“Science is built up of facts, as a house is built of stones; but an accumulation of facts is no more a science than a heap of stones is a house.”

Henri Poincare (1854-1912)Science and hypothesis(1905)

Why Airfoils Work

Bernoulli vs NewtonNeedless to say, the disagreement is modern;

airfoils did not exist in Newton or Bernoulli’s time

Why Airfoils WorkNewton supporters say…1. In order for the airfoil to go up, air

must be redirected down (3rd Law of Motion).

2. Therefore, the angle of attack is important because air that hits the bottom of the wing gets bounced down.

3. (Unstated) The top of the wing plays no role.

TRUE

TRUE, BUT LESS THAN HALF THE STORY

FALSE

Why Airfoils WorkBernoulli supporters say…1. The air is redirected up on top of the

wing.2. That air travels a longer distance.3. The air must come back around to

meet the air on bottom in the same time.

4. Therefore the air on top travels faster5. By Bernoulli’s equation, the faster air

on top exerts less pressure.

TRUE

TRUE, BUT NOT RELEVANT

FALSE

TRUE, BUTNOTFOR THEREASON GIVEN

Why Airfoils WorkThe truth is that the 3rd Law of Motion and the

Bernoulli Effect are both relevant.

It is true that air is forced down (downwash), but this is mostly due to a speeding up of the air on top of the wing, which is a Bernoulli Effect phenomenon.

The effect is so pronounced, that air passing over the wing actually passes around the wing in a shorter time than air passing under the wing.

Why Airfoils Work

Calculation shows that the positive pressure on the bottom of the wing is insufficient to explain the lift.

It is the negative pressure on top of the wing that accounts for most of the lift.

Why Airfoils WorkIt should be noted that wings are three

dimensional objects.

The downwash is strongest near the body of the plane and weakest at the wingtips.

This effect produces vortices in the downwash

more info:http://www.av8n.com/how/htm/airfoils.html

The “Corilois Effect”

The Coriolis Force

• When explaining draining sinks, tubs, and toilets, the influence of the Coriolis Force is very small.

• The shape of the bowl, the location of the drain, and how the bowl is filled determine the direction which water flows out of everyday objects.

• http://www.ems.psu.edu/~fraser/Bad/BadCoriolis.html

Einstein Said It

Beware of the “Mark Twain Effect”. Sayings are sometimes attributed to a person who is thought to be witty, wise or who is already extensively quoted.

Witty sayings are often attributed to Mark TwainWise sayings are often attributed to Albert Einstein, the Dalai LamaOne liners are often attributed to George Carlin

Einstein Said ItWhich of these cannot be found among Einstein’s

writings? source: The Quotable Einstein, edited by Alice Calaprice

1. Imagination is more important than knowledge.

2. Few people are capable of expressing with equanimity opinions which differ from the prejudices of their social environment.

3. I do not know how World War III will be fought, but World War IV will be fought with sticks and stones.

4. When the blind beetle crawls over the surface of a globe, it doesn’t notice that the track it has covered is curved. I was lucky enough to have spotted it.

cannot

cannot

cannot

cannot

Einstein Said ItIf you are really interested in what

Einstein said, I recommend:

Albert Einstein, Ideas and Opinions

If you are only interested in quotes:

The Quotable Einstein, edited by Alice Calaprice

Weightless in space

Are astronauts “weightless” when they are in orbit around the Earth?

A Microgravivty Environment

• An Astronaut’s weight is defined as the gravitation force acting between the astronaut and the earth.

• Using Newton’s Law of Universal Gravitation, the weight of a 70 kg(150 lb) astronaut orbiting at 400 km is 131 lb (88% of his/her weight on Earth)

The Appearance of Weightlessness

• Astronauts appear to be weightless because, just like the spaceship they are in, they are in freefall.

• If gravity stopped in space, how could the Earth’s moon influence the ocean’s tides?

Earthquake PredictionThere was a time when we thought that with enough

research we could predict earthquakes.

We were wrong. Current models suggest that fault lines organize themselves into a critical state in which earthquakes can be triggered by the smallest changes.

Such systems have what is known as “long memory” --- every rock, crack, and movement would have to be known to extreme precision in order to predict. (Sensitive dependence on initial conditions.)

more info: Ubiquity: Why Catastrophes Happen, by Mark Buchanan

Tsunami Prediction

Tsunami detection is possible, but arrays of such systems are very expensive and may not be worth the cost in all oceans.

Did you know that the Sumatra earthquake that spawned the tsunami changed the earth?

1. The North Pole shifted 2.5 cm.2. The Earth is slightly less oblate.3. The day is 2.68 microseconds shorter.

more info at: http://earthobservatory.nasa.gov/Newsroom/NasaNews/2005/2005011018159.html

We only use 10%

Using our brains

• We use 100% of our brains.• Difficult to track down the source of

this number.• This number is often referenced

when explain the “Supernatural” abilities of psychics

• http://www.csicop.org/si/9903/ten-percent-myth.html

Intelligent Design and Evolution

Myth #1: Intelligent Design is a unitary idea.

Reality: It can be…1. The attempt to cast doubt on evolution.2. The hypothesis that empirical evidence

exists that the universe was designed supernaturally and did not happen naturally.

3. The religious conviction that the natural processes of the universe must have been designed.

Intelligent Design and EvolutionMyth #2: There are doubts about evolution.

Reality: It is the most basic assumption of all biology.

1. It is not “just a theory”.2. Genetic Mutation is an observable fact.3. Selection is an observable fact.4. That Genetic Mutation and Selection can

produce new species is an observable fact.5. It is not just “survival of the fittest”.

Myth #3: Empirical evidence exists that the universe was designed.

Reality: The arguments cannot be based on empirical evidence.

1. Catch-22. One could argue it both ways: if life is unlikely then it takes the supernatural to explain it. If it is likely, then the universe was designed to have life.

2. Likelihood arguments assume that we know the intentions of the designer. This becomes circular.

3. Likelihood arguments assume we know the probability space of the parameters that go into designing a universe.

Intelligent Design and Evolution

Myth #4: Belief in Intelligent Design and Evolution are mutually exclusive.

Reality: Many folks believe both. Evolution is based on physical evidence alone. Intelligent Design goes beyond the physical evidence, and science alone can neither confirm nor refute it.

Thus there is no contradiction in believing that Evolution (or Gravitation or Quantum Electrodynamics) could have been designed to be the way it is.

Intelligent Design and Evolution

more info at: http://www.mrmont.com/idcsieve/empiricaldoubts.html

International Protocols

They can work.

Case in point: The ozone layer is no longer thinning and may have improved at midlatitudes

source: Chemical & Engineering News, September 5, 2005, p. 13

Global WarmingSome have argued that the Earth is not warming,

and even if it is, it is a natural process.

Although there was some doubt a decade ago, there is no doubt now that the Earth is warming up.

Furthermore, recent statistical analysis now shows that it is almost certainly our burning of fossil fuels that is the cause.

Here is some data from journals I read...

Global Warming• Global average surface air temperature rise since 1900:

1.2° to 2.4° F (all methods of measurement agree) with a further increase of 2.5° to 10.4° F expected by the end of the century.

• The 11 warmest years since instrumental records have been kept have all occurred since 1990.

• The warming observed in the Northern Hemisphere has been greater than any other during the past 1000 yrs.

• Increased cloud cover and precipitation has been observed at the mid to high latitudes in the Northern Hemisphere, as well as decreases in precipitation in the subtropics.

• Sea levels are up 10 to 20 cm from thermal expansion and melting glaciers.

• Arctic temperatures have risen faster than anywhere on the planet; perennial ice is decreasing at a rate of 3% per decade.

Source: “Climate Change” Chemical & Engineering News, December 15, 2003

Global Warming

• The Earth is now absorbing 0.85 ± 0.15 W/m2 more energy from the sun than it is emitting, according to precise measurements of ocean heat content over the last 10 yrs.

• Due to the “thermal inertia” of the oceans, drastically reducing CO2 emissions today will not result in a reversal of the warming for some time.

Source: “Earth’s Energy Imbalance: Confirmation and Implications” Sciencexpress.org (online version of Science) April 28, 2005

Global Warming1. Precise ocean temperature

measurements have ruled out solar variability and volcanic eruptions as causes of the warming.

2. The same rise in ocean temperature is accurately predicted by climate models which assume human generated CO2 forcing.

Source: “Penetration of Human-Induced Warming into the World’s Oceans” Sciencexpress.org (online version of Science) June 2, 2005

Global Warming• Rapid climate change is possible,

according to both geological records and climate models.

• Rapid could mean decades.• The North

Atlantic Circulation question.

Source:“The Discovery of Rapid Climate Change”Physics Today August 2003 pp. 30-36.

Genetics of Eye ColorThe old model had only one gene

with two alleles: blue (recessive) and brown (dominant).

The current model assumes two genes: BEY 2 with two alleles: brown and blue, and GEY with two alleles: blue and green.

Brown is dominant over green which is dominant over blue.

Genetics of Eye Color

There is simulation of the model online at http://www.athro.com/evo/gen/genefr2.html

The current model cannot account for hazel, gray, or shades of brown, though.

More info at:http://www.seps.org/cvoracle/faq/eyecolor.html

Thanks for coming

Dave Montalvodmontalvo@umasd.org

www.mrmont.com/teachers

Pete Vreelandpvreeland@umasd.org

www.thesciencefactory.org