Tag Archives: Physics

The Daily Stumble #1: Slow Time

I’m starting a series where I take the 5th Stumble of the day and write a blog post about it. Why the 5th one? I don’t know, why not?

Today’s 5th stumble is: 20 Things that Are Way Better in Slow Motion – [link], from the site BuzzFeed.

Note: I’m going to take a screenshot of every page I stumble for this series, just in case the link breaks in the future. This way, someone reading my blog can still see what I am referring to.

This random stumble is very coincidental, considering my last blog post was about Light in Slow Motion. What are the chances?

Anyways, the site itself has a variety of interesting events happening in slow motion: the popping of popcorn, the impact of a bullet, the lighting of a match, and the hitting of a drum. But the most epic one on this site is definitely the lightning strike:

That just looks insane. When we look at things in slow motion, we see shapes and patterns that are otherwise never observe. We discover physical phenomena that seem impossible to our natural human-time intuition.

At this scale, things happen at time scales so short that that particles zap in and out of existence in billionths of a second. In just a blink of an eye, entire universes of particles have appeared and disappeared, entire realities created and destroyed.

Of course, even one billionth of a second is an eternity compared to events that are predicted to have occurred at the onset of the Big Bang. Such events occurred at 10^-34 of a second, or 0.0000000000000000000000000000000001 second.

It is indeed interesting to watch man-made objects such as bullets and golf balls in slow motion. But it is far more fascinating to watch nature, whether it is lightning, atomic collisions, and even light itself, move in slow time.

The list for The Daily Stumble series is found here.

Light in Slow Motion, and Curiosity’s Descent Video

That is light, recorded at a frame rate so high that a bullet would take a year to cross the screen. It is one of the most amazing videos I have watched this year, perhaps second only to the Curiosity landing video, both of which show that the impossible is always being achieved.

Is Time an Illusion?

[The physics and philosophy article "Is Time an Illusion?" by Craig Callender appears in the June 2010 edition of Scientific American (pp. 58-65). Online article here.]

 

Keith Peters Spacetime
Artwork by Keith Peters, whose illustrations (though not this particular one) appear in the article.

 

Does Time exist, or is Time an illusion? Craig Callender assures us that many physicists believe in the latter and far more bizarre theory. They believe that time is not an intrinsic property of the universe, but rather, an artificial convenience for human beings.

It is a mind-boggling theory. The point is that we can imagine the universe as three dimensions of space and one distinct dimension of time, for a total of four dimensions of spacetime. And our brains have the capacity to handle three dimensions. Normally these are the three dimensions of space, as we leave the effects of the remaining dimension—time—to prediction; that is, if we have one 3D frame, we can predict the next 3D frame in time.

But what if we were to visualize three dimensions again, only this time, we do so for two dimensions of space and one dimensions of time? This 3D frame would tell us exactly what happened in a 2D plane for all time, including the future. This makes much less intuitive sense for a human.

So what evidence do physicists have for casting away time? Here is an excerpt from the article on canonical quantum gravity:

Canonical quantum gravity emerged in the 1950s and 1960s, when physicists rewrote Einstein’s equations for gravity in the same form as the equations for electromagnetism [....] When physicists John Wheeler and Bryce DeWitt attempted this procedure in the late 1960s, they arrived at a very strange result. The equations (dubbed the Wheeler-DeWitt equation) utterly lacked a time variable. The symbol t denoting time had simply vanished.

In other words, time has within this context no intrinsic meaning.

Here is the analogy. Callender compares time to money, saying that it is only a common currency that aimed to simplify a barter system. The article supposes that a cup of coffee is worth $2, a pair of shoes $100, and a used car $2000. Then we can exchange 50 cups of coffee for a pair of shoes, or 1000 cups for a used car.

Then it supposes that light goes 300,000 km per second, the heart has 75 beats per minute, and the Earth has 1 rotation per day. These three processes—the speed of light, a heartbeat, and the Earth’s rotation—can now be described without using time. We may simply start at the base unit of a heartbeat, and say that light travels 240,000 km per beat, while the Earth rotates at 108,000 beats per rotation. A diagram in the print version of the article makes this more clear.

To sum it up: “The concepts of time and change may emerge from a universe that, at root, is utterly static.”

(By the way, according to the article “[the author] assures us that his lifelong interest in time has nothing to do with his last name.” :P)

QED

What’s that?, you say. Why, it’s a theory of physics known as quantum electrodynamics, or in short, QED.

QED

It’s also a book I have read recently. And by recently, I mean today. The book is by Richard Feynman, of course. Its full title is QED: The Strange Theory of Light and Matter. Andrew Widener gave me it as a birthday present, but other than its being a book on physics by Feynman, I didn’t really know what to expect from it. So, I decided to read it. And I found it so compelling that I read it in one day (though it wasn’t really a long book).

Feynman is by no means a modest author. But he has every reason not to be modest. QED is a collection of four lectures for the lay audience and explains a theory—quantum electrodynamics—that is super-accurate, super-applicable, and super-amazing. It doesn’t explain QED mathematically. That is for third-year grad students, he asserts. Instead, Feynman does what he excels at doing—and there are many things in which he excels—serving as an extraordinary popularizer of physics. That isn’t to say that he didn’t actually do physics, for those of you who are unfamiliar with him and haven’t looked him up by this point. He is a Nobel Laureate, which he briefly (and modestly) alludes to in the book when he nonchalantly tosses in a solution to a calculation problem found independently by himself and two others, and he then inserts, in parentheses, “we got prizes for that.”

In this blog post, I’m not sure how to write a response to this book. Should I attempt to summarize what Feynman brilliantly explained, or share personal thoughts? Since Feynman already wrote QED for the nontechnical reader, such as myself, I will focus on the latter idea.

I start by pointing out the obvious, namely, it was no coincidence that Andrew decided to give me this book. I’ve always been a math/science person, whatever that means, and especially into physics. Well, sort of. I would definitely have to explain myself a little more. You see, physics in school—high school, that is—is a rather dull subject. The curriculum is geared towards the memorization of formulas and definitions, the calculation of unknown quantities in perfect, ideal situations, and, dare I say, the performance of superficial experiments whose results we (should) already know, and in which we only try to verify the already-known laws of physics. For me, at least, that contains little fun. On the other hand, the class is great, for we have an awesome teacher with great understanding for both the subject and his students, plus a quirky an interesting sense of humor (see “The Physics Teacher” webcomic). But, as to the subject, I digress.

It seems that we do very little “real science.” We learn in our history classes that the great scientists used imagination, hard work, as well as sheer genius to advance the knowledge and understanding of the day. But in high school physics, there is little room for imagination. Sure, in our homework we might come across a hypothetical projectile motion problem that requires the application of five different kinematic formulas. But is that really physics? Is that how Newton, or Einstein, or Feynman unlocked the laws of Nature?

That objection I have—and no doubt many of you may have—is why I read math/science outside of school for fun. QED was very fun. Feynman presents the concepts of the theory so elegantly that the basics of quantum electrodynamics (what a horrendous name!) are actually by no means difficult to understand. And he didn’t just say, we know this, we know that, here’s a formula, etc. He leads the reader on a journey, a journey of inquiry and discovery. He is patient, not afraid to take time to draw analogies, answer any reader concerns, or qualify his statements. He makes sure to explain precisely what is is known and what is unknown—and how physicists, including himself, are trying to turn that unknown into the known.

Life in the Multiverse

Looking for Life in the Multiverse” is the cover and feature article for the January 2010 Scientific American Magazine [pages 42-49 in print edition]. (The print version of the article contains a number of diagrams, illustrations, and sidebars not present in the above-linked online version.)

I truly enjoyed this article. Alejandro Jenkins and Gilad Perez brought this mind-boggling multiverse hypothesis down to our universe, if you will, and even within Scientific American (I’ve been a subscriber for three years and counting), this article possessed extraordinary insight and clarity. I shall attempt to summarize the article.

You may be familiar with the fine-tuned nature of the universe. If certain fundamental constants, e.g. the relative mass of the proton, were adjusted just slightly, stars would be unable to form and the universe as we know it would fall apart.

However, one revelation of the article is that if two constants are tweaked together, a universe may still be “congenial to life,” or be “compatible with the formation of complex structures and . . . forms of life.” This startled me. It looks like a simple idea once we already figured it out, but the concurrent tweaking of multiple constants is a novelty. It almost seems counterintuitive, as the scientific method normally calls for a control and the tweaking of one variable, or in this case, one constant, at a time. But, our universe becomes merely a soup of particles, so to speak, if only one constant is modified.

Okay, enough abstraction. The article then goes on to give an example—a drastic one—in which the possibility of life is retained. In the example, Perez and his team did not simply adjust a few few constants. They obliterated one of the four fundamental forces of nature: the weak nuclear force.

After tweaking several other constants, Perez’s team found a set of constants that would make the universe congenial to life, even with only three fundamental forces. Still, the “weakless” universe is different. In our universe, four protons can smash together into a nucleus, with two of the protons then decaying via the weak nuclear force into two neutrons, two electrons, and two antineutrinos. In other words, the four protons combine into a helium 4 nucleus. The formation of the helium 4 nucleus is fundamental to nuclear fusion.

In the weakless universe, this specific fusion process cannot occur. A proton cannot decay into a neutron because the weak force does not exist. Hence, stars burn dimmer, producing helium 3 instead, and although helium 4 is still possible to form, it is less common.

Basically, the point is that the weakless universe is capable of forming intelligent life. This revelation has, of course, profound philosophical implications. But I shall omit philosophy here.

A second revelation was found in the realm of quarks. In the “Tinkering with Matter” illustration, several manipulations of quark masses are given, and while some of them lead to congenial universes, others lead to no possibility of a stable carbon-like molecule, a requisite for life as we know.

I just thought this was interesting.