Experiments in weighlessness on the ISS

One of NASA's astronauts has been doing some instructive and interesting experiments on the International Space Station described here.

"NASA and the American Physical Society (APS) have partnered to share unique videos from the International Space Station with students, educators and science fans from around the world. NASA astronaut Don Pettit will use everyday objects from Earth to demonstrate physics..."

The Earth - getting bigger or smaller?

This article from the BBC compares the ways in which the Earth is gaining and losing mass. It makes excellent discussion material for sixth form Physics students since it involves gravity, astronomy, mass-energy conversion and climate change all in one discussion!

"Using some back-of-the-envelope-style calculations, Dr Smith, with help from physicist and Cambridge University colleague Dave Ansell, drew up a balance sheet of what's coming in, and what's going out. All figures are estimated.

By far the biggest contributor to the world's mass is the 40,000 tonnes of dust that is falling from space to Earth, says Dr Smith."

Videos - cathode ray oscilloscope

Some useful links for CRO videos suitable for A-level or university from Youtube :

GCE (A-level) Physics E29 The Oscilloscope - YouTube 
Good clear introduction to basic CRO use mostly using diagrams. Examples of making measurements of voltage and frequency. 11mins

The Oscilloscope - YouTube  http://www.youtube.com/watch?v=5yNDSkQBEy0&feature=related
A good introduction to a more complex (dual-beam) CRO. The CRO is shown in action. 5mins

AC vs DC Explained and How to Use an Oscilloscope - YouTube 
Another look at basic CRO use using a real CRO and also using a CRO with a PC. 12mins

Nanotechnology

See the other blog for an item on nanotechnology. This a bit advanced but is important as an area of applied Physics which is drawing increasing attention.

Faster-than-light neutrinos - latest news

I did not expect to report on this again so quickly but the people at CERN have been able to repeat their experiment with greater accuracy and certainty. And the result confirms the previous findings! From a BBC report (the BBC is usually quick to report science stories and does so with commendable clarity):

"When the Opera team ran the improved experiment 20 times, they found almost exactly the same result."

"This additional test we made is confirming our original finding, but still we have to be very prudent, still we have to look forward to independent confirmation. But this is a positive result."

As mentioned above, independent confirmation is needed. That is to say confirmation of the results by other physicists elsewhere using different equipment. Until this happens there will be a lot of skepticism about the result.

Faster-than-light neutrinos - follow-up

Many possible explanations have been offered for the strange and unexpected results reported in the last post. A new experiment is underway to test these theories - the results will be known next month. Patience is another quality required for good science!

According to a BBC report:

"Scientists who announced that sub-atomic particles might be able to travel faster than light are to rerun their experiment in a different way.

This will address criticisms and allow the physicists to shore up their analysis as much as possible before submitting it for publication.

Dr Sergio Bertolucci said it was vital not to "fool around" given the staggering implications of the result.

So they are doing all they can to rule out more pedestrian explanations."

Faster than light?

Recent results from an experiment measuring the speed of neutrinos implies that they travel very very slightly above the speed of light. This has caused considerable excitement and some consternation in the scientific world. The physicists responsible are asking others to examine their results. See this BBC report and this Physics World report.

There are many aspects of this worth looking at:
- why is the speed of light considered a universal speed limit?
- what are neutrinos? See these articles.
- what experiment were they doing? They did not set out to test this principle.
- this episode shows how science should be conducted