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!!

CREDIT: Steve

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.

CREDIT: Steve

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.

Wingnut Thermodynamics

Bryan Fischer, part-time nuclear physicist, now lectures on thermodynamics.*

Remember that the second law of thermodynamics - one of powerful evidences for creation - is that neither energy nor matter can be either created or destroyed.

Um… Bryan? That's the first law of thermodynamics, also known as the conservation of energy. The second law states that the entropy of a closed system never decreases.

http://www.youtube.com/watch?v=2kZtoVc1gQw

A brief digression. Did you notice how he emphasizes the word law? That is a sure sign that the speaker doesn't understand what a scientific law is or how it differs from a basic principle and from a theory.

Now he makes a claim about the origin of the universe.

There is nothing in inside the observable universe that can explain the origin of matter or energy.

Why is it that people like Bryan Fischer make statements like this as though they are undisputed facts? The origin of energy (mass is just one form of energy) is an open scientific question. Lawrence Krauss and Brian Greene are just two physicists who have written popular accounts on the nature of matter and energy.

So what is the logical conclusion? Someone outside the universe put it there.

Logical conclusion? Fischer must never have taken a course in logic. First he assumes the truth of his premise. Then he creates a false dilemma - either there is no one or there is someone. Notice the lack of something. Of course, the someone he has in mind is his version of the christian deity.

The universe is headed toward a heat death.

Now Fischer gets the 2nd law essentially correct. The universe will according to current models keep expanding, increase in entropy, and grow very cold.

This is a scientific law predated by the psalmist back in 900 B.C.

Wait for it.

Of old you laid the foundation of earth, and the heavens are the work of your hands. They will perish, but you will remain.

Psalm 102, verses 25 and half of 26.  Then he makes a statement as though it were a fact.

Matter and energy are not eternal. It had a beginning and it's got an end. 

Earlier he calls the eventual state of the universe a heat death. I think he does this so his listeners can conjure in their minds the biological meaning of death, but in physics, this term first coined by Lord Kelvin means that the universe has cooled to such a point that the universe's entropy is maximized and the energy in the universe has been uniformly distributed.

My question about Fischer and others like him is 

Are you deliberately misleading your followers about science 

or do you really believe this crap?"

If you'd like to hear Fischer discuss geology and paleontology, chick here. You will be entertained when he claims only eyewitness accounts can be trusted.

*Thanks to Right Wing Watch for "monitoring and exposing the activities of the right-wing movement."

Sunshine, Lollipops, and Rainbows

No more sunshine and rainbows for Naveena Shine. Lollipops,maybe. Naveena is the Washington woman who for 47 days attempted to subsist only on sunshine. As I wrote earlier this month, she tried to see if a person could subsist on the "nutritional source already embedded within our body/mind/Spiritual systems that can give us exactly what we need to be healthy and well." 

CREDIT: Ellen M. Banner/Seattle Times

After losing 33 lbs, The Seattle Times reports she's quitting, not because she slowly killing herself, but because "she’s run out of money, and in part because of the public reaction."  On her site Living on Light, she writes that the rest of us are "by no means ready to receive the information I am attempting to produce." She fears that if she were to continue and was successful, we would all rush away from steaks, salads, asparagus, chicken, and all that delicious food we consume and try to live on air and sunshine.  She likens this to "giving a loaded shotgun to a baby."

The funniest paragraph in the Time article begins

Doctors have warned that it is not possible for humans to photosynthesize...

Is civilization really at the point where it takes a physician to warn people that humans aren't plants?

p.s. If you haven't clicked on either of the first two links, then you must click here.  I have a soft spot for Leslie Gore.

A Diet Guaranteed to Work

This is Naveena Shine on May 30, the first day of her diet.  Her diet is the simplest one I have ever read.  Don't eat.

Yes, do not eat. To be fair, Ms. Shine is not attempting to lose weight, but to see if humans can thrive without "carbon-based food." She thinks that "we have a nutritional source already embedded within our body/mind/Spiritual systems that can give us exactly what we need to be healthy and well." This is Living on Light. She cites people called Breatharians and Sungazers. One leading Breatharian Jasmuheen asserts

when we are well tuned and four body fit, we can access an inner power which has the ability to love us, guide us, heal us and also nourish our cells. As vast multi-dimensional beings, we have limitless access to a source of internal nourishment (prana-chi) that constantly bubbles champagne-like throughout the matrix of life.

Is she thriving?  Here is a picture from June 8. 

You can follow her on Facebook and YouTube.

As a physicist, I would like to point out that what we are observing here is a good example of the Second Law of Thermodynamics.  In attempting to be a closed system, Ms. Shine's entropy is increasing, much more rapidly that nature intends. She should stop snacking on Light immediately and scarf some proteins, fats and carbohydrates.

Applying Physics To Cooking

Need to separate the yolk from the egg white?  All you need is a slight difference in air pressure.  Watch.

Dr. Oz's Diet Advice

I was really bored yesterday, August 6, 2012.  Flipping through the channels, I came upon the Dr. Oz show, and I wondered what woo he was pushing today.  Sure enough, he begins the show with metabolism boosters.  

I immediately began to wonder whether a person can really boost their metabolism by simply drinking tomato juice spiked with a little Tabasco sauce and lime juice, but then he said this.

"And while wine snobs may not approve, adding ice chips to your red wine forces your body to burn calories, as it has to use its own energy to warm the liquid to body temperature."

Let's see what science has to say about this.

One learns in both physics and chemistry courses that to raise the temperature of any substance it takes an amount of energy equal to Q = mcdT where m is the mass of the substance, dT is the final temperature minus the initial temperature, and c is called the specific heat. The specific heat takes into account all the complicated physics and chemistry of how energy is distributed among the atoms and molecules.

I went to my freezer and looked at a ice cube - technically it's not a cube, it's a rectangular solid, but I'm being pedantic.  I don't have a kitchen scale, so I'll determine its mass by measuring its dimensions.  My cube is 5 cm by 3 cm by 3.5 cm or about 53 cm³.  The density of ice is 0.998 grams per cubic centimeter, so I can calculate its mass by multiplying the density by the volume.  Therefore, my ice cube's mass is 53 grams.

The ice will melt and cool the wine as cold as 0ºC.  After you drink the wine, your body will warm the liquid to body temperature, about 37ºC.

The specific heat of water is 1 calorie per gram per Celsius degree.  So your body will use 

Q = (53 g)(1 cal/(g ºC))(37ºC–0ºC) = 1961 calories.

But I have to correct something here.  A food calorie is different from a calorie.  A food calorie, also called the Calorie (notice the capital C), is equal to 1000 calories.

So your body has to expend almost 2 Calories to warm the cold wine.  I think you can burn 2 Calories by breathing for a whole minute.

UPDATE: Oops! I made a mistake here.  Your body has to warm all the liquid, not just the melted ice.  If you have a standard serving of wine, 6 oz., then your body expends 8.5 Calories.

You can do a little better by eating the ice, since your body has to melt the ice, too.  I''ll spare you the details, but that takes a whopping 4 10 Calories! Assuming you drink the wine, too.

Even if you live a sedentary lifestyle, you will burn at least 1200 Calories every day by just existing. This is your metabolic activity. If you are active, your metabolic activity can be as high as 3000 Calories.  

If you want a little dieting advice, I share with you the only diet proven to work.  

The Thermodynamic Diet

The 1st law of thermodynamics states that one cannot create nor destroy energy.  All that can be done is to convert energy from one form to another.  Your body converts chemical energy in the food to kinetic energy (energy of motion) and thermal energy (you may call that heat, but that's technically incorrect).  Any energy not converted into these two forms may be converted into another form of chemical energy; that is, weight gain.

So the thermodynamic diet is burn more calories than you ingest.