Albert Einstein - 70 years

Einstein is a scientist every science student should definitely know something about. He passed away 70 years ago this year.

According to an item in the Scientific American:

"Einstein is the most famous and beloved scientist of all time. We revere him not only as a scientific genius but also as a moral and even spiritual sage. Abraham Pais, Einstein's friend and biographer, called him "the divine man of the 20th century." 

To New York Times physics reporter Dennis Overbye, Einstein was an “icon" of "humanity in the face of the unknown.""

For more there is plenty at Wikipedia, of course, and here are two videos on Youtube:
How Einstein discovered E=Mc2
Albert Einstein documentary

New gamma-ray spectroscope

Some exotic physics in this device (developed at Vanderbilt and Fisk Universities) with some exciting space applications may get the interest of students.

"...a new generation of gamma-ray spectroscope that appears perfectly suited for detecting veins of gold, platinum, rare earths and other valuable material hidden within the asteroids, moons and other airless objects floating around the solar system" 

"The key to the new instrument is a recently discovered material, europium-doped strontium iodide. This is a transparent crystal that can act as an extremely efficient gamma-ray detector. It registers the passage of gamma rays by giving off flashes of light that can be detected and recorded."

Turbulence

A good example of a phenomena which seems simple but which gets very complex - water flowing through a pipe.
At low speeds the flow is smooth and predictable but at higher speeds turbulence makes things complicated. According to this report:
"A team of researchers from Austria, Germany and the U.K. has succeeded in building a model that shows the process that occurs when a liquid moves from a smooth state to one of turbulence inside of a pipe."
This is a good item to use to introduce in a general way the modelling of physical processes.

Challenging Concepts in Physics

Need help with difficult concepts? Advanced high school or starting university level? This MOOC at EdX should help. It is done by experienced teachers and includes:
 Acceleration
 Force Diagrams
 Momentum
 Rotational Motion
 Angular Momentum
 Standing Waves
 Conservation of Charge & Energy in Circuits
 Electrostatic Fields
 Gravitational and Electric Potentials
 Electromagnetic Induction
 Thermodynamics
 Pressure, Force & Flow in Fluids
 Diffraction & Interference
 Atomic Transitions

The course uses short instructional videos, on-screen simulations, interactive graphs, and practice problems.
Sounds really useful.

Reflections on a mug of tea

A question for students (its good to have an open ended question sometimes):

A ceramic mug of hot tea sits on a wooden table. Discuss how it cools. (Yes I know the picture does not show a wooden table... :) )

Convection from the surface is important.
Conduction through the sides and then cooling by convection significant too.
Cooling by radiation happens too although the temperature difference is small.
Conduction through the base not important as the ceramic is a poor conductor and the wood is worse.

How can the cooling be enhanced?
Convection is easily speeded up by a higher flow of air (blowing, fan, breezy location etc).
Putting a spoon in the cup increases conduction loss.
Using a black mug will help a little.
Drastic methods! (if you are late for work) - pour into another vessel, add ice etc.

MOOCs and the Caribbean

Have just posted an item about this in the other blog - see here.

New discovery in subatomic physics

This is a bit exotic but I have nothing else bookmarked for this month. The first pentaquark has been reported. This is a particle composed of five quarks - very strange but predicted. Normal particles such as protons are composed of three (see diagram) so it is like one and two-thirds of a proton - kind of.

Here is a good article explaining this starting from Rutherford's discovery of the compact nucleus of the atom over a hundred years ago.

CXC Physics on-line resources update

Following changes the CXC website now offers syllabuses and past papers as downloadable ebooks through their 'store'. Past papers cost money to get but the syllabus has a cost of $0 which means it can be downloaded free but it is neccessary to create an account and go through the shopping cart thing.

Inside a radiation detector

This picture shows the board of a gamma-ray detector known as a Geiger-Muller counter.  Gamma rays are detected by the tube, counted and the count shown on the LCD. The words at the top of the board warn of high voltage (400-500V).

The type of radiation detected depends on the tube used.
See Wikipedia for more.

Cosmology

A good introduction to the subject!

Closing off modeling climate change

Have just finished the course at EdX which I mentioned in two previous posts (first, second).

As part of an assignment I looked at historical temperatures for Georgetown and Timerhi. Georgetown has one of the most complete sets of data for this part of the world. Here is a graph showing the annual average temperatures (degrees Celsius) from 1850 (Georgetown orange, Timerhi green). It is clear that there is an upward trend which has accelerated from about 1950. The trend for Georgetown is about 0.2 degrees rise per decade and the mean temperature seems to have risen by about one degree since 1950. Global temperatures show similar results.

One closing topic was short-term mitigation - what we can do now to reduce the problem. The lecturer pointed out that there are things that can be done such as reduce heat loss by homes in cold countries, change agricultural practices to trap more carbon and increase energy efficiency of transportation. Another is to change our life style and diet.

It seems to me more than ever what we need is better working together to tackle world problems and less short-term politics.

More on modeling climate change

Am still doing this course as mentioned in the previous post. Heavy going at times with topics such as:

• greenhouse gas physics
• atmospheric feedbacks
• carbon cycle
• perturbed carbon cycle
• solar and glacial cycles

Most weeks have models to set up using spreadsheets or programming. Some assignments require access to one or more of the Climate and Carbon Cycle Models available from University of Chicago.

One interesting prediction - if we stopped producing carbon dioxide today it would take the earth thousands of years to recover, may be hundreds of thousands. And we would not feel the full effect of what we have produced so far for hundreds of years during which the ice sheets would continue to melt and the sea level to rise...

MOOC - climate models

Am now doing another course at EdX called "Modeling Climate Change". Again this involves quite a bit of physics. The focus really does seem to be on modelling and so far seems to be a good introduction to some serious computational physics. A good course for linking with physics at the University of Guyana. More next month.