Slashdot Mirror
Scientists Create New "Lightsaber-Like" Form of Matter
First time accepted submitter loftarasa writes "A group of scientists led by Harvard Professor of Physics Mikhail Lukin and MIT Professor of Physics Vladan Vuletic have developed a form of matter by binding massless photons together in a special kind of medium to create 'photonic molecules', effectively bringing us a bit closer to a world with lightsabers. 'The discovery, Lukin said, runs contrary to decades of accepted wisdom about the nature of light. Photons have long been described as massless particles which don't interact with each other – shine two laser beams at each other, he said, and they simply pass through one another. "Photonic molecules," however, behave less like traditional lasers and more like something you might find in science fiction – the light saber.' The work is described in Nature (paywalled)."
Because it turns out you don't need mass to be affected by gravity.
A smart guy called Einstein did a lot of explaining about this.
Physicists - please cover your ears, I'm trying to simplify.
When particle move near the speed of light their mass increases. At the speed of light it becomes infinite. Imagine a very light particle, moving very fast. By making it move near C I can get any mass I want. So now imagine i make the original particle lighter, an keep moving it faster in such a way that its moving mass stays the same. In the limit a particle with zero mass moving at the speed of light can have some moving mass. That is how a photon works.
Gravity will bend light, but the effect is very weak because light is moving very quickly. Gravity around a black hole is so strong that it will stop even light.
Real relativity and general relativity changes this a little, but the basic idea is the same. Photons are very light -> massless. They move very fast -> speed of light, so they have mass from their motion. Gravity doesn't bend light much - but black holes have very strong gravity so they do bend light.
From what I can tell, they are simply creating a system of quantum-mechanically entangled photons, not a "molecule" of photons...
You can stop reading the summary after "A group of scientists led by Harvard Professor of Physics Mikhail Lukin and MIT Professor of Physics Vladan Vuletic..." Everything after that is complete fabrication.
The only thing worse than a Democrat is a Republican.
No, photons do NOT have mass. You can only go at the speed of light (photon is light) if you do not have mass.
Photons have only energy associated with their speed. But NO energy associated with any mass.
And you do not need mass to be affected by gravity. Gravity is a distortion of space, and therefore everything in space (with mass and without) is affected by gravity.
This blog post explains everything in detail in a simple way:
http://profmattstrassler.com/articles-and-posts/particle-physics-basics/mass-energy-matter-etc/more-on-mass/the-two-definitions-of-mass-and-why-i-use-only-one/]