Originally posted 2020-05-17 12:46:27.
Flying out to the Phils a while ago I watched an excellent show presented by the late Professor Stephen Hawking about time travel. This has fascinated us for over a century, leading to all sorts of speculation about time machines. HG Wells’ eponymous book is perhaps the first and defining of the many books about this and, of course, the beloved Doctor Who is dependent on the notion.
Time and Space
Wells’ vision, however entertaining, overlooked one major problem with time travel: even if you could move to a different when, establishing where that would be is staggeringly complex. The Earth is not stationary, indeed nothing in the Universe is. You would need to calculate precisely where in space you wanted to be at the time you wanted to be there. Suppose you just want to go back a week. It’s not just a matter of going back a week where you are now, because last week, where you are now was 11.25 million miles away.
You’d pop back into time in space and spend eternity orbiting the sun as a block of pink ice.
The computing power required to get to where you want, whenever that was, is huge. And you need to be accurate. The slightest spatial error spells disaster. You might rematerialise a thousand feet in the air, without a parachute or, just as easily, a thousand feet underground, with no shovel. The difference between these points is measured in nanoseconds, on an object travelling around the sun at 67,000 miles an hour and with surface rotation of 1000 miles an hour. Try doing that in your head.
The Speed of Light
There are other issues. Hawking reiterated the basic facts we learned in school: time slows as one approaches the speed of light. It appears to be a built-in, immutable factor that prevents anything, ever, from exceeding the speed of light. As soon as an object approaches this velocity, its time slows, so it cannot go faster than light. It’s like the fantasy nightmare of the door that keeps receding the harder we run towards it. The great man suggested that this could allow a form of time travel and, as our lovely science teacher showed all those years ago, if we built a space-ship and travelled away from Earth till we reached as close as we could to the speed of light, then (somehow) turned round and came home, then, because our time would have slowed during the voyage, we would return far into the future.
But this isn’t really time travel. This is time cheating. Look at a similar situation. It takes around sixteen weeks to build a modern home, if the builders actually show up. Suppose we, most unwisely, set them to work and left for a month in the Dordogne as soon as they had poured the foundations. When we came back we should be impressed by the changes (should be: these are builders we’re talking about.) But it’s not so amazing, since the work should have been going on as usual while we were pissing it up on cheap rouge.
The near-light-speed spacecraft is similar: while we’re on it, our time is slowed while back on Earth, things carry on as usual. So it’s a manipulation of local time, rather than real time travel.
The future doesn’t exist
Actually moving forwards through time — that is, to build a machine that could simply squirt us, say, a day into the future, is probably not possible for the simple reason that the future doesn’t exist. We live on the cutting edge of creation. The universe is literally being created as we see it. We and everything around us, is coming into existence as we observe it. This is not anthropocentrism. Schrodinger’s Cat, both alive and dead till we open its box, proves the point. Reality is not fixed until the moment of its observation.
What is actually there, in front of me, twenty seconds into the future? That is a position in time that does not yet exist, therefore nothing in it can exist. Therefore the future itself doesn’t exist. There is nothing ahead of us, and not just the nothingness of empty space, real, honest-to-goodness nothing at all — in other words, not even empty space. Time is the advancing line of creation itself. So you can’t go into the future because there is nothing to go into. That is almost certainly why there is a phenomenon that prevents us reaching the speed of light. It’s almost as if there were someone smarter than we are.
Now, we don’t know what the nothing ahead of us is made of, but it seems unreasonable, to humans, to suggest it is actually nothing. We presume that there must be something there and it is from this something that the ordered universe we think we know is created.
Perhaps, on the other side of the event horizon that is reality, everything moves faster than the speed of light and it is only crystallised into an organised, observable reality for instant in which it can be observed — and then just as instantly decomposes back into chaos. But just as likely, there is absolute nothing. Zero. Zip. One microsecond ahead of where you are now, it is as if the Big Bang never happened.
The past doesn’t, either
When we look back in time, we do not see the event horizon. We see a record of its passing. It’s a bit like being overflown by a supersonic aircraft. You have no idea it’s there at all until suddenly BANG and there it is. Reality is the same: it’s only once it has happened that we can observe and study it. But just like the jet, what we’re studying is an echo, a trace left in passing. Reality itself is somewhere else. It has left the building.
In the night sky, the stars that we see are not there any more. They’re in another place, if they exist at all. The nearest star outside our solar system is Proxima Centauri, some 4.24 light years away. That means that it could blow itself to smithereens tomorrow and we would have no clue at all for another four years and three months, give or take. We’d assume it was still there, glowing dimly in the Alpha Centauri cluster. Even our sun, Sol, is not as we see it, for there is enough distance for it to have changed in the time, twelve minutes roughly, that it takes for light from it to reach us. What we actually see is like a newspaper photograph. It is a record of a previous event, one that is over and now exists only in the traces of its passing.
In short, that which has already happened no longer exists and that which is still to happen does not exist yet. Reality, therefore, only exists in the infinitesimal space that perception affords it.
Are we God?
Is Reality simply being created and just as quickly destroyed as we observe it, leaving behind only a record of its passing that we call memory? And are living things capable of remembering the only places where information about these events are stored? These are awesome concepts because they beg a question: is Reality just as it is because that is how we conceive it? And are we then responsible for reality itself? Do the Laws of Physics exist in the way they do because we observed and described them? Does the Prime Number Sequence actually exist or is it a function of our description? Are we the Creator, after all? When we created God in our image, were we closer to him or less so?
I found Dr Hawking’s lecture fascinating but I was disappointed that he did not tackle these thorny issues.