High Energy Physics - Supersymmetry, Mini Black Holes, Higher Dimensions & More!

[IcyFox]

In recent weeks you might have seen news like this:

Faster than light particles found, claim scientists (Guardian)
http://www.guardian.co.uk/science/20...nos?intcmp=239

Speed-of-light results under scrutiny at Cern (BBC)
http://www.bbc.co.uk/news/science-environment-15017484

Naughty 'Faster Than Light' Neutrinos a Reality? (Discovery)
http://news.discovery.com/space/real...to-110924.html


And what reportedly happened was that neutrinos (ghostly elementary particles usually produced in weak nuclear decays) sent in a beam from the LHC in Switzerland to the OPERA detector in Italy 732km away arrived 60 nanoseconds faster than light would in the same distance.

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Why this is significant

If this is true, that particles can travel faster than light, then Einstein would be wrong and the foundations of physics would be overturned.

This would imply, among other things, that
1. Time travel is possible (as effects can come before causes)
2. Space travel is possible (both trans- and inter-galactic space flight)


Caution is advised

Discounting the possible trivial errors (because those physicists have been getting this result for months already, and have been checking and re-checking for obvious mistakes right from the beginning, so it's unlikely that they missed any such simple blunders), we still shouldn't be too quick to jump to conclusions.

For one thing, other particles, when accelerated towards the speed of light, will actually increase in mass. For example, the protons accelerated at the LHC at maximum energy will be 7,000 times their original mass when at rest. But these neutrinos, even though they are not massless (like light itself) did not exhibit this kind of mass increase and subsequent radiation.

For example: http://blogs.scientificamerican.com/...-out-en-route/

For another, there are so many other less-obvious and subtle possibilities. Maybe there's something up with GPS coordinates at this level of precision required. Maybe there's some little-understood effects that impede radio wave transmission between the 2 facilities. Maybe there's some material in the ground that can accelerate the neutrinos in unexpected ways.

Of course, all of these could be wrong, but the point is, as Carl Sagan loved to say, "Extraordinary claims require extraordinary evidence".


Some comments I would add

However this turns out, we would definitely learn something new about the world around us. In a way science is exciting because anyone can and do make phenomenal discoveries anytime, so if everything turned out just as expected, it would also be disappointing because this means there is nothing new left to learn about our Universe.

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Neutrino tracks

And the results of this experiment is definitely very unexpected. For most of us in this field, our attention was focused exclusively on the LHC itself (including me), but while the stuff we expect like supersymmetric particles fail to show up, mind-boggling results showed up at an experiment not even designed to look for faster-than-light particles. So it's kinda like everyone looks at the stage but the magician shows up and does a brilliant trick behind the audience.

Unfortunately, it would be difficult to verify the results in the near future, because there are only 2 other existing facilities in the world that can handle this - the Japanese facility was damaged by the recent tsunami disaster, while the US facility is experiencing financial hardship and have shut down their main accelerator just this week.


So, we eagerly await both theoretical and experimental solutions.



NOTE: The original pre-publication paper describing the experiment can be found here: http://arxiv.org/abs/1109.4897

[Banh Mi]

Wow, exciting news.

[Banh Mi]

Please tell us more about the Higgs Boson, and anything this video might not have covered. Must be an exciting time.

http://www.guardian.co.uk/science/vi...=FBCNETTXT9038

[IcyFox]

Hahaha hi. Yep I was pretty busy recently, so I haven't been posting news updates in this thread.

To explain what the Higgs boson is and what it does, it might be better to put things in perspective first, and since I've written a reply to a friend on essentially the same topic, I shall just be lazy and copy my reply over here.

Feel free to ask any questions if anything isn't clear.

------

We know that elements are made up of atoms, and atoms are made up of protons, electrons & neutrons; e.g. gold has 79 protons, 79 electrons & 118 neutrons.

Then we find out that protons and neutrons are not elementary, and they are made up of quarks - a proton has 2 up quarks & 1 down quark, while a neutron has 2 down & 1 up. The electron seems to be elementary so far, but has much heavier cousins - the muon and the tauon.

So far so good, but that only tells us the composition, and not their interactions. E.g. of a simple interaction ~ electron repels electron, but how? It turns out that they are actually exchanging photons, which is light, because this "like-charges repel" rule is controlled by electromagnetic interactions, and light is an electromagnetic wave.

But like charges repel, while protons can sit peacefully with other protons in the nucleus even though they are all positively-charged, why is that so? Because there are nuclear interactions between them as well, and at very short distances the nuclear interaction is very very much stronger than the electromagnetic interaction.

(But too many protons together and they are spread too far for the nuclear force to hold them together, so they break off, which we observe as alpha radiation.)

Hence we classify the known particles according to 2 categories - composition particle & interaction particle. Composition can be subdivided into 2 groups - leptons for the electron-like family, and bayrons for the quark family. Interaction include the strong nuclear interaction just described (gluon), photon, W & Z bosons (not described here) and gravitons (believed to exist but not detected yet). This collection of stuff, we call it the Standard Model:

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NOW, we are ready to talk about the Higgs boson.

The big question we've been trying to answer for a really long time now, until Wednesday, was where do the particles get their mass? The gluon & photon are massless, the electron is pretty light (neutrinos are even lighter but let's gloss over that for now), the muon is ~200x the mass of the electron, the proton is ~1800x the electron, etc.

If all the particles are symmetrical, then all the particles should be massless like the photon, which means that the electrons, protons and everyone else has to fly through space and time at the speed of light. But that's not what we see in real life. Where is the problem?

The problem lies in the fact that reality has what we call spontaneous-symmetry breaking (SSB), which means that shortly after the beginning of our universe, this symmetry in massless-ness was broken spontaneously (meaning no one went to ji seow it, it just happened on its own). And one of the models of this SSB suggested was the Higgs boson - which Peter Higgs came up with > 50 years ago.

------

From here it's pretty much continuable in the video which you posted, so there you have the basic ideas of how the Higgs boson came into the picture.

[Banh Mi]

This is great. Do tell more when you get the chance or as new information comes up. Have to get more people participating, this is the best thread at SPCnet.

[IcyFox]

Just for fun. See how many references you can catch.

http://www.naturalnews.com/036374_hi...ight_loss.html

[jadebunny9]

Wish I could like all your posts in this thread. Very exciting! Thanks for the explanations!

[Bai Qi44]

In recent weeks you might have seen news like this:

Faster than light particles found, claim scientists (Guardian)
http://www.guardian.co.uk/science/20...nos?intcmp=239

No such thing. Or, at least it hasn't been discovered yet (might never be discovered if nothing is faster than light). Anyway Icyfox (long time no chat), maybe you should edit that link out as it was a testing error (they forgot to account for relativity) that lead to the "faster than light particles".

[IcyFox]

No such thing. Or, at least it hasn't been discovered yet (might never be discovered if nothing is faster than light). Anyway Icyfox (long time no chat), maybe you should edit that link out as it was a testing error (they forgot to account for relativity) that lead to the "faster than light particles".

Oh yes, the neutrino story; I forgot to update about it.

In short, the OPERA team was the one that made the mistake, but the mistake is NOT due to omitting relativistic effects. In fact, if you actually read their original paper and watched their 1st seminar Q&A, they even accounted for subtle effects in general relativity that not many people even thought of, like gravitational time dilation. (Personally, I would even add that the paper contending that the anomaly could be explained by relativity was rubbish.)

Check out Bad Astronomy's old blog post about this:
http://blogs.discovermagazine.com/ba...so-fast-folks/

So how do we figure out who made the mistake, and what the mistake was?

In hindsight, it was quite simple (as it is with everything). Other teams performed their own experiments to measure the neutrinos' time of flight using different methods, but all got timings consistent with the speed of light, hence waving the red flag for the OPERA result. Furthermore, OPERA itself re-checked its experiment all over again, and found a serious instrumental flaw - a faulty fibre-optics connection. So at the end of the day, the mystery is solved and case closed. Neutrinos do not travel faster than the speed of light (for now at least, but maybe they never will).

http://press.web.cern.ch/press/press.../pr19.11e.html

http://www.nature.com/news/2011/1110....2011.605.html

http://www.nature.com/news/timing-gl...-claim-1.10123


Anyhow, I don't think it's a good idea to remove the previous links. I think it is only when we fully disclose our mistakes and our solutions to correct these mistakes that the public can have confidence in the scientific method. If people were to learn about science from textbooks where they polish and clean up everything to give you only the correct answers, then science would be no different from another book of blind dogmas, whether they are really true or not.

Therefore I think despite all the negativity (or probably even because of it) that this whole episode serves as an ideal case study for anyone wanting to know how real science is actually done.

[Bai Qi44]

True that. That's why I love science and hate all religions. Science will update/correct its errors when/if it's discovered. Religion doesn't do that. Science uses tests with repeatable results whereas religion.... well, you get the point. Anyway, my bad on the relativity causing error part.

Btw, when I was in elementary school, so many years ago, my science teacher taught me there were 16 moons around Jupiter (as stated in the texts of that time). Last I checked, there were 64 moons around Jupiter and counting. That's kind of like the point you made above with mistakes.

Also, a personal beef of mine is why so many people wanted Pluto to be called a planet when Charon's pretty much the same thing. Charon might be classified as a moon of Pluto, but it's not really a moon. They orbit each other and are more like twin dwarf planets then like the Earth/Moon relationship. Not to mention, there can be literally billions of Pluto like objects in the Oort cloud.