Time travel is the concept of moving between different points in time in a manner analogous to moving between different points in space. Time travel could hypothetically involve moving backward in time to a moment earlier than the starting point, or forward to the future from that point without the need for the traveler to experience the intervening period. Any technological device – whether fictional, hypothetical or department store – that would be used to achieve time travel is commonly known as a time machine. This is all very obvious but Time Travel isn't so hard and they make the machines. Modern science has many time machines. The camera was the first one I can think of and just recently I looked at photos I took ten years ago and it made me time jump to the day. My wife has old slides from her father and when I look at them I get to see my wife at a point in time before I knew her. Sure you can argue that it's not pure time travel but if you ever get misty eyed at an old photo, your kidding yourself if you didn't just go through time.
Next is the telescope. Yes, it is hundreds of years older (17th century, think Galileo Galilei's time), orders of magnitude more powerful but it can see into the past before any of us were around. It's a camera that can take pictures today that are 13.3 Billion years old. They are often referred to as Ultra Deep Field images. That means 13.3 billion years ago a giant ball of hydrogen, compressed into a plasma, ignites into a star and started emitting light. The photons traveled though space without changing for billions of years so the image the telescope gets was the original photon image formed the day it was emitted. That just happens to be billions of years ago so that's a way to look into the past. The farther you look the older it gets. Our own sun is 8 minutes 19 seconds behind us. When you see it set, it's been down for 8 minutes. Look out and you're looking back in time.
The last is a scuba dive computer and my time machine of choice. It's a modern integrated circuit board programmed to understand human tissue under high pressure. Breathing underwater means calculations on counter diffusion, tissue saturation and the critical diameter of the gasses. Obviously we simplify that by using a chart that says if I go to 100 feet I can stay there for x minutes but better yet is a computer that monitors and report only the critical information to the time traveler, er, diver. Just as light travels through time so does a diver through water. Most of the debris on the bottom of lakes found it's home in the late 1800 or early 1900. If you want to see it you have to travel and a wrist mounted time machine makes the jump easier. Divers call a dive a Jump.
This brings me to a rare old shipwreck I travel to. I am one of the very few to ever see her. We were lucky to find the location. A buddy that loves to fish trolled the area all summer to find it on a sounder. Visibility in the summer is so poor you can hardly see your own hand so winter is the best time to go.
Everyone gets into a space suit and we cut the hole that will be our portal into time.
We travel about 30 feet down and go back 90 years to the day it sunk. For me to the craftsman that put her together. I wonder who intalled the planking? Who fell the trees? I can see the tool marks from both and that helps me see a time before I was born. A dive computer can bring you back in time like a telescope and a camera can freeze that moment for the future to enjoy and others to discover what we did back in good old 2013.
When you look at the photos of her it's not quite the same as being there but in ten years, I'll look at them and travel back to the day, I went back in time. And on that note, I need to get back to the present.