Friday, June 24, 2005

Think Like Einstein

Just want to make my blog a little more fun for the visitors. I found some simple and interesting questions from NOVA Online which I think can help readers who have no knowledge in time travel to understand quickly. Trust me, the 4 questions will make you think like Einstein, don’t worry as they are not hard at all, really! You can post your answers in the comments if you are interested in knowing the answers.

1. Adding velocities
You're on a train that's moving forward at 50 mph. You throw a ball in the direction that the train is moving. Relative to you and the train, the ball leaves your hand travelling at 20 mph.

Question: From the point of view of someone standing alongside the tracks, how fast is the ball moving?

2. Speed of Light
OK. Everything so far makes sense. Let's move on to the speed of light for a moment.

Again, you're on a train. This time, though, the train is moving much faster—at half the speed of light, or 93,000 mps (miles per second). And instead of throwing a ball, you turn on a flashlight.

Question: How fast is the light travelling relative to the observer standing alongside the tracks?

3. The Speed of Light
Here's our last question. This one's like the previous one, but with a twist. Again, you're on a train moving at 93,000 mps, and again, you turn on your flashlight.

Question: How fast does the light travel relative to you?

*You should have realised a paradox in this question, otherwise you shouldn’t move on to question 4.

4. The Solution
By now you probably understand the conflict: How is it possible that light always travels at the same speed, no matter how fast its source is moving? Einstein, when he was 16, thought about the same thing.

Are you familiar with the equation v=d/t? All it says is velocity (speed) equals distance travelled divided by time.

If we use this equation in our first scenario—the one where you threw the ball—it works out fine. For you, within the train, as well as for someone standing by the tracks, we can calculate the speed of the ball by adding the distance the train travelled and the distance the ball travelled.

The equation does not work out so well in the second scenario, though, because we're dealing with the speed of light, so the "v" in the equation always has to be 186,000 miles per second.

Something has to give.

Question: What can we infer from what we've seen so far?


Sunday, June 19, 2005

Latest News On Time Travel!

I have been fascinated by time travel since I was a little kid but I just started to understand time travel a little bit more when I was learning Relativity and Quantum Physics. Einstein discovered that time travel is possible in his Theory of Relativity many decades ago. I would like to talk about the latest findings done by the physicists today in this post. I just got to know three latest findings, two are for wormholes and another one explained the paradox of time travel.

For a long time, wormholes are the theoretical tunnels which seemed the best way for us to do time traveling. Using wormholes to do time traveling can be seen in this way. Mark 2 holes at the opposite ends of a paper to represent 2 points in space-time. Then the paper can be bent so that 2 points are on placed top of each other. In this way, a person can theoretically go through a wormhole and appear at another space-time. The region that a time traveler will pass through called the throat, exotic matter is used to fill the throat to keep the wormhole open.

Calculations by Stephen Hsu and Roman Buniy of the University of Oregon show that a wormhole combining exotic matter with semi-classical space-time would be fundamentally unstable.

“We aren’t saying you can’t build a wormhole. But the ones you would like to build – the predictable ones where you can say Mr Spock will land in New York at 2pm on this day – those look like they will fall apart.” Dr. Hsu said.

A different approach to the question of wormholes was done by Chris Fewter of the University of York and Thomas Roman of Central Connecticut State University. Their calculations show that, even it is possible to build a wormhole, the throat would be too small for time travel.

“It might - in theory - be possible to carefully fine-tune the geometry of the wormhole so that the wormhole throat became big enough for a person to fit through. But building a wormhole with a throat radius big enough to just fit a proton would require fine-tuning to within one part in 10 to the power of 30. A human-sized wormhole would require fine-tuning to within one part in 10 to the power of 60. Frankly no engineer is going to be able to do that” Says Fewter.

According to Einstein, space-time can curve back and allowing us to travel to the past. Time travel to the past is thought to be possible by physicists and nevertheless it gives some uncomfortable contradictions. The obvious one would be that theoretically, we can travel back in time and do something which will change the present. This is something I always wanted to do when I was a kid although I didn’t think about the consequences of it. If you think more, it will eventually mess up the whole theory of time travel.

Today, a team of physicists from US and Austria says that it is possible if only there are physical constraints acting to prevent the present from changes in the past. This new model uses the laws of quantum mechanics to get rid of the paradox. The physical constraints exist because of the laws of quantum mechanics although they don’t account for backwards movement of time before. This model is easy to understand as quantum behaviour is governed by probabilities. There are a numbers of possibilities regarding its state before something is observed. But the possibilities will shrink to 1 when the state is measured, which means the uncertainty is eliminated.

"Quantum mechanics distinguishes between something that might happen and something that did happen," Professor Dan Greenberger, of the City University of New York, US.


Tuesday, June 07, 2005

The Other Milesian

You maybe wondering who is the other Milesian. Well its me. My name is Ruben, and it was my friend Choy's idea to start this blog after we overheard two of our esteemed colleagues trying (quite unsuccessfully) to disprove the theory of evolution. This blog will contain all our interests and philosophisings. Since we are thinkers, we decided it is better to put down and share our thoughts somewhere instead of letting them fade away into nothingness.

I too remember that day when our colleague said that if you shake a rock long enough, nothing will happen. I think I know what he meant. Maybe he meant that in order for anything to change so drastically until it becomes another thing entirely, a superior being like God has to intervene. This kind of thinking should be classified as pure laziness. If someone cannot explain or understand how the many forms and variations of life came about, he just says, "God's work" and leaves it as that. He is too lazy to think of a proper explanation and try to understand the universe better. The theory of evolution may be just a theory, but its definitely far better and more solid than saying God made it happen. And besides, the Uncertainty Principle proves that all the air in a room can exist at only one corner in that room if given a long enough time. So if my esteemed colleague were to shake his rock long enough, all the matter in that rock will exist, for a fleeting moment, in just one part of the rock's volume.

So come back here in the future for more interesting articles on this universe and everything within it.


Monday, June 06, 2005

A Pathetic Creature's View Of It's Universe

Our human experiences tell us that we seem to live in a 3 spatial dimensions universe. But some physics theories include additional spatial dimensions. Not only that, some experiments also showed that we are in fact living in a higher physical dimensions universe than we think. I have been wondering how does a high dimensional world look like for a long time but I just couldn't imagine. I always like to think myself as a pathetic creature in a curved flatland who tries to figure out how does a 3D universe looks like while other 3D creatures laugh at my foolishness. Maybe I will never ever know how does a high spatial dimensions universe looks like but I think I do have some clues about it. This idea comes from imagining myself as a flatland creature.

We all should know the shadow of a 3 spatial dimensions object on a flatland (who doesn't know...) for which we can think as a cube's shadow on a paper where the paper has length and width but NO thickness at all. Hence, the same way, I think we can imagine the shadow of a 4 spatial dimensions object in a 3 spatial dimensions universe. I have sketched them out in the picture below.

That is only the shadow of a 4 spatial dimensions object, Mathematics favor String theories with 10, 11 and 26 physical dimensions! I really hope I will have the chance to see someone shows an equation explaining the universe we are living, no matter a simple or a complex equation.