I just came across this story about a physicist who took his family on holiday and travelled 22 nanoseconds in time.
As a collector of vintage and modern atomic clocks, I discovered it was possible, using gear found at home, to convert our family minivan into a mobile high-precision time laboratory, complete with batteries, power converters, time interval counters, three children, and three cesium clocks. We drove as high as we could up Mount Rainier, the volcano near Seattle, Washington, and parked there for two days. The trip was continuously logged with the global positioning system; the net altitude gain was +1340 meters.[/quote]

Quote :

Given the terrestrial blueshift of 1.1 × 10-16 per meter mentioned by Kleppner and integrating our altitude profile, we predicted the round-trip time dilation to be +22 nanoseconds. This is remarkably close to what we experimentally observed when, after we returned, the ensemble of portable cesium clocks was again compared with atomic clocks left at home.

http://jeffmilner.com/index.php/2007/03/08/an-adventure-in-relative-time-keeping/[/quote]
There is much current discussion with regard to the Cern Large Hadron Collider experiements as to whether a wormhole might be created which would create the possibility of time travel back to the point in time at which the wormhole came into being.

In terms of the science, are we nearly there yet? Can we expect the arrival soon of time travellers from the future ?

And in terms of interpersonal relations, what might they say to us ?

For time travel to happen every movement of every atom every nanosecond would have to be recorded because it all has to be reversed in order for us to travel back in time. Forward in time maybe I'd stomach via travelling at high speeds which is a form of suspension in that it preserves your cells in a seperate time bubble or time frame but needs massive energy too. Even then you only experience contracted time with reference to the slow feckers outside your ship for whom time runs normally.

So to go back in Time every movement of every etc. would have to be recorded somewhere in the universe so it can all be reversed. That's a mechanical view of the universe of course, usually at odds with the quantum one but even then the quantum universe is so speculative and creative and unverifiable that you can invent anything such as exotic entities like multi-universes, 26-dimensional space and quarks.

Never going to happen then ?

No - at least I hope not.

When you travel at high speed then the thing that makes time personal for you runs at a different rate. Time doesn't exist in your watch, a caesium atom or the sun it is only the idea of periodicity or oscillation that exists in everything in an inter co-ordinated way. The crystal in your computer/watch pulses at a certain rate under certain conditions and that's often taken as a faithful representation of time, if not the most faithful. (the motion of the earth is better no?) Your body also has an internal clock dictated by genes and the rate at which it pulses is also determined by the environmental conditions which are normally very stable.

However, what if you could change the rate of oscillation of your caesium watch and computer and also change the rate at which you cells are getting dictated to by your genes/DNA to run themselves down? Wouldn't it appear that time for your was now different for me? Your computer and your watch would all show a few minutes earlier and your cells would be less decayed than mine; wouldn't that be time distortion and if amplified wouldn't it be a form of Time travel - going in one direction, forward? Wouldn't you like to be able to do this? Well you can, simply by going on an airplane spin across the Atlantic or somewhere as we were told in Leaving Cert.

High speeds change those rates that time ticks at, also, different gravitational fields change the rates too... More gravity, slower time. Mars, less gravity than earth, computer clocks there run faster; Jupiter higher gravity so clocks run slower.

I've just put two giggling preteens - 11 and 12 and neither my own - to bed and I feel like I've been in a parallel universe all day. Time travel? Tell me about it

Kate P wrote:

I've just put two giggling preteens - 11 and 12 and neither my own - to bed and I feel like I've been in a parallel universe all day. Time travel? Tell me about it

Tuh! I had to carry my cousin's two girls around a field the other morning (chasing hens), one's eighteen months and a kicker, the others the guts of three. It's at the point where it's still feasible to carry them but very stupid.