The Official Cricketweb Science Thread!

[PhoenixFire]

I was trying to explain to my Dad today what E=MC^2 actually meant, but soon realised that I didn't actually know enough about it to explain it in a reasonable manner. Could someone (SS/Spark most likely) explain what it actually means.

[silentstriker]

At it's very basic level, e=mc^2 just shows that when you measure the mass of something, you are in fact measuring its energy and vice versa.

So all energy has mass, and all mass has energy and you can convert between them using this formula.

The relationship is simple and while others had postulated some link between the two before, it's not an obvious one (e.g why it should necessarily be so).

(You may ask about photons not having any mass but yet having energy, but then e^2= p^2*c^2 + m^2*c^4 doesn't have the same ring ).

[Agent Nationaux]

Thanks for the explanation SS.

[Spark]

Optical Quantum Memory
To store a quantum state of light, you have to somehow catch it and release it, but never measure it. This is because any measurement will disturb the quantum state, thus making the memory noisy. We do experiments that aim to perfect a quantum memory that works by absorbing pulses of light in an atomic gas. At some controllable time later, we can un-absorb the light to release the stored quantum state. The are numerous projects available working on both hot and cold atomic gases, generating entangled quantum states of light, as well as theoretical modelling of the system.

Looks like fun.

[Howe_zat]

Like playing Grandma's Footsteps with photons.

[Quaggas]

Originally Posted by PhoenixFire

I was trying to explain to my Dad today what E=MC^2 actually meant, but soon realised that I didn't actually know enough about it to explain it in a reasonable manner. Could someone (SS/Spark most likely) explain what it actually means.

The principle of relativity/constancy of the speed of light (that's the crazy part) has odd consequences for the energy of light as viewed in different inertial reference frames. The connection to mass comes from looking at the change in energy of a stationary vs moving particle before and after emitting said light.

Deatils were originally written up by some patent clerk in Bern.

[silentstriker]

Hitches blamed over CERN's 'faster-than-light' claim - Yahoo! News

[Quaggas]

lol, $2 cable from radio shack. I guess they'll never want to work in this town again.

[Flem274*]

New Ultradense Planet Found; Astronomers Baffled

[nightprowler10]

Originally Posted by Flem274*

New Ultradense Planet Found; Astronomers Baffled

Or as WASP-17b likes to call it, bizarro world.

[Samuel_Vimes]

Originally Posted by Flem274*

New Ultradense Planet Found; Astronomers Baffled

The word 'baffled' is usually a good sign of bogus science news.

[Flem274*]

So I learned today from a friend whose parents work in Natural Science at our uni that the professor who takes one of our papers has some fringe religious beliefs, like the earth is 600 years old (figure quoted from person in the know, but they probably meant 6000 since it fits in with creationism) and all that.

Cue awkward moment when he says in class today "A few centuries ago, fossils and fluvial deposits were explained away as remnants of Noah's Flood," laughing as though he found the idea ludicrous. Some awkward glances were exchanged between me and some mates.

This guy is a river geomorphologist. I have no idea how he can reconcile what he researches with his religious beliefs. I mean sure rivers aren't as challenging to his beliefs as say, the fossil record, but he's published papers on reconstructing where ancient rivers and estuaries were located and what they may have looked like.

Anyone ran into similar people?

[silentstriker]

I have never met a young earth creationist in academia.

[Quaggas]

People saying one thing, but (secretly) believing something else? Unheard of.

Seriously, perhaps he was playing the devil's advocate for creationism? I've had a borderline right-wing nationalist very successfully argue the case for Marx et al, for example.

[8ankitj]

BBC News - 'Twisted' waves could boost capacity of wi-fi and TV

I didn't fully follow the physics behind it but it sounds revolutionary. I studied telecommunications long ago and it seems to challenge its fundamentals. Can someone explain what's happening here?