Time Travelers, Please Proceed to Gate Number 42

Last night while watching Hiro Nakamura and Nathan Petrelli doing their thing on Heroes, I came to the conclusion that strolling through the forth dimension is much more fun than flying through the other three. While time traveling seems like a great way to spend your weekends, is it feasible?

Forward time traveling is relatively simple. It can be achieved by accelerating to extremely high speed or by getting close to an extremely big mass. As predicted by Einstein’s theory of relativity - time is subjective. For example, you can go on a one minute high speed trip only to return to Earth to discover you have just missed a whole decade back at home. A real-life example is the cosmonaut Sergei Avdeyev that spent a total of 748 days on the Russian space station Mir and missed a whole 0.02 seconds on Earth.

Although that DeLorean looked really cool on Marty McFly, backward time traveling may be theoretically or practically impossible. Some claim it can be done using wormholes, black holes or other abnormalities of spacetime, while others claim it exists only in science fiction.

If backward time traveling is possible, where are all the tourists from the future? Even if it will be illegal in the future to go back to the past, I’m sure some would break the law eventually.
Possible explanations are:
1. Backward time travel is not possible.
2. It’s theoretically possible but practically impossible.
3. It can be done, but we will destroy ourselves before achieving this.
4. It will be done in the future, but time machines allow you only to go back as far as the time the machine was created.

A famous problem is the grandfather paradox, where a man travels back in time and kills his own grandfather before the latter met the traveler's grandmother. As a result of this act, the traveler could not have been born, so how can he later travel back in time? Some see this paradox as a death blow to backward time travel possibility, but although definitely weird, I think the only problem here is that it’s not aligned with our intuition. Because human logic was developed by evolutionary process in order to better hide from lions and hunt zebras more effectively, I don’t see a big problem in the fact that 21st century thought experiments regarding traveling through the forth dimension don’t appear logical to us hunter-gatherers.

No need to comment on this post since I have just been back from the future and already read all your comments.

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p.s. Every time a lightning hits the Eiffel Tower there’s a 78% chance your wife’s on the phone.

Relatively Useful Relativity Tips (for you and your relatives)

You know what’s my problem with Einstein’s theory of relativity? Not that it’s inaccurate (like I would know) or inelegant (like I would care), but that it’s god damn useless. OK, sorry, I admit it, there are about ten guys from NASA that must use the Lorentz factor every once in a while, but what about the rest of us 6,599,999,990? Are we not worthy of enjoying uncle Albert’s heritage? I say no more! This ends now! I give you… drum rolls… (snare drum X 16, bass drum, crash cymbal). My tip list!

Tip #1: Make a very fast drive-by-style pass with your car if you wanna catch David Blaine slipping a card up his sleeve. Time on another reference frame (David Blain) will always look slower, depending on the relative speeds between the two frames (Blain and you). This phenomenon is called Time Dilation. Note that you may need to sell your Toyota and buy a faster car. For example, you’ll need to travel at 86.6% of the speed of light in order to delay time by half. So, this tip (as all the others), is theoretically true and magnificently useless.

Tip #2: Accelerating and decelerating your car may be bad for the brake system and fuel consumption, but it will make you look younger. Well, at least younger than everybody else your age. The acceleration will cause your time (everything - your wristwatch, your heart rate, your metabolism…) to move slower than the regular time on the ground. Note that you will not feel like you are living in slow motion (but will probably feel like you wanna puke from all the accelerations and decelerations).

Tip #3: The Twin Paradox. If you’re considering start dating one of the Olsen twins and wonder how she’ll look when she’s old, take her with you on a fast shuttle ride to Alpha Centauri. When you are both back on Earth, look at her sister. If you’re not happy with how her sister looks (this is how your date will look in a few years), take them both to another fast shuttle ride to Alpha Centauri, and just leave them there.

Tip #4: Objects can not travel faster than the speed of light, but allowed to move at any speed below that value. Use this when your kid tells you he came as soon as you called him.

Tip #5: Two events happening in two different locations that occur simultaneously to one observer may occur at different times to another observer. Watching your daughter on her synchronized swimming lesson from a moving airplane can make you wonder where your money went.

Tip #6: Lorentz contraction. Objects appear shorter from another relative speed reference frame. If you wanna be a porn star, don’t move while you’re auditioning.

Tip #7: The lower you go, the stronger the G-force, and gravity slows down time. Choose a low chair for long boring office meetings. To you, they will appear shorter.

Tip #8: Equivalence of mass and energy. If you’re making a home-made super bomb and C4 is hard to get, try using ultra-fat people.

Tip #9: A black hole is an object with gravitational field so powerful that even light cannot escape its pull. Sounds too good to be true, but placing your mother-in-law behind an event horizon might actually work.

Tip #10: As an object's velocity increases, its mass appears to increase. If your wife’s on a moving spaceship, shouting at you “Is this dress making me look fat?” - screw the physics, shout back “No dear, you look exactly like you did on the day we first met!” (to be honest, although her mass will increase, her waistline will shrink due to the Lorentz contraction effect, so she will actually look thinner, but that will kill my joke).

So, there you have it. As promised… theoretically true and magnificently useless. Oops, my bad, sorry again, you ten guys from NASA can still use this list when appropriate, okay?

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p.s. Remember your mistakes so the next time you’ll know you made them all over again. (credit not mine)

Land Ahoy! - Navigation at Sea in the Age of Sail

A few days ago, a friend of mine told me he’s thinking about buying a boat and learning how to sail it himself. He told me nowadays everybody keep sight of land at all times and just sail parallel to the shore, so it should be a piece of cake. When I asked him if he’ll be brave enough to go on a sea-crossing voyage without a GPS, he just smiled. That reminded me of the famous longitude problem.

In the 17th and 18th centuries, ships were crossing the vast oceans on regular bases, but often these journeys resulted in shipwrecks and loss of lives due to miscalculating the ship’s current location. Dead reckoning may be a good solution for short distances, but for long distances you need a way to know exactly where you are (within an acceptable margin of error). Although the ship’s current latitude had been relatively easy to find by reading the angle of a sextant aimed at the sun at its highest position in the sky, finding the ship’s longitude had been a much harder task. This problem was known as ‘The Longitude Problem’, and it was once though to be beyond human capabilities. Since the Board of Longitude has offered a large sum of money as a prize to the one who will solve the longitude problem, many had tried. But throughout the years, although many crazy solutions had been suggested, there had been only two that seemed at least partially sane.

The most popular proposition to solving this problem was known as ‘The Lunar Distance Method’. It was claimed that by creating extremely detailed tables of positions of the moon and the stars, it will be possible to calculate your exact longitude. Although using celestial bodies was a possible solution in theory, in practice, it produced errors of hundreds of miles, and therefore – useless to sailors.

Its rival proposition was to have a precise chronometer on board the ship. In theory, if you had a precise clock set to your home port local time, you could know your own longitude. For example, if the clock points to 1 PM when the sun is in its highest position in the sky, it means you are fifteen degrees west of your home port. The problem was to produce this extremely precise clock that will keep being reasonably accurate for long period of time while facing corrosion in salt air, wide variations in temperature and humidity, odd angles, and constant movement. Although thought to be an impossible task, one man, an English clockmaker named John Harrison, had managed to manufacture such a clock after years of relentless work (eventually reaching only two miles of error on a cross-Atlantic voyage). Not before a struggle had the Board of Longitude acknowledged Harrison’s solution and granted him his hard earned prize. The longitude problem was finally solved.

A modern GPS device relies on trilateration with satellites, using an accurate internal clock to measure its distance from these man-made artificial celestial bodies. I think it’s beautifully ironic that the modern solution to the exact location problem is some kind of a mixture between these two rival methods.

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p.s. If the Coriolis effect really affected draining sinks, plumbing was a big issue in Kenya.

1, 2, 3, God, 5, 6 - Why Do Clocks Use IIII Instead of IV?

Have you ever wondered why almost every modern clock or watch with Roman numerals uses ‘IIII’ instead of ‘IV’ to represent 4 o’clock? There are several possible explanations.

One likely explanation is that the strict use of IV instead of IIII wasn't common until after the Middle Ages. Clocks and watches are patterned after sundials, which were in use long before the Middle Ages.

Another likely explanation is that using IIII brings more symmetry and balance to the dial. The four-character form IIII is "heavier" than the IV and creates a visual symmetry with the "heavy" VIII on the other side. Another symmetry is achived because the I symbol would be the only symbol in the first 4 hours of the clock, the V symbol would only appear in the next 4 hours, and the X symbol only in the last 4 hours.

A practical reason can be that IV is difficult to read upside down and on an angle, particularly at that location on the clock (can be confused with VI).

Another reason is related to the molds used to cast the metal numbers. Using four I's instead of one I and one V will total in 20 I's, 4 V's, and 4 X's per one clock, so all the numbers could have been manufactured using one mold of 'I I I I I V X' four times.

There are some stories of several kings objecting to the IV form, but these seems unlikely.

But the most surprising explanation I’ve found would have to be this: In ancient Latin, ‘I’ was used instead of a ‘J’, and ‘V’ instead of a ‘U’. So ‘IV’ was an abbreviation for the Roman god Jupiter (IVPPITER) and using IV could have been considered sacrilegious. I guess the Romans thought 1, 2, 3, God, 5, 6… looks too weird on a sundial.

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p.s. Bringing your pet elephant to work is a bad idea, even if it is Casual Friday.