The Iconoclast: Imaginary Time
Most people know that Albert Einstein was a great physicist. What they do not know is that he was so much more than that. Einstein not only revolutionized physics, but he also helped avert a civil war, was a wise philosopher, offered the presidency of Israel, and, as a young man, had multiple girlfriends. Indeed, most people don’t know that Einstein was in fact more of a god than Jesus Christ. But I digress…
One of the things Einstein discovered is that space and time is essentially the same thing. The phrases “far away” and “long ago” actually have the same meaning in the language of the universe. There is not “space” and “time” in the universe, there is only “spacetime”.
For instance, as I write this, it is Sunday, August 9, 2009, at 1:54 AM, and I am in my basement, typing on my computer. Now, let’s ask an interesting question. Where was I a year ago (August 9, 2008) at this time, 1:54 AM? I was at the University of Delaware Campus, and I was taking Marine Biology Camp. Now for a better question. “What” separates the Brad Rybinski typing this blog from the Brad Rybinski that was at the University of Delaware?
Well, you might say 1 year. But that’s not exactly true. If it were just 1 year, I would have been sitting at my computer on August 9, 2008. So you must also account for distance. The University of Delaware is roughly 20 miles from my house. Therefore, one could say that the Brad Rybinski at Marine Biology camp is one year and 20 miles away from the Brad Rybinski typing this article.
But remember, space and time are actually part of the same thing. So is it possible to calculate how much space time separates the current Brad Rybinski from the one in the past? In other words, can we convert two measurements, the measurement of distance and the measurement of time, into a single measurement of spacetime? We can. The physicist Hermann Minkowski showed how. Lets roll…
1. Everything in science is done in metric. So first, convert 1 year to seconds, and 20 miles to kilometers. 1 year = 31,556,926 seconds 20 miles = 32.18688
2. Take the time difference (31,556,926 seconds) and multiply it by the speed of light (300,000 km/second). This will convert time units to units of distance.
9.4670778 x 10^12 km
3. 3. Square the distance in space. 32.18688^2 = 1035.995244
4. Subtract the number from step 2 from the number in step 3. 9.4670778 x 10^12 km - 1035.995244 = - 9.4670778 x10^12 (My calculator apparently lacks sufficient resolution to get the exact answer, but we can proceed nevertheless.
5. Take the square root. This will produce the distance in spacetime, in kilometers.
(- 9.4670778 x10^12)^(1/2) = (3076861.68) i kilometers
Hmm… So we’ve calculated distance in spacetime, only to get an imaginary number. What does this mean? Math teachers constantly remind students that negative distance has no meaning. So what on earth would imaginary distance mean? I have no idea, and physicists don’t have that many great ideas. The only thing that physicists know for certain is that the presence of i tells us that space and time, though part of the same thing, are still different in some fundamental way; space is still space and time is still time. This obviously agrees with our experience in the world. Oh physics…
Brad Rybinski
Sources:
About Time: Einstein’s Unfinished Revolution by Paul Davies
http://blogs.discovermagazine.com/cosmicvariance/files/2008/11/time-flies-clock-10-11-2006.gif
