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.

St. Patrick Was an Engineer?

If you believe the engineering students at my alma mater, the University of Missouri, St. Patrick did more than drive the snakes from Eire. From the MU Archives:

The students of the College of Engineering at the University of Missouri-Columbia were the first to "discover" that St. Patrick was an engineer. Since 1903, UMC engineering students have celebrated St. Patrick's Day (March 17) as a holiday set aside for engineers. This celebration has developed into a week of festivities, including lab exhibits, a canned food drive, a knighting ceremony, St. Pat.'s Ball, and the coronation of the King and Queen of the engineers.

According to engineering tradition, the discovery that St. Patrick was an engineer began with the excavations for the Engineering Annex Building. During the excavation, a stone was unearthed with a message in an ancient language. This message was translated into "Erin Go Bragh." Although those of Irish descent may recognize "Erin Go Bragh" as "Ireland Forever," the engineers loosely translated this phrase as, "St. Patrick was an engineer." The stone, now known as the Blarney Stone, is an integral part of the St. Pat. festivities. The engineers looked to the legend that St. Patrick drove the snakes out of Ireland as proof of his engineering skills. They further credit St. Patrick with the invention of calculus. 

For more on Engineering Week at Mizzou, follow this link.

Use the Force, Luke

The United States will not be building a Death Star.

Death Star from Star Wars: Episode IV - A New Hope (1977). CREDIT: Lucas Films

On November 14, 2012, John D. from Longmont, CO petitioned the White House to "secure resources and funding, and begin construction of a Death Star by 2016."  The appeal suggests that "by focusing our defense resources into a space-superiority platform and weapon system such as a Death Star, the government can spur job creation in the fields of construction, engineering, space exploration, and more, and strengthen our national defense." 

The White House has responded.  While the Obama administration is supportive of the petitioners desire for job creation and maintaining a strong national defense, the government will not be allocating scarce research and development funds on a Death Star for three reasons.

Reason #1:

The construction of the Death Star has been estimated to cost more than $850,000,000,000,000,000. We're working hard to reduce the deficit, not expand it.

Reason #2:

The Administration does not support blowing up planets.

Reason #3 and the absolute best reason for not building this weapon of mass destruction:

Why would we spend countless taxpayer dollars on a Death Star with a fundamental flaw that can be exploited by a one-man starship?

Physics Helps Reduce Violence Against Women

More than 300,00 people in Darfur have been killed, and more than 2 million have fled their homes to live in huge refugee camps. Although they receive food aid, ones pressing problem remaining is cooking their food.

As described by Cookstove Projects, 

Due to the size of the IDP camps (some camps have more than 100,000 residents) and the desert-like terrain, wood is increasingly scarce. With deforestation, displaced women must walk up to seven hours to find a single tree, risking assault every step of the way. To avoid danger, some Darfuri women purchase wood from vendors... by selling the very food they need to feed their families. While the tangle of political and ethnic tensions underlying the Darfur conflict may seem beyond resolution, the solution to this one problem is clear: women in Darfur need a better stove.

Lawrence Berkeley National Laboratory physicist Ashok Gadgil and other LBNL scientists went to Darfur in 2005 to see the situation for themselves. As Dr. Gadgil says, “In terms of the physics end of it, of course you want high combustion efficiency, where you’re not left with charcoal and smoke, which is where some of the chemical energy could go,  and you want good heat transfer efficiency, so you’re not just heating the kitchen air but putting the heat into the pot.”

Just this past May, the US Agency for International Development awarded $1.5 million so that these stoves can be distributed in Darfur and Ethiopia.

Flying Aircraft Carriers: Physics and Engineering in The Avengers

CREDIT: Marvel Studios

I saw the Avengers on Memorial Day.  Awesome movie, and if you've read one of my early blog posts, Transformers 3 - Dark of the Moon, you might guess I sometimes think about physics during the movie.  One thing that caught my attention was the flying aircraft carrier.  What would it take to make one fly?

Thanks to Wikipedia, I found some specifications for a modern US navy supercarrier.  They are 333 meters long (1,092 ft) and 78 meters wide (260 ft), and its displacement is 100,000 long tons which is equal to 224,000,000 pounds and 101,600,000 kg.  It is powered by two nuclear power reactors that provide 190 megawatts.

Now for science!

There was a shot in the movie when two of their fans were shut down and the ship was plummeting.  The altimeter read between 17 and 18,000 ft.  So I will begin by assuming they were cursing at 30,000 ft.  This is also where many commercial flights travel.  I will also assume that it takes about 30 minutes to reach cruising altitude.

CREDIT: Marvel Studios

Now I can estimate the acceleration.  Kinematics, the study of motion, says that for a body initially at rest, the acceleration is given by

Plugging in gives a value of 0.006 m/s/s.  For you non-students of physics, this means that for every minute, the carrier goes almost 1 mph faster.

Now for Isaac Newton.  To produce this acceleration, Professor Newton says that unbalanced forces have to act on the carrier.  Newton's 2nd law:

Here I will have to use the ship's displacement as its mass.  The displacement measures how much water an object pushes out of the way.  Rather than trying to calculate the ship's mass, I'll take the shortcut.  The total unbalanced force is about 570,000 Newtons.

There will be two forces acting on the ship - the thrust and the gravitational force (commonly referred to as the weight).  The thrust has to be 570,000 Newtons larger than the weight.  We can find the weight by multiplying the mass by the gravitational field (9.8 N/kg).  Therefore the thrust is approximately 10,000,000,000 Newtons.

The total energy used in both speeding up the ship and raising it can be found by multiplying the thrust by the distance.  

Since power is the rate at which energy is converted, we can take the energy and divide by 30 minutes.  To raise SHIELD's ship requires 5,000,000,000 Watts; that's 5.0 gigawatts!  Earlier I noted that the 2 reactors aboard a US carrier provide 190 megawatts, SHIELD needs 52 nuclear reactors.

Now for those fans providing the thrust.  To try to calculate the thrust of a ducted fan, one needs an extensive knowledge of fluid dynamics and aeronautical engineering plus a powerful computer.  I'll take the quick path to the answer.

With a 0.16 second Google search of "thrust fan specifications", the first result was for Ventry Solutions, Inc.  They sell a 24 inch ventilation fan that supplies 108 Newtons of thrust.  I'll scale that up for the ducted fans seen in the movie.  

Judging from the photo above, the fans have a diameter of about 40 meters (130 ft).  If - a very big if - the thrust is proportional to the diameter, then one fan can give 7100 Newtons.  Uh oh.  7100 Newtons per fan; 10,000,000,000 Newtons needed.  

14 million of them.

Is Your Baby in a Bad Mood?

Wouldn't it be wonderful if a parent of an infant knew what a baby was feeling?  Imagine knowing the reason why the baby is crying and not having to wonder if it's hunger, sleepiness, or a wet diaper.

Exmobaby to the rescue!  Exmobaby is "a next generation “smart garment” line of apparel specifically designed for newborns and infants."  The onesie has imbedded in the fabric conducting fibers that measure heart rate, skin temperature, and movement.  A transmitter then sends data every minute to a PC within 100 feet. [What!  No Mac version!] Software on the computer interprets the data, sends it to a website that will send alerts to cell phones, email accounts, or instant messaging accounts.

My first thought is what happens when a malfunction occurs. Suppose the heart monitor and the motion sensor fails.  A mother gets a text message that her babies heart isn't beating and the baby isn't moving.

My second thought is - isn't this onesie just weird.  Plus, isn't this company playing on the fears of first-time parents.  I should say well-to-do first-time parents.  While not available for purchase yet, distributors can buy one for $1000.  Less affluent parents will just have to rely on less current technology.

Santa Claus Science - Part 1

How does Santa do it?  Deliver all those presents to the children of the world.  Let's consider what his task entails.

There are 6.79 billion people in the world, 1.855 billion are children.  Sad as it may seem to some, but I don't think Santa visits all the good children of the Earth.  Santa only visits Christians.  Since Christians are 32% of the Earth's population, it seems reasonable to assume Santa has to visit 594 million youngsters under the age of 15.

Suppose each child gets one present, and that present has a mass of 1 kg.  (2.2 lb.s of weight for you non-SI people).  Santa gets to lug around 564,000 tonnes of toys.  Reindeer can pull up to twice its weight.  The jolly one then has to harness over 3 million reindeer to his sleigh. 

Speaking of the sleigh - let's assume each present fits in a cubic box 15 centimeters (6 inches) on a side.  With 594,000,000 presents to deliver, Santa is going to need a large sled.  He needs to haul 2 million cubic meters of presents.  Since the world's largest supertanker has a capacity of 670,000 cubic meters, the rotund one will need three of them and an additional 8 million reindeer.

11 million reindeer.   Imagine all that poop.

A Lesson on Wine and Physics

There's a field of physics engineering called statics.  It is concerned with the forces and torques acting on objects at rest.  If you want to build a bridge, you have to understand statics.

Here's an example of either poor engineering of store shelves or of incorrect loading of those shelves.

Now let the crying commence..