What Is Negative Time And What Does It Have To Do With The Possibility Of Time Travel?
Not long ago we published a post about a study scientists at the University of Toronto did. This study looked at how light travels through a cloud of atoms, and sometimes, the results seemed to show that the atom’s reaction occurred before the light hit it.
The researchers said that this occurred in ‘negative time.’
Not surprisingly, this got a lot of attention and people really wanted to know what negative time was, and how it may have the potential for traveling back in time.
First off, it is important to note that the study has not yet been peer-reviewed. It is available on the preprint server arXiv. So, it is still entirely possible that when the experiments are replicated, a defect in the study itself will be find to explain what happened.
If everything turns out to be accurate, it may reveal important information about how light works on the quantum level.
A co-author of the study, Josiah Sinclair, recently spoke with Scientific American and said:
“A negative time delay may seem paradoxical but what it means is that if you built a ‘quantum’ clock to measure how much time atoms are spending in the excited state, the clock hand would, under certain circumstances, move backward rather than forward.”
That may indicate that there is potential for this knowledge to be used for traveling back in time, right?
Unfortunately, no.
Sabine Hossenfelder is a theoretical physicist from Germany and after looking at the study, told his YouTube viewers:
“This negative time [in the experiment] has nothing to do with the passage of time – it’s just a way to speak about how a bunch of photons travel through a medium and how their phases shift.”
It may be that the scientists in the original study used the phrase negative time because it seems that the atoms react before the light gets to them, and that phrase would easily apply. It is also possible that they used that phrase knowing that it would attract more attention to their study.
Whatever the case, their findings have nothing to do with time travel. This is not at all to say they are not important.
If it turns out that they are accurate and they can find a way to fully predict and control how and when atoms will react like this, it could have a variety of practical implications. This may include things like how fiberoptic communication works, lasers, and many other things that rely on light for their applications.
I guess we won’t be traveling to the past anytime soon.
Too bad.
If you thought that was interesting, you might like to read about a quantum computer simulation that has “reversed time” and physics may never be the same.

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