From the Greek meaning 'heavy with wine'
A blog devoted to science and reason
Written after a glass or two of Pinot Noir.

Saturday, August 16, 2014

The Impossible Is Still Impossible

I saw this article in Wired referenced on a couple of science pages on FaceBook. 

NASA validates 'impossible' space drive

Let me give you the short version of how this engine is supposed to work. Microwaves are beamed into a cone-shaped cavity. They bounce around the cavity and produce a force on the cavity in a direction perpendicular to the direction they were beamed in. Imagine  turning on the microwave oven and watching it push itself off the kitchen counter.

Why is it impossible? This violates one of the basic laws of physics. 

The Conservation of Momentum

The conservation of momentum isn’t your ordinary law of physics. It is one of the most fundamental principles in science. It is intimately related to spatial symmetry. Roughly speaking, the laws of physics here are the same there. You may know this as Newton’s third law of motion or for every action, there’s an equal but opposite reaction.

To obey the conservation of momentum, propellent is pushed out by the rocket and the rocket is pushed by the propellent. This engine is said to produce thrust without any propellent. 

So I was immediately skeptical. So I dug around a little bit. I found a short description of the experiment. One thing I found interesting is that the authors did not lecture on “”physics of the quantum vacuum plasma thruster.” All right, that’s fine; if the results were groundbreaking, the explanation might come later. Something similar happened in 1986. Researchers at IBM discovered ceramic materials that lost all electrical resistance (superconductivity) at surprisingly high temperatures. There is still no complete explanation for why this happens. What is different about these two cases is that the superconductivity ceramics didn’t violate any basic principles of physics.

What made me laugh however is the authors claim that their device may be “demonstrating an interaction with the quantum vacuum virtual plasma.” I have no idea what they mean by a quantum vacuum virtual plasma. 

I also found their paper. This made me giggle, too. They built two devices: one was designed to work, the other was designed not to work. Both versions produced the same amounts of thrust.

Phil Plait in his Bad Astronomy blog at Slate says this episode is reminiscent of the faster than light neutrinos and the mysterious force slowing down the Pioneer spacecrafts.

It reminded me of an article that caught my attention while I was in grad school. I remember getting all excited about this revolutionary paper published in one of the premier physics journals. The authors had data that showed that a gyroscope rotating in one direction weighed less than if it were rotating in the opposite direction. Finally, an anti-gravity device!

My research advisor wasn’t nearly as excited. His comment was something along the lines of “systematic error.” But still I held out hope.

Then four months later, my anti-gravity hope were dashed. Others trying to replicate the results found there is no anti-gravity.

Sunday, August 10, 2014

KCAL 9 And The Supermoon

I was watching the KCAL 9 news at 10 p.m. They had a report on the super moon. (yawn)

But then Serene Branson said this:
And they say that with the full moon like that, that if you’re feeling a little tired, a little sluggish, that it’s because of the pull. Just like how the moon has an effect on the tides, it has an effect on us, because we’re mostly water. And that’s when the crazies come out.

Despite what Bill O’Reilly thinks, the tides have a well-known cause. The tides are due to the difference in the strength of the gravitational force on opposite sides of the earth. 

There is no measurable effect on the moon’s gravitational field on us. UCLA astronomer George Abell calculated that a mosquito on your arm would exert a greater gravitational force on you than the moon.

As to the supposed lunar lunacy, that too was debunked long ago

I thought that maybe KCAL meteorologist Amber Lee might correct her, but no. That got me to thinking about Lee’s credentials. She has a bachelor’s degree in communications and a master’s in journalism. No degree but a certificate in  meteorology through Mississippi State University’s Broadcast Meteorology Program. To earn this certificate, she had to pass an online exam consisting of 100 multiple choice questions. 

Thursday, July 24, 2014

Chuck Norris Doesn’t Need Facts

Last week, Chuck Norris in his column at the World Net Daily* claimed that the rise of allergies is linked to the use of vaccines. He even quoted physiologist, Dr. Charles Richet who won the Nobel Prize in Physiology and Medicine for his ground breaking research on allergies (anaphylaxis).

Only problem is that Dr. Richet’s work took place at the turn of the 20th century. He won his Nobel Prize in 1913. 

Does that mean Chuck couldn’t find any scientific research done on allergies or vaccines in the last 101 years?

Or did he conveniently ignore it?
*Sometimes this publication's title is misspelled as the World Nut Daily.

Wednesday, July 2, 2014

When I Say Something Stupid

Last night during class, I asked the students to imagine explaining something to their mothers. One student immediately asked, “Why mothers? Is there something special about mothers.”

Oops. So I quickly changed my statement. I said imagine explaining this to your parents. She shot back. “Isn’t that ageist.”  I was caught again. I love students with sharp minds.

Some of you readers might think this is about political correctness, but you would be wrong.

My Mother
My mother comment can probably be traced back to some advice I got when I was preparing one of my first presentations as a graduate student. I was told that I should make it understandable to a general audience and that a good rule to follow is to imagine giving it to my mother. 

Why my mother? I don’t know, but physics was mostly men when my advisors were in school, it was was mostly men when I was in school, and it is still mostly men now. That fact probably has much to do with it.

The term for this sort of thing nowadays is mansplaining, and it is hardly unique to physicists. Plus mansplaining, I think, can occur whenever one person regardless of gender assumes that another lacks knowledge of a subject because of some unrelated factor like gender or age.

I’ve said other stupid things in class, like the time I told a class that I was going to give them a softball question. A woman in class asked what that was. Now I don’t know if she truly didn’t know or was politely pointing out that I just said something stupid. 

I played some softball in grad school. There was this informal league of grad students from various departments. There were men and women of all sorts of athletic ability. The pitcher threw slowly and every effort was made to ensure that people hit the ball. Plus lots of beer was drunk. Lots and lots. Some of us would even run the bases with a cup in our hand trying very hard not to spill any.

That’s my idea of softball, so a softball question is just one that’s easy to answer.

But when she asked what a softball question was, the first image that came to mind was women’s softball, and if you’ve ever have seen a softball game, you know that there’s nothing soft about it.

I like the fact that I’m still capable of learning.

Thursday, March 27, 2014

To Brian DeFacio

All of the professors in the physics department at the University of Missouri had a substantial impact on who and what I am. Three, however, deserve special mention, because they had an outsized influence on me both as the physicist and teacher that I am.

David Cowan, my research advisor, taught me to see science as one big picture. Henry White demonstrated much confidence and a lot of patience in a graduate student and allowed me to be one of the first two graduate students to teach an undergraduate course.

Brian DeFacio. I could always count on him for a conversation. In my acknowledgment section of my dissertation, I included a joke that that only those who knew Brian will get. 
I thank Dr. Brian DeFacio for innumerable conversations.
These never occurred in his office. Sometimes in the hallway, sometimes before or after class, but usually in the physics department lounge. Breaking news in physics? Brian would be all too happy to discuss it with you. An interesting problem in a course? He wouldn’t necessarily help you with it, but he would put his own special spin on it. 

Sometimes he would relate personal stories. A favorite - Brian was serving in the armed forces, Army I think, and stationed at a Nike missile facility. There was this young lieutenant who didn’t think too highly of Brian and often pulled rank. Brian was on guard duty one night when this officer came by his post. Brian challenged him, and the officer did not respond with the correct counter phrase. He then ordered the officer onto the ground and held him at gun point until others arrived.

What you should take from this story is how he treated people. Brian always treated us grad students as colleagues. He never used his position as anything other than teacher, mentor, and friend.

In the classroom, he was a wonder. No one could fill a blackboard like him. Room 305 held at most eighteen people, and it had boards on three walls. Brian would start at the front on the left, and after half an hour would reach his starting point, and we would then start the next lap. I remember inventing a DeFacio dictionary that I kept in my head. Note taking because much easier. So when I wrote “linear, isotropic, and homogeneous,” I just thought something like “the usual case.”

One day, halfway through the lecture, someone caught a sign error. After correcting it, he told my favorite story of one night while working at home, his wife asked him if something was wrong. Brian said that he was trying to find a missing minus sign. She asked him why don’t you ever try to find a missing plus sign.

Brian also had a way of making you come up to his standards. I was in his Condensed Matter I course. We had two homework assignments and a final exam. I didn’t do every well on the first homework set, but I did all right on the second. I missed one class that semester. He saw me the next day and said I had missed the best lecture he ever gave, one on Anderson localization.

When the final came along, there were two facts of life. Because I did poorly on the first homework, I had to do well, and I had to know Anderson localization. I nailed that test. Perfect answer on Anderson localization. After checking with some classmates, I suspected I had the highest score on the final. So I was a little miffed when Brian gave me a B, but that lasted about 30 seconds, because he was right. I blew off the first assignment; he knew it, and I knew it. He wanted us to do the best we could at all times.

Toward the end of my comprehensive exam, Brian raised his hand to ask a question. Now I was prepared for this exam. I knew my research topic. I could have answered nearly anything the committee could throw at me. So what did he ask? 
Calculate the power output of a fly.
I haven’t seen or spoken to Brian in twenty years. Now there are no more opportunities for discussions, but in a way, that’s okay, because of all those conversations that were too many to count.

Monday, December 23, 2013

Grandma Got Run Over By A Reindeer

Remember this Christmas song?
Grandma got run over by a reindeer
Walking home from our house Christmas eve
You can say there's no such thing as Santa
But as for me and Grandpa, we believe 
She'd been drinkin' too much egg nog
And we'd begged her not to go
But she'd left her medication
So she stumbled out the door into the snow 
When they found her Christmas mornin'
At the scene of the attack
There were hoof prints on her forehead
And incriminatin' Claus marks on her back

So I got to thinking. What would happen in a collision between a reindeer and an elderly woman.

While the song seems to imply that Grandma may have already been lying drunk in the snow and was then trampled by the reindeer, I’ll assume a more violent interaction. She was walking, and the reindeer, running down the road, hit her from behind.
Typical Diagram Drawn by a Physicist
The physics here involves the conservation of momentum. To simplify the problem, I’ll assume that the collision is like the one between billiard balls, what a physicist calls an elastic collision.

Momentum is the product of an object’s mass and its velocity.
A fundamental principle of the universe is that momentum is conserved; that is, this quantity of motion doesn’t change. It is mathematically expressed like this.
In collisions like ones with billiard balls, the total kinetic energy also is constant.
Let’s suppose this reindeer weighs 400 lbs. and was running at a speed of 45 mph. Let’s also suppose Grandma weighs 110 pounds and was walking at 4 mph.

With a bit of algebra we can find what happens to Grandma. It ain’t pretty. Grandma flies forward with a speed of almost 70 mph.
CREDIT: coolthings
Now about this family that let’s an old woman drink too much and then let’s her trudge all alone through the snow. 

Sunday, October 27, 2013

What Does a Physics Degree Get You?

Free food.

I woke up yesterday, and as I do everyday, I checked my email. There I saw that I had been tagged on FaceBook by Steve, a relative of mine. He posted the following:
Need some help from my academia family and friends! I need to present "in layman terms" how cold it would have to be outside to freeze 2 gallons of water @ -19ºC. 
Background: The product I sell has a moisture cured urethane in it and is activated by water. I am working in Canada where the lowest ever temp recorded was -60ºC (1947) so how long would it take to freeze a 2 gallon sprayer of room temp water which is about 10ºC at -19ºC. 
1st person that can explain it (so my block head can understand it) win's a perfectly smoked brisket delivered or shipped to "His or Her" home!!
Now he posted this at 5 am (7am Texas time), and I was still blissfully asleep. One and a half hours later, he wrote
So far my simple question is still unanswered! (Tick Tock) BTW when the west coast awakens my family physicist Vann Priest will have no problem with this so you all had better hurry!!
By the time I awoke at 8:30, Steve had already gotten some really good answers from Brian and Karen, so I was afraid I lost a chance at some Texas smoked brisket. I should make clear that Steve has this awful habit of posting his BBQ on FaceBook, and whenever he does, I drool all over my shirt. However, since he didn’t yet award it officially, I figured I might still have a chance.

A brief shout-out to Kevin who is quite an accomplished smoker. Kevin's brisket is also scrumdiddlyumptious, and I have been privileged to taste it on several occasions. It might be awhile before Kevin or I get another brisket though. He just became the father of twin boys.

So here’s my answer.

First the water has to cool to 0ºC. Newton’s law of cooling states that the rate at which the temperature of an object changes is proportional to the difference in temperature between the object and the environment. Fancy way of saying that if you want to cool something off really quickly, you put it in the refrigerator; if not, leave it in the kitchen.

Mathematically, Newton’s law is written

T is the temperature, t is time, TE is the temperature of the environment, and k is some constant. This is a straightforward first order differential equation.  The solution is

The problem though is that to find the time t we need to know both constants, k and C. There’s a lot of complicated physics that goes into k and C; however, to find C, we can set the time equal to zero. We know the initial temperature of the water and the environmental temperature. Punching a few numbers into my handy calculator gives me 3.37. We could do something similar to find k, but we would need to know the temperature of the water sometime later. I don’t have that information, so I can’t find the time it takes to cool down to freezing.

I’m not going to let that stop the analysis though. Once the water reaches 0ºC, it begins to turn into ice. The temperature stays at zero until all the water freezes. We can find how long it takes by knowing that the energy transfer happens by thermal conduction. Here’s the equation governing this phenomenon.

Q is the amount of energy that is being transferred (usually called heat), t is again the time, T is the temperature of the object through which the energy is being transferred, and x refers to the thickness of the object. There are two constants here too. A is the cross-sectional area of the object, and k (a different k) is called the thermal conductivity. (Once again, a lot of complicated physics rolled into a single number).

Here is a major complication. I can look up the thermal conductivity and figure out the area and the thickness.  The total amount of energy transferred in so problem; Q = mL where m is the mass of the water and L is the amount of energy required to change the state of the water per kilogram. But this differential equation is for one dimension only.  To do it in all three directions is some tough mathematics.

There’s no easy way to solve Steve’s problem.

Or is there?

I’m an experimental physicist. Let’s do the experiment. The freezer in most refrigerators is about -19ºC. Let’s put one gallon of water in the freezer and see how long it takes. The time it takes for 2 gal will be about twice as long.

Two hours into the experiment and the first thin layer of ice begins to form. In another hour, there’s a significant amount of ice. So Steve has about four hours before he needs to worry, and a Texas smoked brisket is on its way to California.