Newton - aware of relativity; who else?

Warren Moore · 2004-02-27T11:51:10

In Newton's Principia , Book One, he gives a definition of inertia containing the following line (assuming the translation is correct): "Resistance is usually ascribed to bodies at rest, and impulse to those in motion; but motion and rest, as commonly conceived, are only relatively distinguished; not are those bodies always truly at rest, which commonly are taken to be so." This pretty clearly indicates that Newton was aware of relativity between different reference frames, even if he didn't formulate tranformations between them (i.e. in terms of the Lorentz transform, as Einstein). The questions that naturally arise are: (1) Would anyone have been shocked by this seemingly trivial assertion? For while it seems intuitively obvious now, it also seems that many of Newton's contemporaries would not have intuitively thought of "relatively" at-rest bodies as in motion in another reference frame. Is that just because it complicates practical thought where such considerations are too tedious to account for (viz. high school-level physics)? (2) Who, if not Newton, first referred to the relativity of reference frames? (3) What was particularly radical about Einstein's conclusions in the special theory? Was he the first to formulate transforms between frames with Lorentz? It seems unreasonable, since he takes it as a given, and it seems to so precisely fit the situation (along with intuitively proving that the speed of light is constant in vacuo ). Later, ZE. //email me.//zealouselixir software.//msdn.//n00biez.//miscellaneous links [edited by - zealouselixir on February 21, 2004 3:37:30 PM]

Math and Physics Programming

Started by zealouselixir February 21, 2004 02:35 PM

33 comments, last by zealouselixir 20 years, 1 month ago

davepermen

1,047

February 27, 2004 08:08 AM

question:

for me on earth, the clock in the rocket ticks too slowly. so he ages less fast => he will be younger than i when he comes back. (if we were twins at the start)

you stated that the same effects happen for him, looking to me. flattened earth as i see the flattened spaceship. and he sees my clock going slower, too? if i got that right, i would be younger than him, once he''s back..

what have i messed up now?

If that''s not the help you''re after then you''re going to have to explain the problem better than what you have. - joanusdmentia

davepermen.net

If that's not the help you're after then you're going to have to explain the problem better than what you have. - joanusdmentia

My Page davepermen.net | My Music on Bandcamp and on Soundcloud

Anonymous

February 27, 2004 09:37 AM

quote:Original post by davepermen
for me on earth, the clock in the rocket ticks too slowly. so he ages less fast => he will be younger than i when he comes back. (if we were twins at the start)

you stated that the same effects happen for him, looking to me. flattened earth as i see the flattened spaceship. and he sees my clock going slower, too? if i got that right, i would be younger than him, once he''s back..

That''s the classic twin paradox. The difference is that the guy in the rocket must accelerate to get back, ie his frame of reference is not inertial.

davepermen

1,047

February 27, 2004 10:39 AM

that means, when he moves back, the time differences get moved back again? so will we be twins again? or will he be younger, or will i be younger?

it will not work that he is younger in my eyes, and i am younger in his eyes.

so what will happen? or wich one of the above is wrong?

If that''s not the help you''re after then you''re going to have to explain the problem better than what you have. - joanusdmentia

davepermen.net

If that's not the help you're after then you're going to have to explain the problem better than what you have. - joanusdmentia

My Page davepermen.net | My Music on Bandcamp and on Soundcloud

Cedric

158

February 27, 2004 11:42 AM

The rocket-bound twin will be younger. If it was the Earth that started speeding up to twice the rocket''s speed, when the two would meet, the rocket-bound twin would be older.

Cedric

158

February 27, 2004 11:49 AM

And in electrodynamics, we often say that the speed of light in a dielectric (such as water), is inferior to the speed of light in vacuum, c. v = c / n, where n is the index of refraction of the medium.

Light is an electromagnetic wave. Its speed depends on the properties of the medium in which it is propagating. This all comes from Maxwell's equations in vacuum, and in dielectrics.

Cédric

[edited by - Cedric on February 27, 2004 12:51:10 PM]

Newton - aware of relativity; who else?

This topic is closed to new replies.

Popular Topics

Recommended Tutorials

Newton - aware of relativity; who else?

This topic is closed to new replies.

Popular Topics

Recommended Tutorials

Reticulating splines