Not being a physicist nor playing one on TV, I have a problem with the whole Relativity time shift. Reading a lot of sci-fi in my youth from the masters, I still can't comprehend how moving away from Earth at light speed would result in the spacecraft having a different time differential to the Earth.
I don't believe time is an actual dimension, but a concept devised by humans on their white board math calculations. All the black hole and worm hole theories of bending time and space are just that - theories.
Not trying to be a flat-worlder, but no one has proven what a black hole is. If it's a imploded star that has so much gravity and won't allow light to escape, how can they even suppose what's beyond the Event Horizon? Movies like the recent, "Interstellar" tried in a convoluted way to make sense of black hole and how they could travel from one galaxy to the next. The premise was that humankind had learned in the far future that gravity is another dimension and created the black hole for mankind. Good movie, but non-sensical.
So I ask all the theory physicists what is time? Is it real or just a figment of human imagination? And if real, why can't space/time be bent to allow for travel backwards, which has never been the case or we would have seen it in our time? The movie above tried to explain it, but it was a movie.
You can ask those questions again!
Physicists (I'm not one) don't know what time is, for sure; but are sure time is not "everywhere the same." For example, the notion of "at the same time" is relative to observers. What one observer views as events occurring at the same time, another observer will see as one before the other, and a third observer will see the other before the one.
Time is real enough, but it just isn't what we intuitively think of it as. It would exist even if humans didn't.
"Travel backwards" can be thought of as a relative term too. In the two twins paradox, the twin that traveled and returned has aged little. From the perspective of the stationary twin, the traveling twin has traveled backward in time, even though neither twin experienced any reversal of time.
But why literal "travel backward in time," although theoretically possible at a particle level (nuclear reactions have no time arrow, and are valid in both directions), is not observed, I know of no explanation "why." Just that the result of aggregation of all these time arrows is "in a closed system, entropy or disorder must increase."
Not being a physicist nor playing one on TV, I have a problem with the whole Relativity time shift.
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Relativity was based on experimental results, and has been confirmed by experiment ever since its publication numerous times to ever greater precision. The same can be said for quantum mechanics, which is even stranger than relativity. It’s so strange that even its founders like Einstein and Schrodinger had difficulty accepting it.
“All the black hole and worm hole theories of bending time and space are just that - theories.”
Everything in science is a “theory”. Newton’s laws are theories. All scientific theories are man made models that try to represent how things in the real world work. If they are a close enough representation of reality than we humans can play (experiment) with the models and perhaps come up with ways to manipulate reality for our benefit.