Confused about the logic of a Special Relativity problem

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SUMMARY

The forum discussion centers on the complexities of time dilation and Lorentz contraction as illustrated by the twin paradox scenario involving relativistic travel to Alpha Centauri at 0.6c. The Earth-bound twin perceives the traveling twin's aging process at a different rate due to the Doppler effect, which causes the light emitted by the traveling twin to appear blue-shifted as she approaches Earth. Key misunderstandings addressed include the distinction between the actual events and the observer's perception, emphasizing that the traveling twin is never ahead of the light emitted during her journey. The conversation clarifies that while time dilation slows the traveling twin's clock, the Doppler effect alters the frequency of light observed, leading to apparent discrepancies in perceived time.

PREREQUISITES
  • Understanding of Special Relativity concepts, including time dilation and Lorentz contraction.
  • Familiarity with the Doppler effect and its implications for light waves.
  • Basic knowledge of electromagnetic waves and their properties.
  • Ability to interpret relativistic scenarios involving observers in different frames of reference.
NEXT STEPS
  • Explore the implications of the Doppler effect in both sound and light waves.
  • Study the mathematical formulations of time dilation and Lorentz contraction in Special Relativity.
  • Investigate visual representations of the twin paradox through educational videos, such as those by Paul Hewitt.
  • Examine real-world applications of Special Relativity in modern physics and technology.
USEFUL FOR

This discussion is beneficial for physics students, educators, and anyone interested in the nuances of Special Relativity, particularly those grappling with the twin paradox and its implications on time perception and light behavior.

  • #61
jartsa said:
I see. When I'm trying to reverse a distant clock, by a sharp acceleration of myself, the clock starts to resist further reversing at some time. Or rather: the more a clock is reversed, the more it resist reversing. Thank you guys. It's clear now.

When I'm trying to reverse a distant clock, the clock tends to become a nearby clock, nearby clocks behave less weird than distant clocks.

That's how it works. It's the length contraction phenomenon. Very simple actually.
 
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  • #62
jartsa said:
When I'm trying to reverse a distant clock, the clock tends to become a nearby clock, nearby clocks behave less weird than distant clocks.

You don't reverse distant clocks. You don't even change distant clocks. You change reference frames, but you'll never be in a reference frame that observes or even sees clocks running backwards.
 
  • #63
Mister T said:
You don't reverse distant clocks. You don't even change distant clocks. You change reference frames, but you'll never be in a reference frame that observes or even sees clocks running backwards.
Maybe if I use scare quotes the error is not so severe.

So I'm looking at Earth that is 1000 ly away, I'm seeing year 3000 going on, and it is now year 4000 on Earth according to me. Then I accelerate to speed 0.99999999 c away from the earth. Now I'm seeing year 3000 going on, and it is now year 3000 on Earth according to me. As I'm seeing Earth without much delay, the Earth must be near.

The Earth "moved closer" and "reversed" as I accelerated.
 
  • #64
jartsa said:
Maybe if I use scare quotes the error is not so severe.

So I'm looking at Earth that is 1000 ly away, I'm seeing year 3000 going on, and it is now year 4000 on Earth according to me. Then I accelerate to speed 0.99999999 c away from the earth. Now I'm seeing year 3000 going on, and it is now year 3000 on Earth according to me. As I'm seeing Earth without much delay, the Earth must be near.

The Earth "moved closer" and "reversed" as I accelerated.

No that is not what happens. And you aren't paying attention to what was said in #53 and #57 of this thread.
 
  • #65
Nugatory said:
No that is not what happens. And you aren't paying attention to what was said in #53 and #57 of this thread.

It's not the same scenario as before, I curbed the "reversing".

How much can I tilt the line of simultaneity? Almost 45 degrees. As the wordline of light is tilted 45 degrees, the light that an observer is seeing left the light source about now, according to the observer, when observer's line of simultaneity is almost parallel to the wordline of light.
 
  • #66
Without going into all the detail, the explanation of what's happening during this "experiment" is badly worded. In fact it's just wrong. Comparing "times" is misleading because there is no shared moment, so shared now! Only when they are together do they share the same time and the same location, apart from that their times and locations are only truly comparable by reference to a combined space-time.
 
  • #67
Hey don't give up, most people even the experts only understand this particular "experiment" on a very superficial level. The explanation provided by your expert is misleading and in fact downright incorrect. Comparing the times between the two individuals is not possible, there is no shares moment, no shares now! Making time like comparisons is without reference to space is impossible. Only by reference to full space time coordinates is a comparison possible, and. It is neither a true time comparison nor a true space comparison but rather a blend of both.
 

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