Thought experiment to compare the present with the future flow of time

Click For Summary

Discussion Overview

The discussion revolves around a thought experiment comparing the ticking rates of clocks placed in different environments, specifically a Faraday cage containing cosmic microwave background (CMB) radiation and a microwave oven. The participants explore how external conditions, such as temperature and radiation, might affect the passage of time as measured by these clocks.

Discussion Character

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

Main Points Raised

  • One participant proposes a scenario involving a perfect Faraday cage containing CMB radiation and questions whether a clock inside would tick at the same rate as clocks outside in the future when the CMB's redshift increases.
  • Another participant agrees with the assumption that gravitational effects can be neglected in this scenario.
  • A follow-up question is raised about the ticking rate of a clock inside a microwave oven compared to one on the casing, assuming gravitational effects are also neglected here.
  • Further discussion questions the qualitative differences in ticking rates between the two scenarios, particularly in relation to temperature changes of the CMB over time.
  • One participant clarifies that tick rates are numerical and suggests that differences in ticking rates due to environmental factors would be minimal, emphasizing that the effect of the box or oven would be significantly larger than any differences caused by radiation spectra.
  • Another participant inquires about the ticking rates of clocks in the context of the CMB's temperature change from 3000K to 2.7K, while again neglecting gravitational effects.

Areas of Agreement / Disagreement

Participants generally agree on the neglect of gravitational effects in their analyses, but there is no consensus on the implications of temperature and radiation on the ticking rates of the clocks. The discussion remains unresolved regarding the qualitative differences in tick rates between the two scenarios.

Contextual Notes

The discussion includes assumptions about neglecting gravitational effects and the impact of radiation on clock rates, which may not be universally accepted or applicable in all contexts.

witold
Messages
4
Reaction score
0
Let's assume that we can build a kind of a perfect Faraday cage 1x1x1 meters, which contains today's cosmic background radiation with its peak wavelength and density. Radiation in the cage cannot escape from it, and the external radiation cannot penetrate it. Now let's mount the perfect clock in the middle of the cage, place the cage in the intergalactic space and start the clock. Will it show the same time and tick at the same rate as the clocks outside the cage in the distant future, when the CMB's redshift will be twice as large as it is today? The clocks outside the cage are also started today and they are also in the intergalactic space, next to the cage.
 
Space news on Phys.org
Yes, assuming we can neglect the gravitational effect of the mass of the box itself.
 
Extra question: Does the clock placed inside the microwave oven tick slower than the one on the casing, that measures the baking time?
 
Yes, assuming we can neglect the gravitational effect of the mass of the microwave oven itself. And that the microwave doesn't damage the clock inside.
 
Is there a qualitative difference between the Faraday cage with the cmb radiation in the first case, and the microwave oven in the second in terms of the clocks ticking rates? In the first case we can wait for the external cmb's temperature to drop to 0.001K, but inside the cage it will still be 2.7K.
 
Last edited:
What do you mean by a "qualitative difference in tick rates"? A tick rate is just a number.

Basically, the tick rate of an ideal clock is not affected by the presence of microwaves around it. Two clocks can acquire different tick rates due to inhomogeneity in the matter around them, which is why I assumed we were neglecting the mass of the box/microwave. If you want to put that in the effect would be one part in ten to the twenty-something, and the effect of the box is many orders of magnitude larger than any difference due to the energy of the radiation inside the box, let alone any difference in that die to the different radiation spectra. They might acquire a fraction of a second difference over the period waiting for the CMB temperate to drop by half, but there definitely wouldn't be a factor of two difference in their elapsed times.
 
Ibix said:
They might acquire a fraction of a second difference over the period waiting for the CMB temperate to drop by half, but there definitely wouldn't be a factor of two difference in their elapsed times.
How about the difference in the ticking rates of the clocks outside the cage today and the clock inside the cage that captured the cmb at the temperature of 3000K at the moment of its emission and it's still with us today, when the cmb's temperature outside the cage is 2.7K? I neglect the gravitational effect of the cage.
 
Last edited:
It turns out that this OP is a sockpuppet of a temporarily-banned member, so this thread is now closed.
 
  • Like
Likes   Reactions: Ibix

Similar threads

  • · Replies 2 ·
Replies
2
Views
1K
  • · Replies 13 ·
Replies
13
Views
7K
  • · Replies 9 ·
Replies
9
Views
5K
  • · Replies 39 ·
2
Replies
39
Views
9K
  • · Replies 13 ·
Replies
13
Views
4K
  • · Replies 28 ·
Replies
28
Views
7K
  • · Replies 4 ·
Replies
4
Views
1K
  • · Replies 19 ·
Replies
19
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 1 ·
Replies
1
Views
9K