Confused about the logic of a Special Relativity problem

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The discussion revolves around understanding time dilation and the Doppler effect in the context of the twin paradox in special relativity. A pharmacist seeks clarity on how the traveling twin appears to age slower while also questioning the implications of light travel time and visual perception during the journey. Key points include the distinction between what the Earth-bound twin observes and the actual events occurring, emphasizing that the traveling twin is never ahead of the light emitted from her. The Doppler effect is explained as the phenomenon where the frequency of light changes based on the relative motion of the source and observer, leading to perceived acceleration in the traveling twin's actions. Ultimately, the conversation highlights the complexities of relativity and the importance of separating observational effects from actual time and distance measurements.
  • #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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