The 'Space' in time travel

July 18, 2020

I like simple experiments and champagne. So, I’ve combined two of my favourite things to see if time travel from the future to the past is possible. I’m throwing a party, a welcome reception for future time travellers.

This was a famous experiment conducted by Stephen Hawking in 2009 to test backward time travel.

Unfortunately, it concluded with the following statement.

What a shame! I was hoping a future Miss Universe was going to step through the door.

Back then I was a kid and it broke my heart, after all, travelling back in time was the greatest adventure. Hawking didn’t outright deny the possibility of backward time travel, but he was not optimistic. I won’t be taking you back in time, but I hope to rekindle the optimism(or maybe not).

First, let’s take a look at our time machine:

It takes a Human(Humans were harmed in this experiment) at location x₁, y₁, x₁, at time t₁ and moves them through space-time to a new location x,y,z at time t. In our case t < t1. And when we are talking about time travel, we are only talking about time, “space” is given no space. So, let’s talk about space.

Let’s take a look at Hawking’s invitation:

It has fancy typography, yet it is minimalistic. All in all a solid 8/10.

It describes the time and location of the event. The invitation describes the location in coordinates. But these coordinates are not absolute, they are dependent on the earth’s centre. And since we know that earth’s moving through space. The position of these coordinates is changing relative to all things, not under the control of the earth’s gravity.

I hope you get where I’m going with this. If you again look at out time machine image. I described after travel coordinates as x,y,z, and this is because they are not same as x₁, y₁, z₁. So, if anyone tried to travel back in time only, they would probably be left hanging in the void. This is a point which sounds so obvious, but I don’t see this mentioned anywhere. I can’t blame them, hell, it only came to me today.

To solve this problem, we need a way to configure the displacement of earth’s coordinate over time.

Let’s consider the movement of the earth through space:

1. Relative to the equator, the earth rotates counterclockwise at ~1670Km/Hr.
2. Relative to the sun, the earth orbits counterclockwise at ~10800 Km/Hr along a path 23.4° to its spin.
3. Within our local neighbourhood of stars, our entire solar system is moving ~70,000Km/Hr, in the direction of star Vega in the constellation, of Lyra.
4. Relative to the Milky Way, our solar system orbits clockwise at ~79200 Km/Hr along a path tilted at 60°.
5. Milky Way is moving along the direction of Leo and Virgo are to us at 2.1 million Km/Hr towards something called ’The Great Attractor‘(We don’t fully understand this).

All this results in a path like this:

Beautiful isn’t it!

Above image and the Speed stats, are the courtesy of the amazing Vsauce!

All this doesn’t cover everything, but still, in theory, we can put all this into our machine and calculate our new coordinates, right?

Well, maybe not, as in our calculations, we are taking our reference point as ‘The Great Attractor’. So we are assuming that ‘The Great Attractor’ itself isn’t moving which may or may not be true. Even a small movement by the Great Attractor will cause havoc to our plans. Also, all these speeds are just averages, even earth is not moving around the sun at the same speed all the time. On top of that earth and other celestial objects haven’t always travelled at the same speed. Small changes during interaction of large objects, due to collision or gravity affects these speeds, and these events are random. And if you stretch the timeline long enough, these small changes add up. And you only need to be off by about 100Km to miss the earth completely. And when we are talking on such massive scales, 100Km is pretty insignificant.

So, now the real question is, after knowing all this! If you were from in the distant future when time travel is invented, Would you have attempted to arrive at Hawking’s Party?

Also, feel free to challenge and poke holes into this.

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