| Topic: |
Science > Physics |
| User: |
"" |
| Date: |
11 Aug 2005 11:01:07 PM |
| Object: |
basic question classical v. relativity |
I took high school physics over the summer, and at the end we touched
on relativity, just a bit. This is probably overly simplistic, but
relativity seems to claim (among other things I'm sure) that you can't
just describe the motion of an object and leave it at that -- you have
to include the frame of reference that you took your measurement from,
because the motion of the object will measure differently depending on
your frame of reference. My question is, this seems like such an
obvious fact --I find it hard to believe that Newton (or at least one
of his followers) didn't realize this. And if Newton did know this,
which frame of reference did he identify as the "true" one, and why?
Thanks,
C
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| User: "Herman Trivilino" |
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| Title: Re: basic question classical v. relativity |
12 Aug 2005 06:02:29 AM |
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<zxcv_890@hotmail.com> wrote ...
relativity seems to claim (among other things I'm sure) that you can't
just describe the motion of an object and leave it at that -- you have
to include the frame of reference that you took your measurement from,
because the motion of the object will measure differently depending on
your frame of reference.
Yes. That's true. But there's more to it than what you've satated. The
reason one needs to do what you've described is becasue all inertial
reference frames are equivalent. And it is one of the most profound facts
about the universe we live in. It's even got a name. The Principle of
Relativity. (It is also known as the First Postulate).
My question is, this seems like such an
obvious fact --I find it hard to believe that Newton (or at least one
of his followers) didn't realize this.
Newton did realize this. It had been stated a generation earlier by
Galileo. It's the basis of what's called Galilean Relativity. What you
studied is often called Einsteinian Relativity.
Newton's First Law is actually an assertion that all inertial reference
frames are equivalent.
And if Newton did know this,
which frame of reference did he identify as the "true" one, and why?
I'm not sure. I do know, though, that later generations of physicists
(actually, they were called natural philosophers back then) referred to a
frame of reference they called the "fixed stars". It wasn't until a series
of experiements were done in the late 1800's and early 1900's (the most
famous being the Michaelson-Morley experiment of 1889 conducted at the Case
Western Reserve in Ohio) that the notion of a Newtonian "true" rest frame
was abandoned.
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| User: "" |
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| Title: Re: basic question classical v. relativity |
12 Aug 2005 11:07:50 AM |
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Herman Trivilino wrote:
<zxcv_890@hotmail.com> wrote ...
relativity seems to claim (among other things I'm sure) that you can't
just describe the motion of an object and leave it at that -- you have
to include the frame of reference that you took your measurement from,
because the motion of the object will measure differently depending on
your frame of reference.
Yes. That's true. But there's more to it than what you've satated. The
reason one needs to do what you've described is becasue all inertial
reference frames are equivalent. And it is one of the most profound facts
about the universe we live in. It's even got a name. The Principle of
Relativity. (It is also known as the First Postulate).
My question is, this seems like such an
obvious fact --I find it hard to believe that Newton (or at least one
of his followers) didn't realize this.
Newton did realize this. It had been stated a generation earlier by
Galileo. It's the basis of what's called Galilean Relativity. What you
studied is often called Einsteinian Relativity.
So you're saying that Einstein's first postulate "The Principle of
Relativity" was not originated by him, but by Galileo? That's funny,
because my teacher made it sound like Einstein invented that.
Newton's First Law is actually an assertion that all inertial reference
frames are equivalent.
I don't see the connection. The first law states that an object is at
rest or travels at constant velocity unless a net force is acting on
it, in which case it will be accelerating. How is that related to
inertial reference frames being equivalent?
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| User: "PD" |
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| Title: Re: basic question classical v. relativity |
12 Aug 2005 12:23:32 PM |
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wrote:
Herman Trivilino wrote:
< > wrote ...
relativity seems to claim (among other things I'm sure) that you can't
just describe the motion of an object and leave it at that -- you have
to include the frame of reference that you took your measurement from,
because the motion of the object will measure differently depending on
your frame of reference.
Yes. That's true. But there's more to it than what you've satated. The
reason one needs to do what you've described is becasue all inertial
reference frames are equivalent. And it is one of the most profound facts
about the universe we live in. It's even got a name. The Principle of
Relativity. (It is also known as the First Postulate).
My question is, this seems like such an
obvious fact --I find it hard to believe that Newton (or at least one
of his followers) didn't realize this.
Newton did realize this. It had been stated a generation earlier by
Galileo. It's the basis of what's called Galilean Relativity. What you
studied is often called Einsteinian Relativity.
So you're saying that Einstein's first postulate "The Principle of
Relativity" was not originated by him, but by Galileo? That's funny,
because my teacher made it sound like Einstein invented that.
Perhaps your teacher has also not been instilled with a deeper insight.
:)
There were two suppositions by Einstein. One was nothing more than what
Galileo said: all laws of physics are the same in all inertial
reference frames. The other was, by the way, that applies to
electrodynamics, too. Naturally, Galileo had no basis for realizing
that all hell would break loose in so doing. Einstein was the one who
chased that little rabbit down a dark, dark hole.
Newton's First Law is actually an assertion that all inertial reference
frames are equivalent.
I don't see the connection. The first law states that an object is at
rest or travels at constant velocity unless a net force is acting on
it, in which case it will be accelerating. How is that related to
inertial reference frames being equivalent?
"At rest OR travels at constant velocity". The OR is the nub. That is,
there is no difference in the physics between something at rest or
something moving at constant velocity. When something physical happens
(a force), then this produces a *change* in velocity, but it is not
responsible for velocity itself. You know this from common experience.
You can fall asleep on a plane, even though it is traveling at 500 mph,
and if you drop your iPod, it will still land at your feet. (Note that
as soon as the pilot *decelerates*, you wake up.) Even sitting here
reading this, you are completely oblivious to screaming along at
something like 1000 mph as the continent moves from west to east. It
makes no difference whether you treat the system as though it were
going 1000 mph or standing still; the physics is identical.
PD
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| User: "Andy Resnick" |
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| Title: Re: basic question classical v. relativity |
12 Aug 2005 08:57:40 AM |
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wrote:
<snip>
And if Newton did know this,
which frame of reference did he identify as the "true" one, and why?
Newton identified the "fixed stars in heaven" as a frame of reference.
Because at the time, it was assumed the universe was a static entity.
This was invoked to understand the dynamics of water (actually, just the
shape of the surface) in a rotating pail.
--
Andrew Resnick, Ph.D.
Department of Physiology and Biophysics
Case Western Reserve University
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| User: "" |
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| Title: Re: basic question classical v. relativity |
12 Aug 2005 02:33:38 PM |
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In article <ddia0a$j52$2@eeyore.INS.cwru.edu>, Andy Resnick <andy.resnick@op.case.edu> writes:
zxcv_890@hotmail.com wrote:
<snip>
And if Newton did know this,
which frame of reference did he identify as the "true" one, and why?
Newton identified the "fixed stars in heaven" as a frame of reference.
Because at the time, it was assumed the universe was a static entity.
This was invoked to understand the dynamics of water (actually, just the
shape of the surface) in a rotating pail.
However, since any frame of reference moving at constent velocity to
the one above is equivalent to it, there is no single "true" frame of
reference, rather an infinite family of such.
Mati Meron | "When you argue with a fool,
meron@cars.uchicago.edu | chances are he is doing just the same"
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| User: "Uncle Al" |
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| Title: Re: basic question classical v. relativity |
12 Aug 2005 11:25:16 AM |
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wrote:
I took high school physics over the summer, and at the end we touched
on relativity, just a bit. This is probably overly simplistic, but
relativity seems to claim (among other things I'm sure) that you can't
just describe the motion of an object and leave it at that -- you have
to include the frame of reference that you took your measurement from,
because the motion of the object will measure differently depending on
your frame of reference. My question is, this seems like such an
obvious fact --I find it hard to believe that Newton (or at least one
of his followers) didn't realize this. And if Newton did know this,
which frame of reference did he identify as the "true" one, and why?
Newtonian physics tacitly assumes lightspeed is infinite. Information
is then instantly available - the entire system is characterized
without delay. But lightspeed is finite and pbservation of
information is delayed with distance, hence Special Relativity,
http://bkocay.cs.umanitoba.ca/Students/Theory.html
--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/qz.pdf
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| User: "" |
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| Title: Re: basic question classical v. relativity |
12 Aug 2005 02:59:01 PM |
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In article <42FCCD6C.6A8488BD@hate.spam.net>, Uncle Al <UncleAl0@hate.spam.net> writes:
zxcv_890@hotmail.com wrote:
I took high school physics over the summer, and at the end we touched
on relativity, just a bit. This is probably overly simplistic, but
relativity seems to claim (among other things I'm sure) that you can't
just describe the motion of an object and leave it at that -- you have
to include the frame of reference that you took your measurement from,
because the motion of the object will measure differently depending on
your frame of reference. My question is, this seems like such an
obvious fact --I find it hard to believe that Newton (or at least one
of his followers) didn't realize this. And if Newton did know this,
which frame of reference did he identify as the "true" one, and why?
Newtonian physics tacitly assumes lightspeed is infinite.
No, Newtonian physics ***doesn't***, tacitly or otherwise assume
***anything*** about lightspeed. It plays no role in it.
You're propagating a common fallacy here. It is a common situation
(standard one, in fact) that an existing theory T is getting embedded
in a new theory NT, such that the old theory is recoverable from the
old one as limiting case. Schematically you can think about NT as
depending upon some parameter (or set of parameters) p so that
(p -> 0) ==> (NT(p) - T)
You can use infinity instead of 0, if you wish. the point is, the
above does not mean, that T assumes (tacitly or otherwise) that p = 0.
It simply assumes nothing about p (may not even recognize it).
For example, Euclidean geometry can be obtained from a Riemannian one
at the limit of zero curvature. This doesn't mean, however, that
Euclid assumed zero curvature of space. He assumed nothing about
curvature of space, it is not a factor in his geometry.
Furthermore ...
Information
is then instantly available - the entire system is characterized
without delay. But lightspeed is finite and pbservation of
information is delayed with distance, hence Special Relativity,
.... there is confusion here, as well. The finite speed of propagation
of information, c, is a key point, indeed. This however, apriori, has
nothing to do with light speed. Remember, it is not that c is
lightspeed, rather that lightspeed happens to be c.
Mati Meron | "When you argue with a fool,
meron@cars.uchicago.edu | chances are he is doing just the same"
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| User: "Mike" |
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| Title: Re: basic question classical v. relativity |
13 Aug 2005 10:27:46 AM |
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Uncle Al wrote:
zxcv_890@hotmail.com wrote:
I took high school physics over the summer, and at the end we touched
on relativity, just a bit. This is probably overly simplistic, but
relativity seems to claim (among other things I'm sure) that you can't
just describe the motion of an object and leave it at that -- you have
to include the frame of reference that you took your measurement from,
because the motion of the object will measure differently depending on
your frame of reference. My question is, this seems like such an
obvious fact --I find it hard to believe that Newton (or at least one
of his followers) didn't realize this. And if Newton did know this,
which frame of reference did he identify as the "true" one, and why?
Newtonian physics tacitly assumes lightspeed is infinite. Information
is then instantly available - the entire system is characterized
without delay. But lightspeed is finite and pbservation of
information is delayed with distance, hence Special Relativity,
http://bkocay.cs.umanitoba.ca/Students/Theory.html
No, that's a cheap argument so that SR is presented as a new theory.
What Newtonian physics assumes is action_at_a_distance, and thus an
infinite speed of gravity.
Newton framed no hypothesis as to why speed of gravity is infinite, and
apparently is, in a 3-D world, relativized or not. On the contrary,
Einstein framed a hypothesis that the OWSL is c, something that cannot
be proven in the framework of SR and thus, in a 4-D spacetime, speed of
gravity is assumed to be equal to c. But only assumed so...
But of course, 4-D spacetime is something unobservable as much as the
absolute space and time of Newton are.
Mike
--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/qz.pdf
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| User: "Sam Wormley" |
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| Title: Re: basic question classical v. relativity |
11 Aug 2005 11:08:58 PM |
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wrote:
I took high school physics over the summer, and at the end we touched
on relativity, just a bit. This is probably overly simplistic, but
relativity seems to claim (among other things I'm sure) that you can't
just describe the motion of an object and leave it at that -- you have
to include the frame of reference that you took your measurement from,
because the motion of the object will measure differently depending on
your frame of reference. My question is, this seems like such an
obvious fact --I find it hard to believe that Newton (or at least one
of his followers) didn't realize this. And if Newton did know this,
which frame of reference did he identify as the "true" one, and why?
Thanks,
C
This wasn't an issue in Newton's time--relativistic effects
were not observed. Galilean relativity, especially as codified,
in Newton's laws of motion, accounted for all that was observed.
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| User: "Bruce Scott TOK" |
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| Title: Re: basic question classical v. relativity |
12 Aug 2005 06:09:51 AM |
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Sam W wrote:
zxcv_890@hotmail.com wrote:
I took high school physics over the summer, and at the end we touched
on relativity, just a bit. This is probably overly simplistic, but
relativity seems to claim (among other things I'm sure) that you can't
just describe the motion of an object and leave it at that -- you have
to include the frame of reference that you took your measurement from,
because the motion of the object will measure differently depending on
your frame of reference. My question is, this seems like such an
obvious fact --I find it hard to believe that Newton (or at least one
of his followers) didn't realize this. And if Newton did know this,
which frame of reference did he identify as the "true" one, and why?
This wasn't an issue in Newton's time--relativistic effects
were not observed. Galilean relativity, especially as codified,
in Newton's laws of motion, accounted for all that was observed.
Just to add to this... special relativity didn't become an issue until
electromagnetism cane along... propagation of light and interactions
with rigid bodies were what got Einstein and his colleagues going.
--
ciao,
Bruce
drift wave turbulence: http://www.rzg.mpg.de/~bds/
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| User: "" |
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| Title: Re: basic question classical v. relativity |
12 Aug 2005 01:53:31 AM |
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In article <1123817995.903921.123060@g43g2000cwa.googlegroups.com>, writes:
I took high school physics over the summer, and at the end we touched
on relativity, just a bit. This is probably overly simplistic, but
relativity seems to claim (among other things I'm sure) that you can't
just describe the motion of an object and leave it at that -- you have
to include the frame of reference that you took your measurement from,
because the motion of the object will measure differently depending on
your frame of reference.
Of course, same is true about Newtonian mechanics.
My question is, this seems like such an
obvious fact --I find it hard to believe that Newton (or at least one
of his followers) didn't realize this.
Of course he did. The first of the three laws defines an inertial
reference frame.
And if Newton did know this,
which frame of reference did he identify as the "true" one, and why?
None. See above. Both Newtonian and Einsteinian mechanics are
relativistic, the difference is in the rules governing transformations
between reference frames.
Mati Meron | "When you argue with a fool,
meron@cars.uchicago.edu | chances are he is doing just the same"
.
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| User: "Mike" |
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| Title: Re: basic question classical v. relativity |
13 Aug 2005 10:06:55 AM |
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wrote:
In article <1123817995.903921.123060@g43g2000cwa.googlegroups.com>, writes:
I took high school physics over the summer, and at the end we touched
on relativity, just a bit. This is probably overly simplistic, but
relativity seems to claim (among other things I'm sure) that you can't
just describe the motion of an object and leave it at that -- you have
to include the frame of reference that you took your measurement from,
because the motion of the object will measure differently depending on
your frame of reference.
Of course, same is true about Newtonian mechanics.
My question is, this seems like such an
obvious fact --I find it hard to believe that Newton (or at least one
of his followers) didn't realize this.
Of course he did. The first of the three laws defines an inertial
reference frame.
And if Newton did know this,
which frame of reference did he identify as the "true" one, and why?
None. See above. Both Newtonian and Einsteinian mechanics are
relativistic, the difference is in the rules governing transformations
between reference frames.
Wrong. Newton used several eexperiments, such as the rotating bucket in
order to assert that there is an absolute space, what is called in
modern terminology substantival space. There is an axtensive argument
in the literature between leibniz and Newton's authorized
representative, Clark, arguing about this.
Thus, Newtonian mechanics are not relativistic but neither is
Einstein's SR. The name of the latter is a misnomer, as was indicated
by Max Planck who called SR the theory of absolutes (and Einstein
agreed but said it was to late to change the name... hahahahahah). It
turns out that the spacetime of SR is also substantival (it means that
the spacetime exists independently of the events taking place in it)
which is exactly what Newton's is. Note that there is plenty of
controversy whether GR spacetime is substantival but most belive it is
since deviations from geodesics must be referenced absolutely (failure
to incorporate Mach's philosophy).
But yes, the transformations are different just because Newtonian
mechanics assumes action_at_a_distance, whereas in SR and GR action
propagation in causal relations is limited by the speed of light c.
Now, since action_at_a_distance is already proven over and over again
in QM experiments, SR and GR have been falsified in a grand way and
what is left is finding a way to merge Newtonian macrocosm physics with
QM microcosm physics.
Mike
Mati Meron | "When you argue with a fool,
meron@cars.uchicago.edu | chances are he is doing just the same"
.
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| User: "" |
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| Title: Re: basic question classical v. relativity |
12 Aug 2005 02:30:24 AM |
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In article <LHXKe.36$45.4610@news.uchicago.edu>,
wrote:
In article <1123817995.903921.123060@g43g2000cwa.googlegroups.com>,
zxcv_890@hotmail.com writes:
I took high school physics over the summer, and at the end we touched
on relativity, just a bit. This is probably overly simplistic, but
relativity seems to claim (among other things I'm sure) that you can't
just describe the motion of an object and leave it at that -- you have
to include the frame of reference that you took your measurement from,
because the motion of the object will measure differently depending on
your frame of reference.
Of course, same is true about Newtonian mechanics.
My question is, this seems like such an
obvious fact --I find it hard to believe that Newton (or at least one
of his followers) didn't realize this.
Of course he did. The first of the three laws defines an inertial
reference frame.
And if Newton did know this,
which frame of reference did he identify as the "true" one, and why?
None. See above. Both Newtonian and Einsteinian mechanics are
relativistic, the difference is in the rules governing transformations
between reference frames.
I don't remember this being explicitly pointed out in any
of my physics classes. My recall has disintegrated quite
a bit, though.
/BAH
Subtract a hundred and four for e-mail.
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| User: "Herman Trivilino" |
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| Title: Re: basic question classical v. relativity |
12 Aug 2005 06:06:05 AM |
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<jmfbahciv@aol.com> wrote ...
None. See above. Both Newtonian and Einsteinian mechanics are
relativistic, the difference is in the rules governing transformations
between reference frames.
I don't remember this being explicitly pointed out in any
of my physics classes. My recall has disintegrated quite
a bit, though.
Does this ring a bell? Newtons laws are valid only in inertial reference
frames. And when one works in noninertial reference frames one can invent
pseudoforces so that Newton's Laws can be applied as if one were in in an
inertial reference frame?
+
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| User: "" |
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| Title: Re: basic question classical v. relativity |
12 Aug 2005 04:00:49 AM |
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In article <1123844912_10855@spool6-east.superfeed.net>,
"Herman Trivilino" <physhead@kingwoodREMOVECAPScable.com> wrote:
<jmfbahciv@aol.com> wrote ...
None. See above. Both Newtonian and Einsteinian mechanics are
relativistic, the difference is in the rules governing transformations
between reference frames.
I don't remember this being explicitly pointed out in any
of my physics classes. My recall has disintegrated quite
a bit, though.
Does this ring a bell? Newtons laws are valid only in inertial reference
frames. And when one works in noninertial reference frames one can invent
pseudoforces so that Newton's Laws can be applied as if one were in in an
inertial reference frame?
Yup. But frames weren't defined. They were just words
associated with [emoticon waves hand]something or other.
There wasn't a geometric comparision. I need a map to
get from here to there. IIRC, I was simply handed that
formula and essentially told use this instead of that one.
I can do that; it's similar to using a y rather than an
x in high school algebra. (Remember this kindergarten
stages of physics.) So how do I do a problem. I first
figure out which formula to use, then I do the plugging.
This is NOT the way physics is done in the Real World.
I don't remember doing a transformation in Newtonian
physics. I may have done the action but I would not
be able to point at my piece of paper and say, "That's
the Newtonian transformation."
I'm describing this badly.
/BAH
Subtract a hundred and four for e-mail.
.
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| User: "Herman Trivilino" |
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| Title: Re: basic question classical v. relativity |
13 Aug 2005 02:54:55 PM |
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<jmfbahciv@aol.com> wrote ...
(Remember this kindergarten
stages of physics.) So how do I do a problem. I first
figure out which formula to use, then I do the plugging.
This is NOT the way physics is done in the Real World.
And it's NOT the way physics is always taught.
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| User: "" |
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| Title: Re: basic question classical v. relativity |
12 Aug 2005 02:27:55 PM |
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In article <1123844912_10855@spool6-east.superfeed.net>, "Herman Trivilino" <physhead@kingwoodREMOVECAPScable.com> writes:
<jmfbahciv@aol.com> wrote ...
None. See above. Both Newtonian and Einsteinian mechanics are
relativistic, the difference is in the rules governing transformations
between reference frames.
I don't remember this being explicitly pointed out in any
of my physics classes. My recall has disintegrated quite
a bit, though.
Does this ring a bell? Newtons laws are valid only in inertial reference
frames. And when one works in noninertial reference frames one can invent
pseudoforces so that Newton's Laws can be applied as if one were in in an
inertial reference frame?
+
And one of the characteristics of pseudoforces is that they act on all
masses same way, meaning the resulting acceleration in a given place
and time is independent of the mass the force acts on.
Mati Meron | "When you argue with a fool,
meron@cars.uchicago.edu | chances are he is doing just the same"
.
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| User: "Edward Green" |
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| Title: Re: basic question classical v. relativity |
13 Aug 2005 09:37:02 AM |
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wrote:
In article <1123844912_10855@spool6-east.superfeed.net>, "Herman Trivilino" <physhead@kingwoodREMOVECAPScable.com> writes:
<jmfbahciv@aol.com> wrote ...
None. See above. Both Newtonian and Einsteinian mechanics are
relativistic, the difference is in the rules governing transformations
between reference frames.
So each time we handle Newtonian mechanics we are really doing
"relativistic physics"? Hmm... :-)
I don't remember this being explicitly pointed out in any
of my physics classes. My recall has disintegrated quite
a bit, though.
Does this ring a bell? Newtons laws are valid only in inertial reference
frames. And when one works in noninertial reference frames one can invent
pseudoforces so that Newton's Laws can be applied as if one were in in an
inertial reference frame?
+
And one of the characteristics of pseudoforces is that they act on all
masses same way, meaning the resulting acceleration in a given place
and time is independent of the mass the force acts on.
It's sometime not clear where the pseudoforce lies. From a Newtonian
point of view gravity is a force, and as seen in a rotating frame a
pseudoforce is opposing gravity to keep an object in orbit. But from a
more modern point of view a body in orbit is subjected to no force at
all, whereas for an object on the ground seen in a reference frame
attached to the ground we introduce a pseudoforce (gravity) to explain
why the constant contact force does not result in constant
acceleration.
.
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| User: "Mike" |
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| Title: Re: basic question classical v. relativity |
13 Aug 2005 10:16:32 AM |
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Edward Green wrote:
It's sometime not clear where the pseudoforce lies. From a Newtonian
point of view gravity is a force, and as seen in a rotating frame a
pseudoforce is opposing gravity to keep an object in orbit. But from a
more modern point of view a body in orbit is subjected to no force at
all, whereas for an object on the ground seen in a reference frame
attached to the ground we introduce a pseudoforce (gravity) to explain
why the constant contact force does not result in constant
acceleration.
Newton was extremely clear about pseudoforces, like coriolis and
centrifugal. They arise, according to Newton, because of the
application of the LAWS OF NATURE in the WRONG REFERENCE FRAME. The
correct reference frame, according to Newton, is absolute space, which
can be approximated in practice by the fixed stars.
But from a
more modern point of view a body in orbit is subjected to no force at
all, whereas for an object on the ground seen in a reference frame
attached to the ground we introduce a pseudoforce (gravity) to explain
why the constant contact force does not result in constant
acceleration.
Newton's argument is very strong and Einstein did nothing to rebut it
other than using a math trick to derive the Lorentz transformations.
Mike
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| User: "" |
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| Title: Re: basic question classical v. relativity |
14 Aug 2005 01:48:46 AM |
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In article <1123943822.109344.121330@g14g2000cwa.googlegroups.com>, "Edward Green" <spamspamspam3@netzero.com> writes:
mmeron@cars3.uchicago.edu wrote:
In article <1123844912_10855@spool6-east.superfeed.net>, "Herman Trivilino" <physhead@kingwoodREMOVECAPScable.com> writes:
<jmfbahciv@aol.com> wrote ...
None. See above. Both Newtonian and Einsteinian mechanics are
relativistic, the difference is in the rules governing transformations
between reference frames.
So each time we handle Newtonian mechanics we are really doing
"relativistic physics"? Hmm... :-)
Galilean relativistic, yes.
I don't remember this being explicitly pointed out in any
of my physics classes. My recall has disintegrated quite
a bit, though.
Does this ring a bell? Newtons laws are valid only in inertial reference
frames. And when one works in noninertial reference frames one can invent
pseudoforces so that Newton's Laws can be applied as if one were in in an
inertial reference frame?
+
And one of the characteristics of pseudoforces is that they act on all
masses same way, meaning the resulting acceleration in a given place
and time is independent of the mass the force acts on.
It's sometime not clear where the pseudoforce lies. From a Newtonian
point of view gravity is a force, and as seen in a rotating frame a
pseudoforce is opposing gravity to keep an object in orbit. But from a
more modern point of view a body in orbit is subjected to no force at
all, whereas for an object on the ground seen in a reference frame
attached to the ground we introduce a pseudoforce (gravity) to explain
why the constant contact force does not result in constant
acceleration.
Well, The freedom of flexible geometry allows you to change your view
point. And would that have been all there is to is, moving over to
the column labeled "geometry" what was before in the "dynamics"
column, with no difference in measurable outcomes, then this really
would've been no more than a different point of view. But, there is a
difference in measured outcomes.
Mati Meron | "When you argue with a fool,
meron@cars.uchicago.edu | chances are he is doing just the same"
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| User: "Edward Green" |
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| Title: Re: basic question classical v. relativity |
13 Aug 2005 10:36:57 AM |
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wrote:
In article <1123844912_10855@spool6-east.superfeed.net>, "Herman Trivilino" <physhead@kingwoodREMOVECAPScable.com> writes:
<jmfbahciv@aol.com> wrote ...
None. See above. Both Newtonian and Einsteinian mechanics are
relativistic, the difference is in the rules governing transformations
between reference frames.
So each time we handle Newtonian mechanics we are really doing
"relativistic physics"? Hmm... :-)
I don't remember this being explicitly pointed out in any
of my physics classes. My recall has disintegrated quite
a bit, though.
Does this ring a bell? Newtons laws are valid only in inertial reference
frames. And when one works in noninertial reference frames one can invent
pseudoforces so that Newton's Laws can be applied as if one were in in an
inertial reference frame?
+
And one of the characteristics of pseudoforces is that they act on all
masses same way, meaning the resulting acceleration in a given place
and time is independent of the mass the force acts on.
It's sometime not clear where the pseudoforce lies. From a Newtonian
point of view gravity is a force, and as seen in a rotating frame a
pseudoforce is opposing gravity to keep an object in orbit. But from a
more modern point of view a body in orbit is subjected to no force at
all, whereas for an object on the ground seen in a reference frame
attached to the ground we introduce a pseudoforce (gravity) to explain
why the constant contact force does not result in constant
acceleration.
.
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| User: "" |
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| Title: Re: basic question classical v. relativity |
12 Aug 2005 02:24:35 PM |
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In article <FrGdnQyrw4M27WHfRVn-rQ@rcn.net>, writes:
In article <LHXKe.36$45.4610@news.uchicago.edu>,
mmeron@cars3.uchicago.edu wrote:
In article <1123817995.903921.123060@g43g2000cwa.googlegroups.com>,
zxcv_890@hotmail.com writes:
I took high school physics over the summer, and at the end we touched
on relativity, just a bit. This is probably overly simplistic, but
relativity seems to claim (among other things I'm sure) that you can't
just describe the motion of an object and leave it at that -- you have
to include the frame of reference that you took your measurement from,
because the motion of the object will measure differently depending on
your frame of reference.
Of course, same is true about Newtonian mechanics.
My question is, this seems like such an
obvious fact --I find it hard to believe that Newton (or at least one
of his followers) didn't realize this.
Of course he did. The first of the three laws defines an inertial
reference frame.
And if Newton did know this,
which frame of reference did he identify as the "true" one, and why?
None. See above. Both Newtonian and Einsteinian mechanics are
relativistic, the difference is in the rules governing transformations
between reference frames.
I don't remember this being explicitly pointed out in any
of my physics classes. My recall has disintegrated quite
a bit, though.
Well, it certainly wasn't pointed out in any of my high school physics
classes and even at the university it took a while before this point
was reached. There is a natural tendency, when introducing a new
theory, to go for "wow", you know, "all you've learned before was
wrong, now we do something completely different, etc. This is silly,
in fact downright couterproductive. There is a great deal of
continuity present between the various theories it it is much better,
IMHO, to point all that is common, then specifically enumerate the
differences. Then you can recognize what is truly new and what is
same stuff you already had before.
Mati Meron | "When you argue with a fool,
meron@cars.uchicago.edu | chances are he is doing just the same"
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