Saturday, September 29, 2012

The Physics Of Fittness - Getting It Not Quite Right

I'm always happy to see when physics is explicitly mentioned as being involved in many of our daily routine. Many of us know this in the back of our heads, but it is always educational when it is mentioned explicitly, especially to laymen, so that they are aware that physics isn't just something one deals in school.

Unfortunately, while the intention is good, the application of various physics principles can often be rather dubious, or filled with errors and misunderstanding. I have been known to nitpick (I fully admit that) stuff like this, not because I like to nitpick, but I think things can be done a lot better and clearer without having to resort to such errors.

This article is one prime example, where they could have gotten it right rather easily, but didn't. I suspect that there is a bit of unclear understanding of simple basic physics here, The writer is trying to point out how the 3 Newton Laws are at work in a fitness routine. Let's go over some of the puzzling aspect of this article.

The first law of motion dictates that an object at rest will stay at rest, and an object in motion will stay in motion. I use this for mental motivation and often say, a person on the couch tends to sit on the couch… but a person who gets up and moves around will keep moving around. An exercise example is the bicep curl. Until your biceps contract to pick up the weight it’s at rest, and gravity constantly tries to pull it back to  rest on the ground.
Right off the bat, the first law is stated in a rather incomplete form. The object will stay at rest, or will remain in motion unless there is a net force acting on that object. This is rather important omission. Furthermore, the object in motion will stay in motion with a constant velocity. The example given in this paragraph of " .... a person who gets up and moves around will keep moving around... " isn't quite accurate because we don't just move in a straight line with constant speed! Not only that, the example given with the bicep curl is a bit confusing. If you stop moving somewhere in the middle of your bicep curl and remain still, you are not doing any work mechanically, but your muscles are certainly doing work and burning calories to maintain that position. The "rest" position isn't just the weight resting on the ground!

Newton's second law of motion states that force equals mass times acceleration. A good example of this when exercising is illustrated when you perform a bench press. The amount of weight you can lift is directly related to the amount of force exerted on the weights by your muscles. Increasing the weight requires more force to lift it. Also, doing reps faster (increasing acceleration) requires more force to be exerted.
This is confusing because of the way it is stated. "The amount of weight you can lift is directly related to the amount of force exerted on the weights by your muscles." What should have been stated here is that the minimum amount of force one must exert to lift the weight must be equal to the weight itself (here, I'm using the term "weight" to mean W = mg, so this is where Newton's 2nd law comes in). The way the statement is stated, it is more related to the 3rd law, which comes next. The last part of the paragraph also has more relevance to the 2nd law than what was stated in the beginning of the paragraph. However, does lifting the weight faster a better way to build muscles? I've read many fitness instructions that insisted that one lift weights slowly and deliberately to really "push" the muscles involved.

When your foot hits the road (or treadmill) you apply a force to the ground, which responds with an equal and opposite force, helping to propel you forward. As you speed up, either the length of your stride or how frequently your foot hits the ground increases. Working to improve your running stride can help make every run feel less taxing, increasing both the speed and distance you can cover.
Again, this illustration of Newton's 3rd law is confusing. What propels you forward is friction, not the equal and opposite force that is the result of the force you apply to the ground. The equal and opposite force here means that you don't crash through the road or your treadmill. Rather, this is where the weight lifting example in the previous paragraph would have been more relevant.

The writer than has more confusing article on other issues of biomechanics.

The biomechanics of stability, the less an object’s surface area touches a solid base, the less stable that object is. Applying this basic principle into exercises makes our whole body work harder, meaning a higher calorie burn, plus a more challenged core.

Now, by bringing your hands closer together during the pushups, or your feet closer during squats, you have not changed the surface area between you, and the object in question (the ground), has it? After all, the contact surface area (your hands, or your feet) has not changed. Only the separation between your hands or your feet is the one that has changed. So the principle involved does not match the example. I'm not saying that the stability hasn't changed in those cases, but the reason why one scenario is more stable than the other doesn't match the explanation or principle given.

The lack of the subtle understanding of these basic physics concepts is what separates between a superficial knowledge of physics versus a deeper understanding of it. We hope that students that have gone through at least an undergraduate/intro level physics classes in college can acquire the latter and spot the differences in such subtle understanding.


Thursday, September 27, 2012

"String theory: big problem for small size"

This paper is an "intro" to String Theory. Well, at least that's what the paper claims.

Now, don't think you actually will learn much from it, because String Theory is highly mathematical, and this paper doesn't even present much, if any, of the theory. All it does is present a superficial argument for String Theory. So in that sense, this is as good of an intro to laymen as any. You'll get some general idea on what String theory is, but nothing substantial beyond that. I won't be surprised if, after reading this, you end up with more questions than you started with.


Wednesday, September 26, 2012

More Evidence On Majorana Fermions

On the heels of the possible discovery of Majorana fermions earlier this year, along comes more evidence of their discovery, and this time, they came from a Josephson experiment.


There ya go! So far, in the race to detect the existence of the Majorana particles, it is two for condensed matter physics, and zero for high energy physics.


Monday, September 24, 2012

The Chemistry Of Cleaning

Yes, cleaning! Enough with the Higgs, and the Dark Energy, and the pnictide superconductivity. Let's get dirty and learn about the physics and chemistry of cleaning!

This brief overview actually came from a janitorial service company, but it has a nice article on the chemistry of cleaning, with lots of external links if people care to read more. It's one of those things that we use and encounter each day, but for many of us, we don't give a second thought on how or why it works. So wash your hands (with soap), sit down, and learn what you just did.


Saturday, September 22, 2012


Answer: around 275.





Friday, September 21, 2012

Nobel Prize For The Higgs? Maybe Not This Year






Thursday, September 20, 2012

Will Biology, Astronomy, And Physics Rule Out God?

More arguments on this very topic, and this appears to be a continuation of what Sean Carroll had stated earlier. So I'll let you read the article for yourself.

The one part that I think worth highlighting is towards the end:

And I think, this is where a lot of the misunderstanding between both sides of the fence occurs. Those outside of science (theologians) appears to not realize that to counter a scientific argument, one must use another scientific argument. Simply arguing that such-and-such must surely point to the existence of "god", without offering evidence (rather than not being able to falsify it) simply isn't convincing, nor can it be used as an evidence. The "god of the gaps" should no longer be used at this point, because history has shown that these gaps continue to diminish over time!

Certainly a thought-provoking article.


Tuesday, September 18, 2012

Paper or Electronic?






NOVA's "Making Stuff: Stronger"




Monday, September 17, 2012

How to Measure the Width of a Hair With a Laser!

Those folks at JLab are at it again. This time, they use a simple laser pointer to measure the width of a hair.

This is a fun project and suitable for high school classes.


Monday, September 10, 2012


I'm on vacation. I hope nothing important happens while I'm gone. :)


Wednesday, September 05, 2012


Continuing with my survey of the physics jobs advertisements in Physics Today, here are the statistics that includes the Aug 2012 issue.

1. Number of jobs looking only for experimentalist = 43
2. Number of jobs looking only for theorist = 14
3. Number of jobs looking for either or both =31



Tuesday, September 04, 2012

Theoretical Physics is NOT Always Esoteric!

This is another example where people think "theoretical physics" deals only in some esoteric, non-applicable physics such as elementary particles, high energy physics, etc.. etc. And unfortunately, people that were interviewed in this article didn't help much to kill the misconception!

"We're not going to see dark matter in Starbucks anytime soon," laughs Tim Meyer, head of Strategic Planning & Communications, adding it's okay to wonder if theoretical physics has practical uses.

Oy vey.

I've already made my reply to correct this misconception in another blog entry on people wanting to do "theoretical physics" but not realizing that that statement actually is rather vague. I think physicists should be quick to correct such misconception, because not only does it harm our field (i.e. a lot of theoretical physics HAVE direct implications to our everyday lives, AND have direct uses!), it also insults many theorists who are working on areas that have practical applications, which, the last time I checked, outnumbered those working in the esoteric fields.

We can correct things a little at a time, which is why we shouldn't miss such opportunities when they appear.


Saturday, September 01, 2012

A Tale Of 3 Photons

Not exactly similar to the 3 Wise Men, but these 3 photons could cause serious implications for many theoretical models that attempt to merge gravity and quantum field together.

Supposedly, the 3 gamma photons came from a gamma-ray burst, and were detected by the Fermi telescope within a millisecond of each other after traveling all that distance. The implication here is that if space isn't smooth, but rather quantized at the Planck scale, this "foam" would have affected how quickly photons can travel over some distance, and will be more apparent as the distance goes larger. The closeness of the time of arrival for these 3 photons appears to set the graininess of space, if any, at a scale lower than the Planck scale, which would ruffle the feathers of a lot of theorists.




Many things — e.g. stars, interstellar dust — could have dispersed the photons. "But nothing that we know can undisperse gamma-ray photons," Nemiroff said. "So we then conclude that these photons were not dispersed. So if they were not dispersed, then the universe left them alone. So if the universe was made of Planck-scale quantum foam, according to some theories, it would not have left these photons alone. So those types of Planck-scale quantum foams don't exist."
Oh, here's the reference to the PRL paper:

R.J. Nemiroff et al., Phys. Rev. Lett. 108, 231103 (2012).

Now, I could have sworn that a while back, I read a theoretical paper somewhere which indicated that photons traveling through such quantum foam may not show any change in travel time. Since the slowing down and speeding up over a Planck scale is random, after a while, the randomness washes out and the speed remains the same over very large distances. I can't seem to find that paper right now, but essentially, the result reported in this observation doesn't really rule out the existence of such quantum foam.... at least, not yet anyway.