No. A time reversed parabola pointing down is still a parabola pointing down. Time reversed gravity is still attractive.Not A Physicist said:For example: wouldn't gravity have to start repelling matter?
It turns out, if you work through the math, that velocity reverses but acceleration remains the same.Not A Physicist said:It seems to me that if the arrow were to be reversed this would necessitate a reversal of the forces' ability to attract or repel.
I understand that, but if time started running backwards wouldn't gravity slow it down and pull it back around to its usual direction?Dale said:No. A time reversed parabola pointing down is still a parabola pointing down. Time reversed gravity is still attractive.
It turns out, if you work through the math, that velocity reverses but acceleration remains the same.
Sorry. It seems to me that if all particles had their velocity reversed, gravity (and the other forces) would just bring many of them to a halt and turn them around again, with the result that nothing much changed.Dale said:I don't understand what you are asking. It seems like I already answered that question. Can you please clarify?
Yes, that is correct.Not A Physicist said:Sorry. It seems to me that if all particles had their velocity reversed, gravity (and the other forces) would just bring many of them to a halt and turn them around again, with the result that nothing much changed.
The arrow of time is a concept in physics that describes the direction in which time flows. It is based on the observation that certain physical processes only occur in one direction, such as the expansion of the universe and the increase of entropy.
The forces that define the arrow of time include gravity, electromagnetism, the strong and weak nuclear forces, and the Higgs field. These forces govern the behavior of matter and energy in the universe and contribute to the directionality of time.
The arrow of time is closely related to the second law of thermodynamics, which states that the total entropy (disorder) of a closed system will always increase over time. This is because the arrow of time is driven by the tendency of energy to disperse and become more evenly distributed, leading to an increase in entropy.
In most physical processes, the arrow of time cannot be reversed. This is because the laws of physics are symmetrical with respect to time, meaning they do not distinguish between the past and the future. However, there are a few exceptions, such as certain subatomic particles that can behave differently when moving backwards in time.
The arrow of time is closely linked to causality, the principle that an event must occur before its effect. In a universe without an arrow of time, causality would not hold true, leading to a breakdown of our understanding of cause and effect. This reinforces the idea that the arrow of time is an inherent property of the universe.