Speed of light and length contraction

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Discussion Overview

The discussion centers around Einstein's assumption of the speed of light as a constant and its implications for length contraction, mass, and time dilation, particularly in the context of high-speed travel in space. Participants explore theoretical aspects, mathematical formulations, and conceptual interpretations related to these phenomena.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant seeks clarification on Einstein's assumption of the speed of light and its relation to length contraction, mass, and time dilation.
  • Another participant provides mathematical equations related to time dilation and length contraction, suggesting that using units in terms of the speed of light simplifies calculations.
  • A third participant references Brian Greene's interpretation of the relationship between motion through space and time, proposing that traveling at high speeds affects the rate of time experienced by the traveler.
  • One participant argues that Einstein's assumption of the speed of light as constant led to the discovery of relativistic effects, citing Maxwell's equations and the contradiction with Newton's laws as foundational to this assumption.
  • Another participant emphasizes that moving at high speeds does not affect the laws of physics, suggesting that local observations in a closed system cannot determine one's velocity.

Areas of Agreement / Disagreement

Participants express differing views on the implications of Einstein's assumption and the nature of relativistic effects. There is no consensus on the interpretation of these concepts, and multiple competing perspectives remain present in the discussion.

Contextual Notes

Some claims rely on interpretations of theoretical concepts and mathematical formulations that may not be universally accepted or fully resolved within the discussion.

Brookey
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Hey, I am new to this site, I'm not entirely sure where i should post this question but can anyone here help?
I need to know Einsteins assumption of the speed of light as a constant by referring to length contraction, mass and time dilation and how it affects people traveeling in space at high speeds...
Anyone?
Brooke
 
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when traveling at very high speeds:

To = T(sqrt(1 - v^2/c^2)) [To is stationary time, and T is the travellers time]
Lo = L(sqrt(1 - v^2/c^2)) [Lo is stationary length, and T is the length experienced
by the traveller]
Mo = M/(sqrt(1 - v^2/c^2)) [Mo is rest mass, and M is the travellers mass at high speed]

to do these calculations it is simple is you use units in c, (ex. 0.8c, 0.9c) and not in m/c. If you use c (speed of light) units, then the units cance out nicely and your answer can be obtained in 30 seconds.
 
The answer that I am about to give you is not my own but brian greenes from the fabric of the cosmos .
he states that when you are stationary you are traveling only through time but when you move you are traveling through both space and time.
now when you a stationary you are traveling through time at the spped of light but when you move some of this speed is transferred to traveling through space. this means that because the sum of traveling through space and time must always =c then the faster you travell through space the slower you must travel through time. hence time dilation.
hope this helps.
 
Both Nenad and jamie's answers were correct, however your looking at the problem backwards. Einstein didn't assume the speed of light is constant because of the previously mentioned relativistic effects, he discovered these effects because he assumed the speed of light is constant. This assumption comes from James Clerk Maxwell's equations for electromagnetism, which don't provide a frame of reference for the calculated speed of light, c. The conclusion (which was drawn by many before Einstein too) was that therefore light must travel at c relative to everything, contradictory to Newton's laws of motion. Therefore Einstein developed his special theory of relativity to show how it's possible for light to travel at c relative to everything, the explanation being drawn from such things as time dilation and length contraction.
Welcome to PF!
 
Brookey said:
Hey, I am new to this site, I'm not entirely sure where i should post this question but can anyone here help?
I need to know Einsteins assumption of the speed of light as a constant by referring to length contraction, mass and time dilation and how it affects people traveeling in space at high speeds...
Anyone?
Brooke

Moving at high speeds per se doesn't have any effect. The laws of physics are independent of one's velocity. So if one is in a closed spaceship, or a closed train, one can't tell from local observations whether or not one is even moving.

Of course, there are some practical issues, like the importance of avoiding collisions. Running into even a very small dust speck at relativistic velocities would be Bad. Without some more details, it's hard to say which of these practical issues would be important to you.
 

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