Tuesday, December 29, 2015

Light speed

Often it's said that Relativity doesn't allow any information to travel faster than the speed of light.

That's exaggerate and not true.

It's been shown that quantum entanglement allows information to travel faster than the speed of light. If a system is entangled, meaning it's a superposition of two states, when an interaction causes the system to fall into one of those two states, that happens instantly everywhere irrespective of how big the system is.

So, for example, if two photons get entangled and then one of them is sent to a nearby galaxy, afterwards the system comprising the two photons stretches from our galaxy to the nearby one, and, irrespective of that, an interaction with the local photon can cause an instant change in the distant one located in the another galaxy.

So information can move instantly whatever the distance.

I think, but I'm not going to prove it, that the limitation due to the speed of light regards only energy and momentum, not information.

That is not surprising, because it can be shown that the fact the laws of physics are the same everywhere causes energy and momentum to be conserved during the evolution of a system. So energy and momentum are deeply connected with the structure and geometry of spacetime, in a way that their transfer is subject to the geometrical laws of spacetime (of which the speed of light is just an aspect).

Information instead, and who knows what else, can move instantly.

In the above example, sending the photon to the nearby galaxy is a transfer of energy, that's why it's subject to the speed of light limit. But once energy is in place, that limit doesn't apply to information transfer.

So, if I may end on a sci-fi note, one may imagine harvesting photons entangled from the beginning of the universe to send information instantly to every corner of it.

Tuesday, April 7, 2015

New Horizons getting to Pluto

The New Horizons spacecraft will get to the Pluto-Charon system next July. How does Pluto and the Sun look from Charon? I tried to picture it using Celestia:

For comparison, here's how the Earth and the Sun look from the Moon:

So from Charon Pluto looks quite bigger than the Earth from the Moon, and it must be quite a spectacle. The Sun instead looks not much larger than a pin from Pluto. From the Moon it isn't so big either. In fact as it is well known it's about half a degree in angular size, the same angular size as the light disc a few millimeters across in the picture above seen from a few decimeters far.

I personally perceive the the Sun much bigger than this, but it must be just a psychological illusion.

Wednesday, March 18, 2015


I'm very fond of Lucio Battisti last records.  I think they mark the greatest achievement
in his musical career.

I was curious about the creative process behind these songs. We know pretty well how Lucio worked with Pasquale Panella. In the last records the lyrics were composed before the music.

Instead, we know less about how the songs came to take the form we can listen to now. So, I tried to ask Robyn Smith, who arranged "Don Giovanni" and "L'Apparenza" and he was so kind to reply:

Ciao Carlo, 

I have not listened to the album for a while now. I just did - oh, it is so magical. The harmonies are mainly all Lucio’s. He demoed the songs with a very simple keyboard with his voice. What was so wonderful was that he just let me arrange everything as I wanted and he seemed to like everything. 

The relationship of the sound and the atmosphere relevant to the lyrics and the meaning was most important. At that time drum machines were widely used and the use of rhythmic keyboards gave it this feeling of almost unemotion. This is what he wanted - the empty change… the appearance. 

It was so easy and so enjoyable to make. I had already arranged Don Giovanni so I knew how Lucio worked and he knew how I worked. It was great and he is greatly missed.

Many thanks for bringing back such wonderful memories.