New Scientist reports on an intelligent paint which turns roads pink in icy conditions.

The varnish is made of a polymer containing a thermochromic pigment. The same type of coating is already used to make bath thermometers and frozen food packaging that responds to temperature change. However, it is the first time such a coating has been used to monitor road temperatures.

…

the normally transparent varnish turned dark pink when temperatures dropped below 1 °C. When the temperature rose back above 2 °C, the coating became colourless again.

Sounds like a really cool innovation. They’re currently working on it to make sure that it also has some night visibility and won’t break when exposed to high levels of UV light during the summer months.

According to the driving theory test/highway code, the stopping distance at 70mph is 96m. In ice, you need to allow 10x a greater distance. That means the stopping distance at 70mph in ice is 960m… almost a 1km. I didn’t believe it when I first heard it.

My friend sent me an article from MSNBC about how Fermilab and CERN are being sued for putting the entire planet at risk from mini black holes and other phenomena by building the Large Hadron Collider (LHC). I thought this article was a joke but it seems to be deadly serious.
For those non-physicists among us, the LHC is a new particle accelerator currently being built in Geneva, Switzerland. It will accelerate the basic fundamental particles of the universe to high speeds and smash them together with the aim of finding out what they are made from and learning more about the birth of the universe.

People have made all kinds of wild speculation about the LHC. The New Scientist published an article earlier this year musing on the possibility of the LHC being a time machine.

I think it would be true to say that scientists can’t say the LHC won’t produce a black hole which would gobble us all up because of their incomplete knowledge of particle physics – it’s this lack of knowledge which is leading them to build the LHC. But I don’t think the risks of the LHC are really significantly large enough to stop them from opening the LHC.

I’m reading a really interesting book about psychology at the moment.

In one study, volunteers were told they won a free dinner at a fabulous French restaurant and were asked when they would like to eat it. They could perhaps go now, tonight, tomorrow or to put it off to a later date. Most people put it off to a week later.

Now I’m not privy to the exact details of the study, but the book argues that most people will chose this option because they get seven days to look forward to the meal (and hence gaining pleasure from looking forward to it) as well as the enjoyment from consuming the meal.  “Forestalling pleasure is an inventive technique for getting double the juice from half the fruit. Indeed, some events are more pleasurable to imagine than to experience”.

It goes on to talk about why we anticipate the future: how it doubles the pleasure of enjoyable events and how it can minimise the impact of disappointing outcomes. Human beings, the book argues, are the only species to think about and to anticipate the future.

I might make another few posts on this book but in the mean time, I really recommend it if you’re interested in this kind of stuff.

A little post about Einstein’s theories of relativity.

Special Relativity

With Special Relativity, Einstein updated the laws for motion which were set out by Newton, the laws that we learn today in maths lessons.

Einstein’s special relativity said that we are all moving at the speed of light, all of the time. There are of course the 3 dimensions of space and 1 dimension of time. At the moment you’re probably sitting on a chair in front of a computer, and unless you are one of those people who swing your chair from side to side, you’ll be stationary.

Time Travel is possible!

According to Einstein, that means you are moving through time, at the speed of light. It’s difficult to imagine that because we don’t experience the dimension of time like we do with space.

Imagine you were moving at half the speed of light – your speed of movement through the dimension of time will actually be the remaining half the speed of light. Time is not a constant!

An real-world analogy with a bike

We can try to explain the above behaviour using some trigonometry – imagine somebody on their bike, riding northwards at 5mph. If we resolve their motion in the northerly direction, they move at 5mph; in the easterly direction they move at 0mph.

Now imagine they were moving North East at 5mph. If we resolve their movement in the North direction, it could be 3mph, in the East Direction it could be 4mph. The bike still moves at 5mph, but because some of the motion is now directed in the East direction, it moves more slowly through the North direction.

General Relativity

A few years after his theory of special relativity, Einstein came up with general relativity. This was a theory of relativity which also took gravity into account.

Imagine you are sitting on a Boeing 747, cruising at 570mph. Aside from looking through the windows and occasionally feeling turbulence, you can’t actually tell that you’re moving. I suppose what Einstein said was that you could claim that actually the whole world was revolving around you, and that would be a perfectly valid thing to say.

But when you feel turbulence, you know your definitely moving. You can feel it. Similarly when your taking off – you couldn’t claim that you were stationary. You feel the g-forces pushing you into the back of the seat.

You can feel accelerated motion and accelerated motion will influence the laws of physics and the behaviour around you. However, once you are moving at a constant speed, the laws of physics are exactly identical to if you were totally stationary.

Gravity

With general relativity, Einstein combined gravity and relativity. He said that gravity is the exact same thing as accelerated motion. We feel our weight on the ground is because gravity is pulling us towards the Earth. That’s the same thing as acceleration, thus why we can have zero-g flights in the sky.

When a plane is in freefall and moving at it’s terminal velocity, air resistance upwards is equal to gravity downwards. The resultant force is zero, so you feel weightless.

Newton and the Apple

We have already said that anybody moving at a constant velocity can claim they are stationary, and the laws of physics will back them up.

Objects which are accelerating or under the influence of gravity cannot.

With general relativity, Einstein dismissed the idea of an absolute space or absolute time. They’re both relative. We can move through space at different velocities or through time at a different speed, and observe that everybody else is moving relative to us.

However, he also introduced absolute spacetime. If an object moves at constant velocity without acceleration or gravity, that object can claim that it is stationary.

So lets go back to Newton, and the infamous apple which struck him on the head. Newton feels the force of gravity, so he cannot claim that he is stationary. The apple, however, is in freefall. Assuming it reaches terminal velocity, the apple can claim it is stationary.

What does this mean? No, the apple did not fall and hit Newton on his head. In fact, it was Newton’s head which rose and struck the apple!

It was, of course, the lunar eclipse last night. I took some pictures at 5 minute intervals and created an animated gif out of them.

See larger version of animation. 

The first frame was taken at 9:53 PM GMT and the last at 10:33 PM GMT.

Taken using a handheld "point and shoot" Canon camera at 4x optical zoom so the quality isn’t too good, but I still think it’s pretty cool nonetheless.

I’m not sure why but the moon actually appeared blue around 10:18. The animation actually shows the moon becomes yellow, then blue, followed by red. Images were taken on a 1/350 exposure. 

Anyone else go out to see the eclipse?