How warp speed cuts you short ...

Wednesday, 29 August 2012

Time, someone once said, is mortality. It struck a chord with me because I had not until then considered that time has no meaning to an immortal.

Think about it: if you were going to live forever, you would be under no pressure to want to accomplish anything.

Neil Armstrong's death this week resurrected that thought process. It took me back to memories of sitting in my parents' flat in Essack's Building, Sparks Road, Overport, in Durban listening to the English Service of Radio South Africa (as SAfm was known then) carrying live audio of the Apollo 11 moon landing.

Space travel is all about time. Any distance can be covered if you have enough time to complete the journey. But the universe as we know it is so inconceivably huge that a journey to the closest star in our galaxy would, by my calculation, take 4,5 million years in a 747.

Even if one could travel at the speed of light, it would take four years to cover that distance. And we can't get there any faster because we can't travel faster than the speed of light.

Or can we?

The concept of faster than light travel – "warp drive" to Star Trek fans or "hyperspace" to Star Wars fans – has been an essential part of extra terrestrial science fiction since the genre came into existence.

So too has the concept of "wormholes" which are hypothetical gateways linking distant parts of the universe. Frank Herbert, author of the Dune saga, spoke of individuals developing the ability to "fold" space allowing for travelling without moving.

There are many dedicated scientists who spend their lives searching for that particular holy grail, hence the recent excitement around the putative discovery of neutrinos travelling faster than the speed of light.

Author Phillip K Dick first introduced me to the idea of why FTL travel might be possible. (Dick, if you are unfamiliar with his name, provided the original storylines for cinema success stories such as Blade Runner, Total Recall, Minority Report, The Running Man, and many many more.)

It was in a less-known short story called The Variable Man that he described the Fitzgerald-Lorentz contraction.

The premise is that as our speed increases, our length decreases.

So if I were travelling at, say, 240 000 km/second (80 percent of the speed of light), a 30 centimetre ruler in my hand would have shrunk to 18 cm.

So what? Well, it turns out that the formula to calculate one's length is linked to the speed of light.

And when one actually reaches the speed of light, the length of that ruler is zero.

What does that mean? Does it cease to exist? Does it wink out of our universe into another?

We don't know yet. Dick's storyline postulated that it would allow for faster than light travel – if we could work out how to ensure that when we slowed down enough to rematerialise, we did so in empty space and not in the inside of a planet.

So let's put faster-than-light travel aside for now and ask, how far can we travel with known technology?

Let's say we powered a spaceship at constant acceleration equivalent to Earth's gravity. You would need enough fuel for just about one year to get you close to the speed of light.

So, all we have to do is wait for the nuclear physicists to develop a controlled fusion reactor because fusion requires very small amounts of hydrogen as fuel.

Pack a craft with enough food and water and entertainment for eight years, and we'll head off to the nearest star, check it out, and come back.

Except there's another inconvenient reality called time dilation.

From the point of view of the folks back home, thousands of years would have passed during your first year of travel.

Inasmuch as your length shrinks relative to people back home, you will see a contraction of the universe in the direction of your travel.

So the only reason why we need faster-than-light travel is to try to find a way to travel to distant places and come back to tell the tale to people who saw us embark on the journey.

So if you are prepared to give up on the world as you know it today and come back thousands of years into the future, you can see much of the universe – hundreds of light years away.

But everything that you knew and loved would be long dead and gone. Space is time, and time is mortality.

Would you do it?

Farewell, Neil Armstrong. Thanks for the dream.