Archive | Physics RSS for this section

New from XKCD: What if?

XKCD is one of the best comics on the Internet. And it’s got even better! They’ve just put up a “What if” feature that they’re updating every Tuesday.

The first post is “what would happen if you could throw or hit a baseball at 90% of the speed of light”. The answer: a nuclear explosion. That’s awesome!

Advertisements

What a great birthday present – the Higgs boson!

CERN is planning to announce the possible discovery of the Higgs boson tomorrow – which also happens to be my birthday. What a coincidence! 😀

There’s a good summary of what the Higgs boson is here. Now, CERN have mentioned that they’ve seen something that is consistent with the Higgs boson, no the boson itself. However, they’re combining the results from two experiments that were within 4-sigma (i.e. four standard deviations away from the expected value, or a 1 in 16,000 chance of the results being a statistical fluke) to try and get 5 sigma, which means there is less than a 1 in 1.7 million chance of a fluke.

Either way, watch this space!

Full results breakdown

Well, I got my results an hour ago, and I definitely hold a 2.1 honours degree (if only by the skin of my teeth)!

The results are as follows, from lowest to highest, with the marks out of 100:

Optoelectronics: 25
Solid State Physics: 28
Nanotechnology: 55
Digital Signals and Image Processing: 58
Problem Solving: 59
Applied Optics: 63
Project and Laboratories: 67
Electromagnetism and Special Relativity: 78
Quantum Mechanics: 73
Atmospheric Physics: 85

What really surprised me was that Problem Solving didn’t go quite as well as I had thought, and the very high ones are much higher than I expected. What’s particularly interesting is that QM and EM are both more abstract topics, and yet I did better in them than I did in the more practical courses for Signals and Nanotechnology. As for Optoelectronics and Solid State…I fucked up in the exams for those two, and suffered a memory block in Optoelectronics.

Still, the average works out as 61.63 for this year. That makes up 80% of the degree, and the other 20% comes from the results for 3rd Year (55.5%), so the degree is 60.4% – see what I mean when I said “by the skin of my teeth”? But regardless, it’s time to celebrate!

Another use for black holes

As particle detectors, according to scientists from the Vienna University of Technology.

The basic idea is that it uses hypothetical particles known as axions; by hypothetical, I mean “not proven to exist yet”. They have a very low mass, currently predicted to be about 10^-6 to 1 eV/c^2, which in kg translates as 1.78*10^-42 to 1.78*10^-36 kg – still not low enough to be considered “negligible” in physics! By Einstein’s famous equation E = mc^2, this means it would take a relatively low (pun not intended) amount of energy to produce one, between 10^-6 and 1 eV – between 1.6*10^-25 and 1.6*10^-19 joules.

One of the fundamentals of quantum mechanics is that particles also have wave-like properties; the relationship between a particle’s energy and its wavelength is E = hc/λ, where h is Planck’s constant, c is the speed of light in a vacumn, and λ is the wavelength. from this, you can see that the wavelength is inversely proportional to the energy required, and since this is quite low for an axion, they would have very long wavelengths – if my calculations for those energy ranges are correct, they could range between 1 metre and 800 km.

Because axions are hypothesised to be electrically neutral, they would interact with a black hole through a gravitational attraction; and since they are bosons, they can be in the same state at the same time. The idea is that this creates a cloud of bosons, which can in turn create a nova that generates gravitational waves.

So, using hypothetical particles to detect and potentially prove the existence of hypothetical waves. If it works out, I suspect a Nobel Prize will be going their way!

A real “Sonic Screwdriver”

It looks like a group of physicists have taken inspiration from Doctor Who and created a “sonic screwdriver”. How cool is that? So far, it has managed to lift a rubber disk using ultrasound, which isn’t quite as good as The Doctor, but he IS about 900-odd years old!

The Dundee researchers used energy from an ultrasound array to form a beam that can both carry momentum to push away an object in its path and, by using a beam shaped like a helix or vortex, cause the object to rotate.

Now, that sounds pretty cool as it is, but what makes it even more interesting is the potential medical applications using ultrasound. Ultrasound is already used, for example, to deliver chemotherapy into brain cancer cells, or in dentistry for cleaning teeth. The head of the group that made this screwdriver claims it could be used for even more targeted delivery or precise cellular manipulation.

I bet The Doctor would be interested.

Possible evidence for particles that are their own antiparticles has been found.

Okay, why is that interesting? Well, every elemental particle has a corresponding antiparticle, which is almost exactly the same but has an opposite charge: such as an electron (negatively charged) and a positron (positively charged). Majorana fermions were predicted back in 1937 by Ettore Majorana, and if they exist they may be useful in creating quauntum computers.

To create a device that would have both the right material and a means of measuring Majorana fermions, the team connected an indium antimonide nanowire in between an electrode made of gold and the end of a superconducting material. They then placed the result onto a silicon substrate which had been preprinted with logic circuits to allow for reading the electronic properties of the nanowire. With the stage set, the team then cooled the device to just fractions of degrees above absolute zero and then introduced a magnetic field at one point and additional current at another. In both instances, the researchers found that at two points along the wire, their device registered a strong response at just the places where Majorana fermions were predicted to occur. The responses in effect showed that the particles didn’t move when in the presence of a magnetic field or an electric current, because they are electrically neutral.

Granted, it isn’t confirmed yet, but it matches the theoretical predictions so far. And even if it doesn’t actually end up being much use, it’s still a discovery!

Head of OPERA has resigned

From the Beeb: the head of the OPERA experiment, which caused that flurry over some neutrinos apparently travelling faster than the speed of light, has resigned.

Just a recap on what the whole thing was about: the OPERA experiment was (and still is) a collaboration between the Gran Sasso laboratory in Italy and CERN to detect neutrinos. However, they noticed that the neutrinos were arriving earlier than they should – by about 60 nanoseconds, or 0.000000060 seconds. Which meant they were travelling about 0.0025% faster than the speed of light in a vacuum.

Of course, EVERYONE got really excited about it, even though most physicists were sceptical. I was too. It turned out that a wire hadn’t been plugged in correctly, something that just about anyone could do. Since the ICARUS group tested this and found no discrepancy at all, the whole thing has died down.

And now, the head of the experiment is resigning. There is no statement as to why, but why? Maybe he’s just worn out after it all. It might be that they need a scapegoat – but I have no idea why. Everyone makes mistakes, and the whole thing made a perfect example of the scientific method at work. For that reason alone, I’m not going to forget about it.