Is time travel possible? Can we send messages back in time? Can we talk to our future selves?
These are questions that have been widely debated among scientists for a very long time.
"Time is a dimension, but it's so unsual in that sense that we can only move forward in it as long as we are in our Universe.
We try to find ways to travel back in time, but by doing that we are affecting a very important part of our physical Universe, called causality. If we want to
travel back in time, we must find a way to prevent causality from being violated," astrophysicist Charles Liu
It is without doubt a controversial subject and few will accept such claims without a lot of hard evidence.
Nevertheless, the topic remains fascinating and worth consideration.
Instead of thinking about transporting ourselves back in time , or to the future, we can ponder another more realistic subject - namely time travel communication.
Dr. John Cramer, professor Emeritus of Physics at the University of Washington thinks we must think about time travel in baby steps.
One possibility is to start with messages traveling through time.
Dr. Cramer is currently working on the possibility receiving a message milliseconds before it's sent.
He is conducting his research in the basement at the University and with help of laser beams he might be able to prove what Einstein called "spooky action at
a distance". He's splitting photons through a series of synthetic crystals to demonstrate that quantum non-locality can be used to communicate.
"I have to admit, this is pushing the envelope and often the envelop pushes back," says Cramer, a nuclear
physicist who has worked on projects involving the Large Hadron Collider in Switzerland.
Is it possible to send messages through time?
For those of us who never took high school physics, this is what he's trying to do in layman's terms: If you took a pair of photons created at the same time and
altered one of those photons, in theory the other photon would be altered instantly -- even if it was separated by an entire galaxy.
That would mean communication could travel faster than the speed of light over long distances. The ramifications of something Einstein didn't think was possible
but theoretically could happen would be incredible. Physicists call it "nonlocal quantum communication."
"You could do real-time communication with objects on other planets," says Cramer. "You could put on a virtual reality helmet and be driving
your remote dune buggy on Mars."
In other words, this would give the world's space agencies the possibility to communicate with their spacecraft in real-time.
Unfortunately, Dr. Cramer is struggling with not only technical, but also financial problems. Funding of his project is a difficult matter.
"You have to be able to efficiently detect the entangled photons before you can do any real measurements and we have not been able
to do that yet," says Cramer.
According to "the original string theory, bosonic string theory, contained a massless particle called the tachyon, which travels
faster than the speed of light. These particles are usually a sign that a theory has an inherent flaw - but what if they actually existed?
Would they allow a means of time travel?
The short answer is that no one knows. The presence of tachyons in a theory means that things begin to go haywire, which is why they're considered by physicists
to be a sign of fundamental instabilities in the theory. (These instabilities in string theory were fixed by including supersymmetry, creating superstring theory.)
However, just because tachyons mess up the mathematics that physicists use doesn't necessarily mean that they don't exist. It may be possible that physicists
just haven't developed the proper mathematical tools to address them in a way that makes sense.
If tachyons do exist, then in theory it would be possible to send messages that travel faster than the speed of light. These particles could actually
travel backward in time and, in principle, be detected.
To avoid this problem (because, remember, time travel can destroy all of physics!), the physicist Gerald Feinberg presented the Feinberg reinterpretation
principle in 1967, which says that a tachyon traveling back in time can be reinterpreted, under quantum field theory, as a tachyon moving forward in time.
In other words, detecting tachyons is the same as emitting tachyons. There's just no way to tell the difference, which would make sending and receiving
messages fairly challenging," Andrew Zimmerman Jones and Daniel Robbins write in their book
String Theory for Dummies.
If Cramer can prove step one, step two becomes even more fascinating.
"If you can communicate using non-locality then you can communicate faster than light and backwards in time," says Cramer.
"I'm a little scared of what happens if it does happen because the implications are so bizarre."
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