# Tag Info

Accepted

### Have researchers managed to "reverse time"? If so, what does that mean for physics?

First of all, let's get some important 'sociological' aspects out of the way: While website you've linked to, phys.org, tries to pass itself off as a science-journalism site, it is nothing of the ...
• 124k

### What is time, does it flow, and if so what defines its direction?

What do physicists mean by time? We’ll start with the easy question what do physicists mean by time. Note that it’s easy to get mixed up between the concepts of time and the flow of time. When non-...

### Can a broken egg spontaneously reassemble itself (as in the video)?

No, it's not possible. See, there's a problem with the English word "possible": it's an English word. Even in the best cases it's hard to translate technical, scientific ideas into English ...

### Can a broken egg spontaneously reassemble itself (as in the video)?

It's possible, but won't happen anywhere within even one universe lifetime, not even close. Physicists often hate saying it is technically possible because the process is so mind bogglingly unlikely, ...
• 10.9k
Accepted

### Can a broken egg spontaneously reassemble itself (as in the video)?

Up to the limits of our theoretical understanding, yes, there is nothing in principle wrong with seeing what happens in the video happen for real in the sense that you can formulate this entire ...
• 17.3k
Accepted

### In reverse time, do objects at rest fall upwards?

The direction of the gravitational force would not change under time reversal. Your object would feel a force downward, just as it does usually. It might be easier to imagine you had a movie of an ...
• 11.4k

### How would the laws of nature behave if we reversed time?

Good question. Let's first consider the ball falling immediately before it hits the table. Neglect friction with the air for simplicity. The ball has a velocity in the downward direction. If we ...
• 1,256

### Time is the only dimension that has an arrow, and the only dimension which contributes an opposite sign to the metric. Is that just a coincidence?

Minkowski spacetime is a mathematical model constructed to capture aspects of the phenomena we observe. It is a product of the human imagination, like all of our models of physics. The observed fact ...
• 4,103
Accepted

• 4,265