Can We Travel in Time?

Yes, wait...

We are traveling in time.

We have no problem going forward and we have proved that ad infinitum. We can also vary the rate by which we move forward based on gravity and velocity experiments.

Going backward seems to be a problem; at least until you become senile. Then, it is said, you go backward quite readily.

I would say, "We travel with time" rather than, "We travel in time".

The future must be undefined unless we throw away the book of quantum mechanics and return to determinism.

If we return to determinism, our radios, televisions, computers, etc. would cease to exist, to never have been.

If our radios, televisions, computers, etc. ceased to exist, could we still build a time machine?

Would we still have lemonade under the front porch? Maybe it wouldn't matter, then.

Modify part of, "The Old Vicarage, Grantchester, by Rupert Brooke

Stands the Church clock at ten to three?
And is there honey still for tea?

To; And will there be honey still for tea?

Another one;

I always fear that creation will expire before teatime. ~Sydney Smith

These come from here So much about the pleasures of drinking tea.

<...We are traveling in time....>

- and at the speed of light.

<...proved that ad infinitum...>

Er, not quite. Proved it up until whenever and wherever the observer is in 4-dimensional spacetime.

Here's one place I'd consider going:

The Third Level

That was more ON TOPIC than any.

http://www.youtube.com/watch?v=X8iFholCpKo

Rough as guts but still ahead

Not long ago there was a time machine for sale on ebay that was manufactured (will have been manufactured? was to have been manufactured?) in the year 2239. It must be real, it has a plate with an inscription that says "Time Machine" on it.

I see the ebay listing is no longer valid; some must have bought it... was going to have bought it... will have bought it... I don't know, it's gone now.

And now, twenty seconds later, it is still gone.

(This originally offered by Nighthawk on 17 March 2005)

Count your blessings! I heard that it is a real load of crap and all it does is attract a lot of time flies. It's a faulty model and will soon be discontinued last year.

ebay? How times have changed for KrisDel^TM.

Some possible time travel fantasies:

1. Go back to Archimedes's time, and add just a few things so that he could create integral calculus nearly 1800 years before Newton and Leibniz.

2. Go back to the times of Buddha, Jesus, Muhammad, Joseph Smith, et. al., and actually document the origins of those religious movements.

The Twain was never meant to meet.

Last year I read a great book on this subject: "the Arrow of Time", by Peter Coveney and Roger Highfield. They propose that time is a vector moving only in one direction, and that the past is immutable. They make arguments by reviewing major scientific and historical events to "prove" that time is real (some scientists/mathematicians still doubt that), and that it is undirectional.

Not if the research I've studied is correct.

This research finds that time is an illusion that the whole physical universe has agreed to. Exit the physical universe and the illusion becomes obvious.

According to this theory, the illusion of time is created by setting up an automatic system that constantly re-creates all that we perceive. Where life organizes matter and energy, a coherent record of past events can be produced. But they are only records. Thus, you can locate such a record, or even destroy it, and in a sense "travel into the past and change it" but it is really only a very convincing recording of the past that you are changing.

There are persistent reports from the paranormal community that we have been visited by "beings from the future." Per this theory that could not really happen. The "future" has yet to be created. My answer for what is really happening in these reports has to do with the fact that new events tend to pattern themselves on prior events that exist as recordings. Thus if one has sufficient data about the past one can make a quite good prediction of what is likely to be created, even thousands of years ahead of time. So someone with this technology could convince us that they were from the future because they would be able to "predict it" with pretty good accuracy.

What you are really doing when you "change the past" is to change the pattern on which the future tends to be built. Therefore, in a way that seems almost mechanical, the future can be "changed" by changing our records of the past, or possibly just our understanding of them.

So far this theory has only been tested and used on a relatively small scale. But it is the one that makes the most sense to me.

The situation you are talking about is known in the world of physics as "The Problem with Time".

One proposal is that time simply does not exist. I'll talk more about this later. Actually, that is a cop out and gets me totally off the hook if time does not really exist! Later, ha!

In every branch of physics, Newtonian, Einstein, quantum, etc., take any equation you would like, you will find that those equations work just as well with time moving forward as they do with time reversing and going backward. There are no laws of physics preventing time from running backward.

So, why is the transmission of time seemingly stuck only in "Drive" and not able to be engaged in "Reverse"? Do we need a Quantum Mechanic to service our transmissions?

The concept of the absence of time is consistent with the Wheeler-DeWitt equation. Time is bounded within the/our Universe, but does not or is not an absolute entity. We can't measure time. Clocks do not measure time. Time is merely defined by the tics and tocs of our clocks; be them grand-farther, atomic, digital wrist watches, or in some cases, Cuckoo clocks.

Time is simply not observable and therefore not measurable.

Time may not exist at all except in the macro world. It may just be the stuff of perception in our minds and meaningless outside of that. That would seem to say that time travel is not possible; that is, if it does not really exist...

Yet, time travel is alive and ticking in the universe of fiction. There countless books on the subject where you can travel to any place imaginable or even unimaginable.

If you can't find a read that you like you are certainly open to write your own and travel anywhere you might fancy to go.

If time is simply our own illusion, then time travel is clearly possible and as unbounded as the infinity of our imaginations. How do you like that?

Do you have any references for this that have received qualified critical review?

You wrote, "Recent experimental evidence suggests that the aggregate universal speed limit - the speed of light in a vacuum - also applies to individual photons. Previously, many physicists believed that individual photons could exceed that speed."

I would like a link to that claim.

I recently read where there is evidence of differing speeds for different energy photons, although the difference was very small.

If memory serves, the difference was detected by comparing photons from very, very distant galaxies where the time traveled was very long, thus amplifying the difference in arrival time. I do not know the specifics of that experiment and how they came to that conclusion.

Your citation would seem to counter that claim.