Is Light a Particle or a Wave?

 

Now there is a question that drove many scientists over the hill and completely around the corner.

Einstein really threw in a wrench when he proposed that light consisted of both particles and waves but the kicker was that only one state could be represented at a time as both states collapse even though only one is being "viewed".

It now seems that restriction is a thing of the past.  Scientists at the EPFL (Ecole polytechnique fédérale de Lausanne) have succeeded in capturing light’s wave-particle duality, in a what can only be described as tremendously exciting first-ever image.

Light Pollution is Worse Than You Think

Many observatories are now threatened by a very real pollution problem.   A problem that could make many of today's best visible light observatories useless in a matter of a few decades!  This pollution is an easily avoided problem of too much night time light pollution.

Check out the video on this worsening problem and steps that are being taken to preserve the night time sky......

I really love any instructional that deals with the dual/single slit experiment, and this one (which caries on from his last video) is no exception. Here we see an example again of the 1801 Thomas Young experiment, which passed a single photon against a dual slit plate. It wasn't until the early 1900s that light energy is not as evenly spread as one would expect in a wave. It acted more like "packets" of energy, hence the Photon. Check out the informative video below:

Double Slit Experiment: easily reproducable

I know....one of my favorite hobby horses this one.  But I truly love experiments that screw with our perception of our environment.  One of the fundamental ones deals with our perception of frequencies in the visible light band.

The famous dual slit experiment which showed that light was a wave was first put forth by Thomas  Young in the early 1800.  In this video, we are shown that complicated machinery to demonstrate the phenom.  

Check out the video.

Slow Light - is it possible? What are the uses?

I remember reading Bob Shaw's 1968 short story "Light of Other Days many years ago about Slow Light. In this story all the windows in the house were made of slow glass. This glass was made of a material that slowed light to a crawl. The light that entered it on one side took years to pass through. The thought being that you would set out a sheet of slow glass in a picturesque local for a number of years and then install them in frames that would act as windows. The idea just blew me away.

Is it possible? Very likely... Lets look at light. the posted speed limit for light is 300,000km a second. But that is only in a complete vacuum. In real life light travels MUCH slower. What slows light down? Well any ole atom will do the trick. An atom will absorb a photon and re-emit it, imparting a delay. This is called the absorption/re-emission cycle. Now I hear the screams "photon HAVE to travel at C!" and in truth the "slowing" is just an illusion because once emitted, the photon travels again at C until it hits another atom. But the delay...that is not an illusion.

What really gets weird is when the "stop" light. Check out this mind bending statement from the IO9 article

• When scientists stop light, they aren't actually halting a photon – they're embedding its quantum state into the nearby atoms. Later, they use another laser pulse to activate those atoms and make them emit an identical photon.

Other than Slow Glass what could be a use for "stopped light"? Well the ability to slow, stop and generate photons is a major step towards developing quantum computers. Of course as with any tech a criminal will find a way to co-opt it say by replacing windows with slow glass so that surveillance would be none the wiser or surveillance itself...You could be watching someone that would see nothing but a seascape say...for years....

For the complete article and reference links, check out the IO9 article HERE
Slow Light in Wikipedia HERE

Scientists photograph shortest ever "wave" of light!

What takes place in 2.5 billionth of a millionth of a second? Well among other things 2 complete waves of visible light! And now researchers at the Max Planck Institute for Quantum Optics in Garching, Germany have succeeded in capturing the shortest-ever flash of light.

<To read how they accomplished this groundbreaking feat, go to the New Scientist article>

(Thanks to Shaun A. Saunders for the post)

How To Measure the Speed of Light... Using Chocolate!

I have been a fan of the instructables web site for like forever. They are a quirky "how to" page that is part mythbusters and part demented Mr. Science. (yeah I watch way to much cable tv) by that I mean they are always building neat stuff from crap hanging around and in the process you learn some neat science!

So this week I come across how to measure the speed of light using chocolate and a microwave. Sound like BS? Nope! You take the chocolate, start warming it in the microwave, when you see melty places you stop and measure how far between the melties. Now you have the wave length. Next you have to find out the frequency of the microwave. It might be on the unit, or you might be able to look it up on the internet, if not, the instructable gives you ball parks for the average unit. Now knowing that speed is a factor of frequency and wave length times two, you simply do the math and vola!

You thought you couldn't do real science! And you get to eat your experiment!

<check out the instructable>