Anselm33;7263558:
yo alec, are you saying that conventional detectors could detect single photon events? I’m not disputing that claim–that kind of experimental technique is above my pay scale (set in nuclear magnetons)…

--but I find it suprising. Is there an online reference somewhere, cause if it hasn’t been done it should be?
Anselm
PS–I did find a link, but at Harvard—a little above secondary school, but not too much.
Thanks for the information.
fas.harvard.edu/~scdiroff/lds/QuantumRelativity/SinglePhotonInterference/SinglePhotonInterference.html
Well, there you go - they are using a low light level camera that has two-stages of image intensifier - although not terribly sophisticated it’ll be quite pricey I suspect. Its quantum efficiency is only about 0.1% so it only detects one in a thousand photons, but because you can have 300 - 600 million photons per second and still have less than one in the apparatus at any instant, the low quantum efficiency doesn’t matter. The advantage of their setup is that you can see the fringes building up point by point on the storage scope, whereas in the setup I suggested you have to physically move the detector (photomultiplier or avalanche photodiode) across the image plane and count photons and then subsequently plot their density. But the point is that in either case, you actually could do this in a first class school lab project. It’s really not that sophisticated. Google PMTs and APDs used in Geiger mode. It’s a groovy experiment because it demonstrates the bizarre behaviour of light at first hand.
Alec
evolutionpages.com
Alec (hecd2), thank you. I love physics!

The Office of Science –U.S. Department of Energy has a wonderful website. Here is a small section from the document.
What is Physics?
*Physics is all around us. It is in the electric light you turn on in the morning; the car you drive to work; your wristwatch, cell phone, CD player, radio, and that big plasma TV set you got for Christmas. It makes the stars shine every night and the sun shine every day, and it makes a baseball soar into the stands for a home run.
Physics is the science of matter, energy, space, and time. It explains ordinary matter as combinations of a dozen fundamental particles (quarks and leptons), interacting through four fundamental forces. It describes the many forms of energy—such as kinetic energy, electrical energy, and mass—and the way energy can change from one form to another. It describes a malleable space-time and the way objects move through space and time.
There are many fields of physics, for example: mechanics, electricity, heat, sound, light, condensed matter, atomic physics, nuclear physics, and elementary particle physics. Physics is the foundation of all the physical sciences—such as chemistry, material science, and geology—and is important for many other fields of human endeavor: biology, medicine, computing, ice hockey, television…the list goes on and on.
A physicist is not some geek in a long white coat, working on some weird experiment. Physicists look and act like you or me. They work for research laboratories, universities, private companies, and government agencies. They teach, do research, and develop new technologies. They do experiments on mountaintops, in mines, and in earth orbit. They go to movies and play softball. Physicists are good at solving problems—all kinds of problems, from esoteric to mundane. How does a mirror reflect light? What holds an atom together? How fast does a rocket have to go to escape from earth? How can a worldwide team share data in real time? (Solving this last problem led physicists to invent the World Wide Web.) . . .*
er.doe.gov/Sub/Newsroom/News_Releases/DOE-SC/2005/What_is_Physics.htm
Alec (hecd2) I really like your website too.

Both websites give me a sense of well being (Health)
who.int/about/definition/en/print.html