Galileo's relativistic postulate question

  • Context: Graduate 
  • Thread starter Thread starter bernhard.rothenstein
  • Start date Start date
  • Tags Tags
    Relativistic
Click For Summary

Discussion Overview

The discussion revolves around the implications of Galileo's relativistic postulate in the context of measuring the speed of light and bullets in a scenario involving two observers in relative motion. Participants explore how these measurements relate to classical and relativistic physics, questioning whether Galileo would agree with certain statements regarding the constancy of the speed of light.

Discussion Character

  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • One participant proposes that both observers would measure the speed of light emitted from their respective laser guns as c, regardless of their relative motion.
  • Another participant argues that Galileo would assert that the speed of light is c only for an observer at rest with respect to the light source, expressing uncertainty about Galileo's views on light speed.
  • A later reply suggests that the situation is symmetric, implying that both observers would agree on the measurement of light speed.
  • Another participant confirms that Galileo would agree with the statements, prompting a question about the observation of light speed from the other observer's laser gun.
  • One participant introduces a hypothetical scenario where they could derive relativistic effects without measuring the light speed from the other observer's laser gun, suggesting that time dilation and length contraction could be derived from the first postulate.

Areas of Agreement / Disagreement

Participants express differing views on whether Galileo would agree with the statements about light speed. Some assert that he would, while others argue against it, indicating a lack of consensus on this point.

Contextual Notes

Participants express uncertainty regarding Galileo's potential views on light speed and the implications of their measurements, highlighting the complexity of reconciling classical and relativistic perspectives.

bernhard.rothenstein
Messages
988
Reaction score
1
Consider the following statements:
1. If you move relative to me with velocity V I move relative to you with velocity -V.
Consider that I am equipped with a machine gun and with a laser gun at rest relative to me and you are equipped with identical machine gun and laser gun at rest relative to you. We are in relative motion with constant speed. If I measure the speed of the light emitted by my laser gun and the speed of a bullet fired by my machined I obtain c and u respectively. If you measure the speed of the light emitted by your laser gun and the speed of the bullet fired by your machine gun you will obtain c and u as well.
Would Galileo o.k. the two statements.
If yes I will continue.
 
Physics news on Phys.org
bernhard.rothenstein said:
If I measure the speed of the light emitted by my laser gun and the speed of a bullet fired by my machined I obtain c and u respectively. If you measure the speed of the light emitted by your laser gun and the speed of the bullet fired by your machine gun you will obtain c and u as well.
Would Galileo o.k. the two statements.

No …

Galileo would have said that the light from a laser gun goes at c only as measured by an observer who says the gun is stationary

(except I'm not sure he wouldn't have said it goes infinitely fast :redface:)
 
tiny-tim said:
No …

Galileo would have said that the light from a laser gun goes at c only as measured by an observer who says the gun is stationary

(except I'm not sure he wouldn't have said it goes infinitely fast :redface:)
Thanks.
I have mentioned that "my laser gun is at rest relative to me and that your laser gun is at rest relative to you. I measure the speed of the light signal emitted by my gun, you measure the speed of light emitted by my laser gun. As I see you aggree with the fact that we both obtain the same c. Can I consider that your answer is yes...?
I have in mind a modern Galileo being able to measure very short time intervals.
 
oh i see … then yes … the situation is symmetric anyway :smile:
 
"Would Galileo o.k. the two statements."
Yes. So is your next question, "Why do I observe the speed of the light from YOUR laser gun also as c?" :)
 
sganesh88 said:
"Would Galileo o.k. the two statements."
Yes. So is your next question, "Why do I observe the speed of the light from YOUR laser gun also as c?" :)
Good question.
Consider that I could imagine a scenario in which I not obliged to measure the speed of the light signal emitted by your laser gun and you are not obliged to measure the speed of the light signal emitted by my laser gun. If I could derive, following that scenario, the formulas which account for relativistic effect then I could consider that they are the result of the first postulate. It seems to me that time dilation and length contraction could be derived so.
 

Similar threads

Undergrad Why does laser beam hit the same target when fired?
  • · Replies 90 ·
4
Replies
90
Views
4K
Graduate Is the constancy of c a postulate or a derivable theorem?
  • · Replies 13 ·
Replies
13
Views
1K
Undergrad Understanding Einstein's second postulate of special relativity
  • · Replies 57 ·
2
Replies
57
Views
8K
Undergrad Energy and reference frames
  • · Replies 87 ·
3
Replies
87
Views
6K
Undergrad Relativistic Uniform Circular Motion
  • · Replies 15 ·
Replies
15
Views
1K
Graduate Potential Energy of Relativistic Particles in Coulomb Field
  • · Replies 4 ·
Replies
4
Views
2K
Undergrad Refractive index of a medium in relativistic motion
  • · Replies 14 ·
Replies
14
Views
4K
High School What is m in Kinetic Energy? Relativistic mass or Rest mass?
  • · Replies 55 ·
2
Replies
55
Views
6K
High School Length contraction of a pair of electrons
  • · Replies 54 ·
2
Replies
54
Views
5K
High School What Are the Relativistic Implications for Beacon Synchronization?
  • · Replies 25 ·
Replies
25
Views
2K