We experience time as a one-way street. Within spacetime, we experience four dimensions: three spatial and one forward time dimension. Einstein’s theories show time can bend under gravity, and jumping into the future is likely possible. So, yes, time travel in that sense is possible, and proven. However, that’s not what most people are asking. The key question is can we travel back in time, and that appears to be impossible. Traveling to the past remains a paradox in physics, wrapped in the mysteries of spacetime.
So far, observations show that spacetime only bends in ways that preserve causality.
From a philosophical viewpoint, the interesting thing is that if it is possible, it is possible now. The needed materials and ideas are in the universe now, awaiting our discovery. To push the boundaries of this idea a bit, some solutions to Einstein’s general relativity equations suggest closed time-like curves, enabling travel through time. Despite these philosophical and speculative notions, most scholars say no, traveling back in time is not possible. It appears the laws of physics do not permit time travel to the past, and none of our observations to date support the idea.
1 thought on “Does time travel exist?”
From Facebook, July 2024:
Comment: traveling forward is also impossible. One can plausibly leap forward some years however, one cannot plausibly move a day, days, a months or even just a year forward. Therefore leap would be a better descriptor.
Me: I understand your point about why travel a day or month into the future when you can’t come back, seems silly, but I’d also argue that even using the term “leap” might be misleading when it comes to time travel. Leaping implies a sudden, bound-like movement, whereas time travel, according to relativity, is a more continuous transition through time.
As for traveling a year versus many years, I’m not sure I understand your point. If and when we have the technology, traveling a year, or fifty years into the future is just a matter of calculation. Anyway, interesting stuff.
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Comment: …short leaps are not possible, only decades or longer…
Me: …from the point of view of the traveler, his spacetime area around him is “normal.” He does not experience it as a leap or change of any kind. It’s only when he returns to a previously known spacetime that he can learn that more time has passed for those left behind than he experienced.