Time, distance, and so many questions

Questions that crop up in unexpected places, too. I'm sure any question I can ask is answered in a dozen places by a dozen knowledgeable people- my forays into the field are at the most basic "For Dummies" level that you can imagine. But, at any rate,it is all fascinating and illustrates just how little we really know about the big picture. It's amazing that, with all the things we've learned, there is a seemingly infinite number of things we are still learning. The latest bout of this realization was prompted by something I discussed with my 13 year old daughter while we were out looking at the sky one night. I asked her if she could spot Mars and point it out, which she did (from our viewpoint, it was almost directly beneath the moon and very bright on that night). I asked her how she picked it out so easily, and the cascade of questions started. It went something like this:
"It's right there, under the moon."
"Right! Good job. How did you spot it so easily?"
"Well, it's red, isn't it? There aren't many red things to look for. Except that one there (pointing at Betelgeuse). What's that? Another planet?"
"No, that's Betelgeuse. It's a star, and a huge one at that. But you're right, it's pretty red, too."
"Oh, OK. How far away is that?"
"About 400 or so light years (after digging frantically in my head to come up with a number that wasn't completely wrong). Not far by interstellar standards, really, but it's a long way."
"400 light years....what does that really mean?"
"It means a big number. Light travels at 186,000 miles per second. So, take that figure and multiply it by how many seconds are in a year. Then times 400 years. That's how far away it is, and the light we're seeing right now left Betelgeuse 400 years ago. You're seeing the past when you look at it."
".....how are we ever going to manage to go there? How fast can we travel?"

At that point is where things kind of tip over into inescapable territory. It's like walking across a seesaw- you reach a point where it tips from going up to going down, and no matter how far out you walk the far end stays down there. I don't have answers for the things that are unwrapped and presented for consideration past that point. That dive into the unsure waters of pure theory and speculation can be scary.

It does make for an enjoyable evening of mulling over, though. How will we ever manage to visit distant (by our Earthly standard) places? I want to believe we will- but there are problems, Herr Einstein's E=MC^2 being only one of them. We know that as velocity increases, so does the effective mass of the object being accelerated, until it reaches a point of diminishing returns and we run out of possible energy to drive it any closer to light speed. So, under the rules of our universe as we now understand it, near light speed travel may be possible- but we aren't going to leap past it. Even if the energy was available, could we engineer any craft able to withstand the forces and pressures that would be applied at those speeds? I think we'd need a little more than a carbon fibre and aluminum honeycomb at that point. And that's just the tip of the iceberg.

One of the things about faster than light travel that always gets my brain in a knot is the possible paradoxes. I know that the time dilation effect addresses this, but I can't help but think about it- it's one of those things that hurts your mind to think about, but keeps coming back to visit. if I left here, travelled to a planet 5 light years away at 1.1C, could I then, 6 months after landing, go back to the pad and see myself arrive? No, of course not. But could I, with a powerful enough visual aid, look back and see the launch that started my voyage? Isn't that still very paradoxical? maybe not- particles do it. We know that a single particle can exist in two locations at the same observed time, so what's stopping us from exhibiting the same behaviour? Is it just that we can't move fast enough?

That darn seesaw just keeps tipping downward.