cox.net>  wrote:
> >> On 2/23/2010 8:36 PM, Bruce Richmond wrote:
>
> >>> On Feb 21, 11:52 pm, "J. Clarke"<jclarke.use...(a)cox.net>    wrote:
> >>>> On 2/21/2010 10:24 PM, Bruce Richmond wrote:
>
> >>>>> On Feb 21, 6:10 pm, mpalenik<markpale...(a)gmail.com>      wrote:
> >>>>>> On Feb 21, 4:57 pm, Ste<ste_ro...(a)hotmail.com>      wrote:
>
> >>>>>>> If we were to extrapolate a trend from history, then physics has not
> >>>>>>> yet given us a single equation which describes how the universe
> >>>>>>> functions. It has given us some rules of thumb and some cumbersome
> >>>>>>> approximations.
>
> >>>>>> This just further illustrates that you don't understand how physics
> >>>>>> actually works.  The history of physics isn't a series of blunders
> >>>>>> that we've thrown out as we get better and better equations, hampered
> >>>>>> by our belief in the old equations.  Rather, physics at just about
> >>>>>> every point in time since the renaissance has been a journey from very
> >>>>>> specific to more general rules--criteria by which any new physics must
> >>>>>> be constrained.
>
> >>>>>> For example, Kepler, while not really a physicist per-se, devised
> >>>>>> descriptions of the elliptical orbits that planets must follow.
> >>>>>> Newton, then, discovered that this is a special case of the
> >>>>>> conservation of angular momentum, which is a much more general
> >>>>>> principle--however, conservation of angular momentum MUST be able to
> >>>>>> reproduce the elliptical orbits of planets, or else it is wrong.
> >>>>>> Kepler's rules constrained Newton's theories.
>
> >>>>>> Special relativity then changed Newton's laws, a bit.  The basic
> >>>>>> principles, like F = dp/dt remained, but Special relativity says that
> >>>>>> space and time must transform differently than they do in Newtonian
> >>>>>> mechanics.  However, Newtonian mechanics is still a special case of
> >>>>>> special relativity--as the speed of an object approaches zero, the
> >>>>>> laws begin to reproduce Newton's laws.  Newton's laws, in this way,
> >>>>>> constrain Special Relativity.  Because if it did *NOT* reproduce
> >>>>>> Newton's laws at low speeds, it would be wrong.
>
> >>>>>> General relativity came along and it turns out that special relativity
> >>>>>> only works as a limiting case of general relativity, specifically,
> >>>>>> when there is no mass or energy present.  As the amount of mass and
> >>>>>> energy present goes to zero, general relativity reproduces special
> >>>>>> relativity.  If it could not do this, it would be wrong.
>
> >>>>>> Any new physics must be able to reproduce the old physics in the
> >>>>>> regimes in which it has been tested.  Any new theory that cannot do so
> >>>>>> is necessarily wrong because it has already been ruled out by
> >>>>>> experiment.
>
> >>>>> Thank you for bringing this up and explaining it so well.  A few days
> >>>>> ago in the DeSitter thread I wrote that in SR the speed of light is
> >>>>> made a universal constant by the second postulate.  The coordinate
> >>>>> systems are constructed based on that fact.  Because of that there is
> >>>>> no way you can measure the speed of light to be anything but c without
> >>>>> making a mistake.
>
> >>>> What point are you trying to support with that statement?  If one
> >>>> _measures_ a velocity of light other than the one that it is commonly
> >>>> held to have and others replicate your result, and it is found that
> >>>> light has different velocities under different circumstances then it is
> >>>> not the measurement that is a mistake but you will have just thrown
> >>>> relativity right out the window and they'll be seeing you in Stockholm
> >>>> pretty soon.
>
> >>> Hold that prize.  The discussion was about the basis of SR.  I
> >>> consider the second postulate to be a basic concept that SR was
> >>> founded on.  I was informed by some of the experts here that my
> >>> thinking was outdated.
>
> >> You'll find some physicists who put mathematical formalisms over
> >> physical insight--the constancy of the velocity of light was one of
> >> Einstein's two basic postulates and special relativity can be derived
> >> using those postulates.  That it can be derived in other ways doesn't
> >> alter that basic insight.
>
> > The reason I asked Mark's opinion was because of what he wrote just
> > above my "Thank you".  "Any new physics must be able to reproduce the
> > old physics in the regimes in which it has been tested.  Any new
> > theory that cannot do so is necessarily wrong because it has already
> > been ruled out by experiment."
>
> > The experts here have said that the second postulate could be violated
> > without disproving SR.  Considering your statement above about
> > throwing SR out the window I would say you agree with me that they are
> > wrong about that.
>
> > In SR the second postulate reads "light is always propagated in empty
> > space with a definite velocity c which is independent of the state of
> > motion of the emitting body."  That is it travels at some constant
> > speed in such a way that no ray of light could overtake another ray.
> > Remember, I mentioned this exchange took place in the DeSitter
> > thread.  It was DeSitter that argued against the ballistic theory of
> > light, as promoted by Ritz
>
> >http://www.datasync.com/~rsf1/crit/1908a.htm
>
> > In ballistic theory light can travel at c+v which would allow one ray
> > to overtake another.  That would mean there is no single "speed of
> > light".
>
> >> The thing is, either relativity is a usefully accurate description of
> >> reality or it isn't.  If it isn't then someone should be able to conduct
> >> an experiment that is inconsistent with relativity and show that it is
> >> invalid.  So far many experiments have been performed and none have
> >> succeeded in showing it to be invalid.
>
> >>>>> I was then informed that the interpertation of SR
> >>>>> has been improved upon since 1905 and that what I had written no
> >>>>> longer applied.  Further, relativity could survive even if it was
> >>>>> found that the speed of light wasn't exactly c.
>
> >>>> Uh, by definition the velocity of light is exactly c.  Grok the
> >>>> concept--c is defined as "the velocity of light".  Relativity makes no
> >>>> statement concerning a specific value that c must have, only that it is
> >>>> the same in all reference frames.  It can be 2 millimeters per
> >>>> millennium or forty quintillion kilometers per femtosecond and
> >>>> relativity remains valid, as long as it demonstrably has that value and
> >>>> only that value, within the limits of experimental error.
>
> >>> I am well aware that the speed of light is c by definition in SR.
>
> >> No, c is the speed of light, period.  This has nothing to do with
> >> special relativity or general relativity or Newtonian mechanics or
> >> anything else.  The physics community has chosen to write "c" instead of
> >> spelling out "the speed of light, whatever that might be".  You're
> >> reading too much into it.  It's just a shorthand.
>
> > In SR the second postulate reads "light is always propagated in empty
> > space with a definite velocity c which is independent of the state of
> > motion of the emitting body."  That is it travels at some constant
> > speed in such a way that no ray of light could overtake another ray.
> > Remember, I mentioned this exchange took place in the DeSitter
> > thread.  It was DeSitter that argued against the ballistic theory of
> > light, as promoted by Ritz
>
> You're acting like using a letter to refer to a velocity is something
> magic.  It's not, it's just a shorthand.

I was just pointing out that SR declared c a constant as opposed to a
variable.

> >http://www.datasync.com/~rsf1/crit/1908a.htm
>
> > In ballistic theory light can travel at c+v which would allow one ray
> > to overtake another.  That would mean there is no single "speed of
> > light".  So it is a convention of SR, and ether theory, that c is the
> > speed of light.  That is why I included the qualifier "in SR".
>
> The "ballistic theory" is ancient history.

Einstein's 1905 paper is also ancient history according to many around
here. Be that as it may, in the DeSitter thread we were discussing
how it was determined that light travels at "a definite velocity c
which is independent of the state of motion of the emitting body."
Which brought us to how c was determined, and my pointing out that
since the meter is derived from c, you had better measure the speed of
light to be c or you screwed something up. In retrospect I now
realize that I was assuming the second postulate is correct. If
ballistic theory were correct it would be possible for rays to travel
at different speeds.

> >>> That is basicly what I said in the paragraph above that starts with
> >>> "Thank you".  Again the experts told me I was wrong, that the speed of
> >>> light was the distance traveled divided by the time.
>
> >> So what else would be, the color of apples divided by the temperature of
> >> a polar bear's nose?
>
> > If you defined c as the speed of light then the distance is derived
> > from c, not c from the distance.
>
> What distance would that be?
>
> The _distance_ is derived from whatever means you use for measuring
> distance.  It has no bearing on using a letter to refer to the velocity
> of light.
>
> > In effect the distance is ct.
>
> The distance to _what_?

The distance between photo sensors you are using to measure the speed
of light. A meter is defined as the distance travelled by light in
vacuum in 1⁄299,792,458 of a second. So in place of 100 meters
substitute 100⁄299,792,458 light seconds. To eliminate the inaccuracy
of measuring rods use light based measurements to place the sensors.
If you have placed the sensors the correct distance apart so that it
took the calibrating light 100⁄299,792,458 seconds to make the trip,
how long do you think it will take the light you are measuring the
speed of?

>  > If
>
> > you now measure how long it takes light to travel that distance you
> > had better get t or you have proven that the speed of light isn't
> > constant.
>
> No, what you've done is made a measurement.

A circular measurement which you pointed out elsewhere in this tread
is senseless.

> >> c is the velocity of light.  By definition.  That velocity has some
> >> measurable numerical value, you measure the time it takes light to
> >> travel a given distance and you have an approximation of the numerical
> >> value of c.  You measure again with an improved apparatus and you have a
> >> more accurate approximation.  The fact that the two approximations are
> >> different has no bearing on calling the velocity of light "c".
>
> > When I pointed out that in SR the speed of light is c by definition
> > due to the second postulate I was told by the "experts" that I was
> > wrong.
>
> Which experts were these and why do you care so much what they think?
> Read Einstein.
>
> >> Maybe is has more than one value, maybe it has two or three or a
> >> billion--so far though it seems to have just one.
>
> > If it has more than one value then it is not a constant and SR just
> > got flushed down the tubes.
>
> Precisely.  What of it?

As you have seen here, some prefer to just flush the second postulate
and say everything is fine.

- Hide quoted text -
>
> - Show quoted text -

From: Inertial on 25 Feb 2010 20:54

"Bruce Richmond" <bsr3997(a)my-deja.com> wrote in message
news:a068a103-88fa-49a1-8330-990b26c35e5f(a)b30g2000yqd.googlegroups.com...
> On Feb 24, 1:31 am, "J. Clarke" <jclarke.use...(a)cox.net> wrote:

[snip for brevity]

>> You're acting like using a letter to refer to a velocity is something
>> magic. It's not, it's just a shorthand.
>
> I was just pointing out that SR declared c a constant as opposed to a
> variable.

A reasonable proposition, as it always seems to have the same value, as was
further shown in later experiments.


>> >http://www.datasync.com/~rsf1/crit/1908a.htm
>>
>> > In ballistic theory light can travel at c+v which would allow one ray
>> > to overtake another. That would mean there is no single "speed of
>> > light". So it is a convention of SR, and ether theory, that c is the
>> > speed of light. That is why I included the qualifier "in SR".
>>
>> The "ballistic theory" is ancient history.
>
> Einstein's 1905 paper is also ancient history according to many around
> here. Be that as it may, in the DeSitter thread we were discussing
> how it was determined that light travels at "a definite velocity c
> which is independent of the state of motion of the emitting body."

In the 1950 paper it was postulated that it did so .. based at least partly
on measurements of it that showed it to be so in at least some scenarios :)

> Which brought us to how c was determined, and my pointing out that
> since the meter is derived from c,

Not at that time

> you had better measure the speed of
> light to be c or you screwed something up.

Nope .. you can still measure the speed of light, and if you get different
results from different sources, that does not mean you screwed up .. it
means the speed of light is not constant.

> In retrospect I now
> realize that I was assuming the second postulate is correct. If
> ballistic theory were correct it would be possible for rays to travel
> at different speeds.

But we know ballistic theory is NOT correct, so that's rather a moot point.

>> >>> That is basicly what I said in the paragraph above that starts with
>> >>> "Thank you". Again the experts told me I was wrong, that the speed
>> >>> of
>> >>> light was the distance traveled divided by the time.
>>
>> >> So what else would be, the color of apples divided by the temperature
>> >> of
>> >> a polar bear's nose?
>>
>> > If you defined c as the speed of light then the distance is derived
>> > from c, not c from the distance.
>>
>> What distance would that be?
>>
>> The _distance_ is derived from whatever means you use for measuring
>> distance. It has no bearing on using a letter to refer to the velocity
>> of light.
>>
>> > In effect the distance is ct.
>>
>> The distance to _what_?
>
> The distance between photo sensors you are using to measure the speed
> of light. A meter is defined as the distance travelled by light in
> vacuum in 1⁄299,792,458 of a second.

Which light. One can still test with that that light from different sources
has the same speed.

> So in place of 100 meters
> substitute 100⁄299,792,458 light seconds. To eliminate the inaccuracy
> of measuring rods use light based measurements to place the sensors.
> If you have placed the sensors the correct distance apart so that it
> took the calibrating light 100⁄299,792,458 seconds to make the trip,
> how long do you think it will take the light you are measuring the
> speed of?

You would not use the same light for measuring the distance as you do for
calculating the speed. That would be plain stupid and is not what is done.

>
>> > If
>>
>> > you now measure how long it takes light to travel that distance you
>> > had better get t or you have proven that the speed of light isn't
>> > constant.
>>
>> No, what you've done is made a measurement.
>
> A circular measurement which you pointed out elsewhere in this tread
> is senseless.

Only circular if all light travels at the same speed. And then it doesn't
matter if it is.

>> >> c is the velocity of light. By definition. That velocity has some
>> >> measurable numerical value, you measure the time it takes light to
>> >> travel a given distance and you have an approximation of the numerical
>> >> value of c. You measure again with an improved apparatus and you have
>> >> a
>> >> more accurate approximation. The fact that the two approximations are
>> >> different has no bearing on calling the velocity of light "c".
>>
>> > When I pointed out that in SR the speed of light is c by definition
>> > due to the second postulate I was told by the "experts" that I was
>> > wrong.
>>
>> Which experts were these and why do you care so much what they think?
>> Read Einstein.
>>
>> >> Maybe is has more than one value, maybe it has two or three or a
>> >> billion--so far though it seems to have just one.
>>
>> > If it has more than one value then it is not a constant and SR just
>> > got flushed down the tubes.
>>
>> Precisely. What of it?
>
> As you have seen here, some prefer to just flush the second postulate
> and say everything is fine.

If the speed of light is found to be truly source dependent (it hasn't been)
then we'd need to find out how all the experiments that so far have shown it
NOT to be source dependent gave the results that they did.


From: J. Clarke on 25 Feb 2010 21:51
On 2/25/2010 8:32 PM, Bruce Richmond wrote:
> On Feb 24, 1:31 am, "J. Clarke"<jclarke.use...(a)cox.net> wrote:
>> On 2/23/2010 11:38 PM, Bruce Richmond wrote:
>>
>>
>>
>>
>>
>>> On Feb 23, 9:50 pm, "J. Clarke"<jclarke.use...(a)cox.net> wrote:
>>>> On 2/23/2010 8:36 PM, Bruce Richmond wrote:
>>
>>>>> On Feb 21, 11:52 pm, "J. Clarke"<jclarke.use...(a)cox.net> wrote:
>>>>>> On 2/21/2010 10:24 PM, Bruce Richmond wrote:
>>
>>>>>>> On Feb 21, 6:10 pm, mpalenik<markpale...(a)gmail.com> wrote:
>>>>>>>> On Feb 21, 4:57 pm, Ste<ste_ro...(a)hotmail.com> wrote:
>>
>>>>>>>>> If we were to extrapolate a trend from history, then physics has not
>>>>>>>>> yet given us a single equation which describes how the universe
>>>>>>>>> functions. It has given us some rules of thumb and some cumbersome
>>>>>>>>> approximations.
>>
>>>>>>>> This just further illustrates that you don't understand how physics
>>>>>>>> actually works. The history of physics isn't a series of blunders
>>>>>>>> that we've thrown out as we get better and better equations, hampered
>>>>>>>> by our belief in the old equations. Rather, physics at just about
>>>>>>>> every point in time since the renaissance has been a journey from very
>>>>>>>> specific to more general rules--criteria by which any new physics must
>>>>>>>> be constrained.
>>
>>>>>>>> For example, Kepler, while not really a physicist per-se, devised
>>>>>>>> descriptions of the elliptical orbits that planets must follow.
>>>>>>>> Newton, then, discovered that this is a special case of the
>>>>>>>> conservation of angular momentum, which is a much more general
>>>>>>>> principle--however, conservation of angular momentum MUST be able to
>>>>>>>> reproduce the elliptical orbits of planets, or else it is wrong.
>>>>>>>> Kepler's rules constrained Newton's theories.
>>
>>>>>>>> Special relativity then changed Newton's laws, a bit. The basic
>>>>>>>> principles, like F = dp/dt remained, but Special relativity says that
>>>>>>>> space and time must transform differently than they do in Newtonian
>>>>>>>> mechanics. However, Newtonian mechanics is still a special case of
>>>>>>>> special relativity--as the speed of an object approaches zero, the
>>>>>>>> laws begin to reproduce Newton's laws. Newton's laws, in this way,
>>>>>>>> constrain Special Relativity. Because if it did *NOT* reproduce
>>>>>>>> Newton's laws at low speeds, it would be wrong.
>>
>>>>>>>> General relativity came along and it turns out that special relativity
>>>>>>>> only works as a limiting case of general relativity, specifically,
>>>>>>>> when there is no mass or energy present. As the amount of mass and
>>>>>>>> energy present goes to zero, general relativity reproduces special
>>>>>>>> relativity. If it could not do this, it would be wrong.
>>
>>>>>>>> Any new physics must be able to reproduce the old physics in the
>>>>>>>> regimes in which it has been tested. Any new theory that cannot do so
>>>>>>>> is necessarily wrong because it has already been ruled out by
>>>>>>>> experiment.
>>
>>>>>>> Thank you for bringing this up and explaining it so well. A few days
>>>>>>> ago in the DeSitter thread I wrote that in SR the speed of light is
>>>>>>> made a universal constant by the second postulate. The coordinate
>>>>>>> systems are constructed based on that fact. Because of that there is
>>>>>>> no way you can measure the speed of light to be anything but c without
>>>>>>> making a mistake.
>>
>>>>>> What point are you trying to support with that statement? If one
>>>>>> _measures_ a velocity of light other than the one that it is commonly
>>>>>> held to have and others replicate your result, and it is found that
>>>>>> light has different velocities under different circumstances then it is
>>>>>> not the measurement that is a mistake but you will have just thrown
>>>>>> relativity right out the window and they'll be seeing you in Stockholm
>>>>>> pretty soon.
>>
>>>>> Hold that prize. The discussion was about the basis of SR. I
>>>>> consider the second postulate to be a basic concept that SR was
>>>>> founded on. I was informed by some of the experts here that my
>>>>> thinking was outdated.
>>
>>>> You'll find some physicists who put mathematical formalisms over
>>>> physical insight--the constancy of the velocity of light was one of
>>>> Einstein's two basic postulates and special relativity can be derived
>>>> using those postulates. That it can be derived in other ways doesn't
>>>> alter that basic insight.
>>
>>> The reason I asked Mark's opinion was because of what he wrote just
>>> above my "Thank you". "Any new physics must be able to reproduce the
>>> old physics in the regimes in which it has been tested. Any new
>>> theory that cannot do so is necessarily wrong because it has already
>>> been ruled out by experiment."
>>
>>> The experts here have said that the second postulate could be violated
>>> without disproving SR. Considering your statement above about
>>> throwing SR out the window I would say you agree with me that they are
>>> wrong about that.
>>
>>> In SR the second postulate reads "light is always propagated in empty
>>> space with a definite velocity c which is independent of the state of
>>> motion of the emitting body." That is it travels at some constant
>>> speed in such a way that no ray of light could overtake another ray.
>>> Remember, I mentioned this exchange took place in the DeSitter
>>> thread. It was DeSitter that argued against the ballistic theory of
>>> light, as promoted by Ritz
>>
>>> http://www.datasync.com/~rsf1/crit/1908a.htm
>>
>>> In ballistic theory light can travel at c+v which would allow one ray
>>> to overtake another. That would mean there is no single "speed of
>>> light".
>>
>>>> The thing is, either relativity is a usefully accurate description of
>>>> reality or it isn't. If it isn't then someone should be able to conduct
>>>> an experiment that is inconsistent with relativity and show that it is
>>>> invalid. So far many experiments have been performed and none have
>>>> succeeded in showing it to be invalid.
>>
>>>>>>> I was then informed that the interpertation of SR
>>>>>>> has been improved upon since 1905 and that what I had written no
>>>>>>> longer applied. Further, relativity could survive even if it was
>>>>>>> found that the speed of light wasn't exactly c.
>>
>>>>>> Uh, by definition the velocity of light is exactly c. Grok the
>>>>>> concept--c is defined as "the velocity of light". Relativity makes no
>>>>>> statement concerning a specific value that c must have, only that it is
>>>>>> the same in all reference frames. It can be 2 millimeters per
>>>>>> millennium or forty quintillion kilometers per femtosecond and
>>>>>> relativity remains valid, as long as it demonstrably has that value and
>>>>>> only that value, within the limits of experimental error.
>>
>>>>> I am well aware that the speed of light is c by definition in SR.
>>
>>>> No, c is the speed of light, period. This has nothing to do with
>>>> special relativity or general relativity or Newtonian mechanics or
>>>> anything else. The physics community has chosen to write "c" instead of
>>>> spelling out "the speed of light, whatever that might be". You're
>>>> reading too much into it. It's just a shorthand.
>>
>>> In SR the second postulate reads "light is always propagated in empty
>>> space with a definite velocity c which is independent of the state of
>>> motion of the emitting body." That is it travels at some constant
>>> speed in such a way that no ray of light could overtake another ray.
>>> Remember, I mentioned this exchange took place in the DeSitter
>>> thread. It was DeSitter that argued against the ballistic theory of
>>> light, as promoted by Ritz
>>
>> You're acting like using a letter to refer to a velocity is something
>> magic. It's not, it's just a shorthand.
>
> I was just pointing out that SR declared c a constant as opposed to a
> variable.
>
>>> http://www.datasync.com/~rsf1/crit/1908a.htm
>>
>>> In ballistic theory light can travel at c+v which would allow one ray
>>> to overtake another. That would mean there is no single "speed of
>>> light". So it is a convention of SR, and ether theory, that c is the
>>> speed of light. That is why I included the qualifier "in SR".
>>
>> The "ballistic theory" is ancient history.
>
> Einstein's 1905 paper is also ancient history according to many around
> here. Be that as it may, in the DeSitter thread we were discussing
> how it was determined that light travels at "a definite velocity c
> which is independent of the state of motion of the emitting body."
> Which brought us to how c was determined, and my pointing out that
> since the meter is derived from c, you had better measure the speed of
> light to be c or you screwed something up. In retrospect I now
> realize that I was assuming the second postulate is correct. If
> ballistic theory were correct it would be possible for rays to travel
> at different speeds.
>
>>>>> That is basicly what I said in the paragraph above that starts with
>>>>> "Thank you". Again the experts told me I was wrong, that the speed of
>>>>> light was the distance traveled divided by the time.
>>
>>>> So what else would be, the color of apples divided by the temperature of
>>>> a polar bear's nose?
>>
>>> If you defined c as the speed of light then the distance is derived
>>> from c, not c from the distance.
>>
>> What distance would that be?
>>
>> The _distance_ is derived from whatever means you use for measuring
>> distance. It has no bearing on using a letter to refer to the velocity
>> of light.
>>
>>> In effect the distance is ct.
>>
>> The distance to _what_?
>
> The distance between photo sensors you are using to measure the speed
> of light. A meter is defined as the distance travelled by light in
> vacuum in 1⁄299,792,458 of a second. So in place of 100 meters
> substitute 100⁄299,792,458 light seconds. To eliminate the inaccuracy
> of measuring rods use light based measurements to place the sensors.
> If you have placed the sensors the correct distance apart so that it
> took the calibrating light 100⁄299,792,458 seconds to make the trip,
> how long do you think it will take the light you are measuring the
> speed of?

Look, if you don't like the standard definition of a meter take it up
with the standards committee. That definition is quite recent and was
established after a century of research failed to reveal any variation
in the velocity of light.

If you're trying to sell the notion that the velocity of light is
variable in any frame that is accessible to humans, that ship has sailed.

>> > If
>>
>>> you now measure how long it takes light to travel that distance you
>>> had better get t or you have proven that the speed of light isn't
>>> constant.
>>
>> No, what you've done is made a measurement.
>
> A circular measurement which you pointed out elsewhere in this tread
> is senseless.

I have? In what post did I point this out?

>>>> c is the velocity of light. By definition. That velocity has some
>>>> measurable numerical value, you measure the time it takes light to
>>>> travel a given distance and you have an approximation of the numerical
>>>> value of c. You measure again with an improved apparatus and you have a
>>>> more accurate approximation. The fact that the two approximations are
>>>> different has no bearing on calling the velocity of light "c".
>>
>>> When I pointed out that in SR the speed of light is c by definition
>>> due to the second postulate I was told by the "experts" that I was
>>> wrong.
>>
>> Which experts were these and why do you care so much what they think?
>> Read Einstein.
>>
>>>> Maybe is has more than one value, maybe it has two or three or a
>>>> billion--so far though it seems to have just one.
>>
>>> If it has more than one value then it is not a constant and SR just
>>> got flushed down the tubes.
>>
>> Precisely. What of it?
>
> As you have seen here, some prefer to just flush the second postulate
> and say everything is fine.

Who, specifically, give us an example of this "flushing".

From: Ste on 25 Feb 2010 22:05
On 25 Feb, 09:16, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au>
wrote:
> > And on this point, I've repeatedly maintained that it isn't. All
> > you've offered in the converse is a quote by Einstein that it is.
>
> No, I've also referred you to the works of Kuhn and Lakatos. And
> indeed, the very method that you describe involves formulating a
> theory and then testing its predictions - in other words, the tests
> that are carried out are constrained by the predictions made by the
> theory. One would be unlikely to test for something that the theory
> does not predict in the first place.
> ____________________________
> Thus demonstrating you also have no understanding whatsoever of the
> scientific method or these philosophers.

You talk rubbish Peter. Kuhn largely discounted the existence of any
defined "scientific method" consistently followed by scientists.



> The whole point of testing through
> experiment is to look for places where the theory might break down, not
> places where you have tested similar things in the past. The idea is to try
> and disprove the theory, and through failure, demonstrate it is true. This
> is the complete opposite to what you say.

No it isn't. It's the *complete same* as what I said. You yourself say
that (some) scientists are setting out to disprove the existing
accepted theory. And yet the existing theory will in fact be the
theory they are most familiar with as scientists, underpinning their
knowledge and understanding of the natural world, and indeed that
theory will have been responsible for most of the cutting edge
technologies that are available to carry out tests on the natural
world.

Invariably, then, scientists will be mostly oriented towards testing
the *explicit predictions of the existing theory*. And this sort of
testing is undoubtedly *decided by the theory* - you would not test
for predictions that theory didn't make or claim domain over in the
first place.

You are a fool if you can't see that the theory therefore determines
the sorts of tests that are carried out.



> The sad fact that even you must acknowledge - and tell us if you don't - is
> that SR is routinely tested every day of the year in wildly diverse
> environments such as particle accelerators, GPS units, astronomy, and space
> exploration. All completely independent ways of testing, and some giving
> very highg precision indeed.

Not really. The very existence of those technologies is made possible
by SR. One could have a crack at making a machine based on only
classical mechanics, and then marvel at the "ongoing proof of the
theory". Of course, we now know that classical mechanics is only
applicable to reality as an approximation.



> Like it or not, the equations of SR are obviously correct.

Pff. I didn't really say that SR wasn't correct, although I have said
that its conceptual framework doesn't seem very clear. Most conceptual
questions seem to be headed off by claiming that certain observations,
such as the invariance of 'c', are fundamental manifestations of
reality. The same is true when questions are asked about the
wavefunction in QM - questions are headed off by claiming that it is a
fundamental manifestation of reality.



> So the only thing that you can bring to the table is some philosophical
> interpretation of what is "really" going on. This is a task you are poorly
> prepared to do, as you don't understand the current (dominant)
> interpretation of what is really going on, which is Minkowski space-time. It
> is (when you understand it) a very simple model which explains a great deal
> of the physics very simply - in particular the Energy and Momentum of a
> particle. Frankly, you are not going to find a mental model of SR which is
> better or simpler than Minkowski space-time, I very much doubt one exists at
> all.

I also doubt one exists at the moment, but I see that as a problem.
It's utterly irreconcilable, within any conceptual framework that I
know of, to have situations where, for example, a large ladder can end
up in a smaller barn according to an observer stationary in the barn,
but not according to an observer riding the ladder. It's easier to see
why it might be possible for it to *appear* to do so (when the
observers are carefully placed), but it certainly can't happen in
reality.



> Your disbelief of SR stems from the fact that you don't understand it.

My disbelief, really, stems from the blatant lack of conceptual
understanding of the theory. I mean, as I repeatedly point out, I
don't know a single equation of relativity, and yet I can root out the
conceptual contradictions immediately when people here have a crack at
making meaningful qualitative statements in SR. The classic example,
of course, was Paul's contention that "what is simultaneous in one
frame can never be simultaneous in another", which of course isn't
true according to SR. And while I'll excuse it as a slip of his
fingers, I've no doubt that many here understand the qualitative side
of SR so poorly that such a statement did not immediately ring alarm
bells when it was made, and yet indeed they dare to accuse me of "not
understanding".



> That's because you are lazy; you seem intelligent enough to learn it if you
> wanted.

I'm not lazy really, it's just I have little motivation to learn the
mathematical side of SR when I would say it is well beyond my present
mathematical ability, and completely outside of my real interests. My
existing mental models seem adequate to cope with taking the position
of a subjective observer in SR, but I certainly can't reconcile it in
"God mode", and discussions so far don't seem to have suggested that I
will get my answers if only I learned the maths. Indeed, I suspect I'd
get that far and still be raising the same contradictions, at which
point someone would just say "this is what SR is" or "it's a
fundamental manifestation of reality", "you can't describe reality
independent of the observer", etc.



> However, jumping from you don't understand SR to therefore
> physicists are all wrong shows an almighty conceit on your part. Just
> because you are an idiot doesn't mean every physicist in the world is as
> well.

Yawn. You totally fail to grasp the nuance of all the arguments that
I've made so far. If you think that the problem is a lack of
mathematical understanding on my part, then it's almost certainly an
insurmountable allegation, because to disprove it imposes a huge
obligation which will have no payoff for me except the small one of
proving you wrong.



> If you really don't believe that SR has been massively and overwhelmingly
> been "proved" by experimental evidence, just say so, and I will dig up a
> list of experimental proofs for you.

See all of what I've just written in this post.



> If you accept that the equations of SR are correct, then your point in all
> this is ..... ?

My point is that I may as well pat myself on the head with a
housebrick.
From: Ste on 25 Feb 2010 22:08
On 25 Feb, 09:18, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au>
wrote:
> "Ste" <ste_ro...(a)hotmail.com> wrote in message
>
> news:ab0ad038-f849-4d36-a73d-8bbb7bf7e366(a)t23g2000yqt.googlegroups.com...
> On 24 Feb, 17:37, PD <thedraperfam...(a)gmail.com> wrote:
>
>
>
>
>
> > On Feb 24, 2:56 am, Ste <ste_ro...(a)hotmail.com> wrote:
>
> > > Of course, I don't pretend to even have a
> > > speculative account for what this variable may be. I will finish
> > > however by saying that surely you accept that clocks that actually
> > > exist must have some common principles at a fundamental level, and
> > > that if the time dilation phenomenon operates at that level then it's
> > > quite plausible that they would all react in the same way to time
> > > dilation.
>
> > On this last point, I will simply conclude that, yes, indeed all
> > clocks operate with a common principle at some level, and that time
> > dilation operates at that level. That principle and that operation of
> > dilation are PRECISELY what is described by special relativity, as far
> > as we can tell from the evidence we have in hand. Congratulations.
>
> > Now, at this point, I imagine you might say, "But I don't BELIEVE in
> > special relativity and hold faith that there is some OTHER principle
> > and operation of dilation that is responsible for what is going on."
> > That is, of course, a possibility. Anything is possible. However,
> > among those models that have been tested and which do purport to
> > account for the principle that drives dilation, special relativity is
> > the demonstrated winner. You are free to put forward a new candidate
> > to add to the race. There are others who are doing exactly the same
> > thing this very day.
>
> As I say, I don't necessarily disbelieve SR. I just don't think it is
> conceptually very clear.
>
> _____________________________
> Have you tried? Found a simple link or book explaining Minkowski space time
> and tried to go through it? Where do you get stuck?

I think Mark's handful of diagrams and short lessons told me
everything I needed to know about Minkowski spacetime, which is that
however interesting and elegant it may be on a mathematical level, it
would in no way address the real questions that I have.
First  |  Prev  |  Next  |  Last
Pages: 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122
Prev: Lunar Laser-Ranging Detection of Light-Speed Anisotropy
Next: Physical Explanation for E=mc^2