Gravity and the Direction of Time

In summary, an article titled "Identification of a Gravitational Arrow of Time" was published in Physical Review Letters in October 2014, along with other articles in general interest science magazines. Although it initially seemed like a significant discovery, there has been no further mention of it after 2014. The authors acknowledged that their findings were limited and did not explain all arrows of time. As a result, the discovery was not considered to be generally applicable and did not gain widespread attention.
  • #1
White Rook
I recently read an interesting article published in Physical Review Letters in October 2014 - "Identification of a Gravitational Arrow of Time." There were also other articles in several general interest science magazines.
https://physics.aps.org/featured-article-pdf/10.1103/PhysRevLett.113.181101.

It seemed like it could be a big deal, but I haven't read anything else about it with a date after 2014. What happened? Did it turn out to be incorrect or unimportant? Were there rebuttals? Was no one interested? I am curious to know what happened next.
 
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  • #2
I do not in the slightest claim to understand the paper itself, but this section may elucidate why it didn't have bigger repercussions:

"We emphasize that in this Letter we make no claim to explain all the various arrows of time. We are making just one point: an arrow of time does arise in at least one case without any special initial condition, which may therefore be dispensable for all the arrows."

The way it sounds this is a very narrow result, and thus not generally applicable.
 
  • #3
rumborak said:
"We emphasize that in this Letter we make no claim to explain all the various arrows of time. We are making just one point: an arrow of time does arise in at least one case without any special initial condition, which may therefore be dispensable for all the arrows."

The way it sounds this is a very narrow result, and thus not generally applicable.

Thanks for the response. Articles are always full of qualifications like that. It still seems like it could be a big deal, even if it's only in a limited sense. I'd still like to know why it's not.
 

Related to Gravity and the Direction of Time

1. What is gravity and how does it affect the direction of time?

Gravity is a fundamental force of nature that causes objects with mass to attract each other. The direction of time is the perceived flow of time from past to present to future. According to Einstein's theory of general relativity, gravity is a result of the curvature of spacetime caused by the presence of massive objects. This curvature also affects the direction of time, as time moves differently in areas with varying levels of gravity.

2. Does gravity have an impact on the perception of time?

Yes, gravity can affect the perception of time. Due to the curvature of spacetime caused by gravity, time moves slower in areas with stronger gravity. This means that a clock in a strong gravitational field will tick slower than a clock in a weaker gravitational field. This effect, known as gravitational time dilation, has been observed and measured by scientists using atomic clocks.

3. Can the direction of time be reversed?

According to the laws of physics, the direction of time cannot be reversed. The arrow of time always moves forward, from past to present to future. This is due to the second law of thermodynamics, which states that the total entropy (disorder) of a closed system will always increase over time. This means that even if we were able to reverse the direction of time, the overall entropy of the universe would still increase.

4. Is gravity the only factor that affects the direction of time?

No, gravity is not the only factor that affects the direction of time. Other factors such as the expansion of the universe and the presence of matter and energy also play a role. In the early universe, the direction of time was likely influenced by the Big Bang, which created a state of low entropy. As the universe continues to expand and become more chaotic, the direction of time moves towards higher entropy.

5. Can the direction of time be altered or controlled?

At this time, there is no known way to alter or control the direction of time. The laws of physics dictate that time always moves forward, and reversing it would require a violation of these laws. However, some theories, such as the theory of quantum gravity, suggest that the direction of time may be reversible on a microscopic level. Further research and experimentation are needed to fully understand the concept of time and its relationship with gravity.

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