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07-04-2012, 07:59 PM   #76
Pooh-Bah

Join Date: Jun 2009
Posts: 5,832
Re: LHC Higgs Boson Search Update

Quote:
 Originally Posted by NoahSD What does this interaction do?

Quote:
 How does the top quark interacting with the Higgs field really really often lead to it being harder to push the top quark?
Well, "harder to push" means you need more energy input to get the same velocity increase. In other words, a larger mass means the same kinetic energy change results in a lower velocity change. You can see this in the formula E = mc^2 + 1/2 mv^2 + ...

So your question boils down to: why is the above formula correct, i.e. why is kinetic energy proportional to mass? or, why is mass proportional to momentum?

I'm not entirely sure how to answer that, but I'll have a go:

The top quark has an energy it gets from the Higgs field of 173 GeV (i.e. that's its mass). If an observer measures the energy of a top quark and finds 174 GeV, it would mean that there is 1 GeV of kinetic energy, i.e. they would reckon the velocity to be 1/sqrt(174), in the appropriate units.

If an observer measures the energy of a proton (mass 1GeV) and finds 2 GeV, there's still 1 GeV of kinetic energy, but now the measured velocity would be 1/sqrt(1) , much faster than the top quark for the same energy change.

 07-05-2012, 03:03 AM #77 old hand     Join Date: Feb 2010 Location: New Delhi, India Posts: 1,637 Re: LHC Higgs Boson Search Update I think for anyone who wants to understand the bigger picture through particle physics it is important to do the following before imagining what is happening: 1. Get a good grasp of the double slit experiment 2. Understand the massive difference between wavelengths of electrons and size of a nucleus and the size and emptiness of any atom. 3. Understand what Pauli's exclusion principal is saying and how it explains why the universe has a structure 4. Heisenberg's uncertainty principal and it's implications on how there is a probability that any matter can jump from one point in space to another pretty much instantly. 5. Richard Feynman's QED Here are two documentaries that cover these topics pretty well in layman terms: ATOMS http://documentaryheaven.com/pt-13-a...of-the-titans/ http://documentaryheaven.com/pt-23-a...to-the-cosmos/ http://documentaryheaven.com/pt-33-a...on-of-reality/ BRIAN COX'S A NIGHT WITH THE STARS http://documentaryheaven.com/profess...ith-the-stars/
07-05-2012, 05:56 PM   #78

Join Date: May 2011
Posts: 2,605
Re: LHC Higgs Boson Search Update

Quote:
 Originally Posted by t_roy My understanding is that this thing gives some particles mass but not that is responsible for all of our (humans) mass correct?
Most mass in large composite systems, like humans, is due to bonding energy

07-05-2012, 07:47 PM   #79
old hand

Join Date: May 2012
Posts: 1,419
Re: LHC Higgs Boson Search Update

Quote:
 Originally Posted by t_roy My understanding is that this thing gives some particles mass but not that is responsible for all of our (humans) mass correct?
Yes, by far the biggest contribution to the mass of everyday objects (including humans) is QCD binding energy. You can go add up the masses of the quarks in a proton and see that the proton actually has a much larger mass.

07-05-2012, 09:04 PM   #80
old hand

Join Date: May 2012
Posts: 1,419
Re: LHC Higgs Boson Search Update

Quote:
 Originally Posted by NoahSD The metaphor seems to suggest that the particles are slowed down, but of course particles don't continually change velocities (at least not over large timescales where quantum fluctuations average out), and "slowed down" makes no sense without a reference frame
Massless particles must travel at the speed of light in all frames, so you can say the Higgs "slows down" the particles it gives mass to by making their velocity <c in all frames.

Quote:
 (I assume the Higgs field doesn't create a preferred frame...).
Yes, the Higgs field is a scalar field so it can have non zero vacuum expectation without creating a preferred direction/frame.

 07-05-2012, 09:13 PM #81 veteran     Join Date: Aug 2009 Location: Stanford, CA USA Posts: 3,322 Re: LHC Higgs Boson Search Update There you go for some numbers on the "mass" of large composite particles hence ultimately atoms etc; http://forumserver.twoplustwo.com/sh...9&postcount=13 "Most of atom's mass is binding interactions ("dynamic")/ kinetic energy actually between quarks that compose the protons and neutrons. Look at it this way ; Atoms are made or protons and neutrons and electrons. We know proton/neutron are not elementary but rather composite particles. A proton is a combination of 3 quarks (uud) and has energy mc^2 equivalent of 938 Mev (1.67*10^-27 kgr) Yet the so called bare mass (they cant actually exist alone free) of the u quark is around 2.5 Mev and that of d quark is 5 Mev. So basically 15 Mev is quarks and the rest to make 938 is binding energy (QCD gluon field binding energy). So basically the bare mass is only 1.6% of the total. The rest is interactions related effective energy and lets call it kinetic too (if you try to picture it semi classically as moving all over the place within a diameter of less than 10^-15 m). (similarly for neutron) . The electron is also small 0.512 Mev. My point is the bare mass of all the "elementary parts" that make a simple atom is only a supertiny fraction of the observed total." Also as to how the fermion mass is generated via Higgs mechanism ; http://en.wikipedia.org/wiki/Spontan...metry_breaking http://en.wikipedia.org/wiki/Higgs_mechanism (section consequences for fermions) http://en.wikipedia.org/wiki/Electroweak_interaction (section on Lagrangian) http://en.wikipedia.org/wiki/Yukawa_interaction
07-05-2012, 09:18 PM   #82
Pooh-Bah

Join Date: Jun 2009
Posts: 5,832
Re: LHC Higgs Boson Search Update

Quote:
 Originally Posted by SenseiSingh I think for anyone who wants to understand the bigger picture through particle physics it is important to do the following before imagining what is happening: 1. Get a good grasp of the double slit experiment 2. Understand the massive difference between wavelengths of electrons and size of a nucleus and the size and emptiness of any atom. 3. Understand what Pauli's exclusion principal is saying and how it explains why the universe has a structure 4. Heisenberg's uncertainty principal and it's implications on how there is a probability that any matter can jump from one point in space to another pretty much instantly. 5. Richard Feynman's QED
Kind of disagree here. You can get a reasonable understanding of quantum fields and particles without going into wavefunctions . Secondly, the usual way that your points 1-5 are presented is actually quite confusing, in attempting to 'dumb down' the topic from math to English, key principles get 'dumbed out'.

Even single-slit diffraction is not easy to understand; if you demand a list of prerequisites then the person will get lost before they catch a glimpse of the bigger picture.

I'd strongly recommend reading all of the articles on profmattstrassler.com, superb writing style for non-mathematicians; and also all of the Feynman diagram articles on Flip Tanedo's blog.

 07-05-2012, 09:24 PM #83 Pooh-Bah   Join Date: Jun 2009 Posts: 5,832 Re: LHC Higgs Boson Search Update Also think all the Wikipedia articles on particle physics are very poor for laymen.
 07-05-2012, 09:54 PM #84 Is Right     Join Date: Aug 2005 Posts: 18,795 Re: LHC Higgs Boson Search Update Ohhh. I gives mass to particles the same way that gluons give mass to quarks in a proton. That makes sense. Ty!
07-05-2012, 10:12 PM   #85
veteran

Join Date: Aug 2009
Location: Stanford, CA USA
Posts: 3,322
Re: LHC Higgs Boson Search Update

Quote:
 Originally Posted by Kittens Also think all the Wikipedia articles on particle physics are very poor for laymen.
Thats because the layman has no place trying to understand standard model without first becoming a physicist. There i said it. That is the only truth about the matter. The layman doesnt have what it takes to ask such questions if not prepared to do what it takes to get the answers the only way that makes them worthy.

When i offer links from wikipedia i do it in the order one must read them not as much so that they understand it all (in the absence of fundamental education) but in order most importantly to understand how much they need to learn first in order to start getting clues about what is all about.The links in these topics mostly play the role of motivating one to go and read from the start and stop being lazy and ignorant thinking that suddenly some stupid documentaries of simplistic in the end popular books will give a satisfactory answer. They wont. You will just have a feeling of being religious again without coherent understanding having to dogmatically or semidogmatically "believe" what they say under the illusion that you "get it now". And that is not a way to live. At least not a satisfactory way.

I am not necessarily saying that popular science books are worthless after a certain level. But i am saying that the only kind of popular books i like to suggest to a kid or a decent well intentioned enlightened adult wishing to embark in a life long trajectory of discovery even as amateur, are the kind of books that although try to describe in simple terms what is going on offering plenty of information in as friendly terms as possible (Feynman like positive style) , at the same time suggest to the reader that the honest alternative to trusting the story presented in every section is to go out and read (or take classes) well structured ordered material that the popular book is willing to disclose in notes/references or appendices or special chapters (exactly as a mentor would do). What young and curious minds in general need is not a story that sounds convincing and is trying to offer the illusion that suddenly the secrets of nature will be revealed so easily but instead direction and well structured advice after offering the "story", about how to go and educate themselves properly in order to fully comprehend why the story makes sense and fully appreciate also its weak elements. A popular/layman style book must never remove itself from the responsibility to offer also direction to someone young or young at heart in general, who is genuinely interested, because those are the ones that most definitely celebrate with their choices, effort and curiosity the human spirit and are most in need of such help because they will put it to good use. In particular i like a story telling approach that follows the historical path of discovery in science itself. It is the most natural way to present things.

Basically what i say is simple. I find it arrogant trying to ask super deep questions with the audacious assumption that answers will be provided that will be satisfactory without doing all the middle steps work that real scientists take decades to trace. Yes i am strict like that. Its 100% more important for someone to go and read for example classical mechanics and understand Lagrangian formulation (ultimately even build yourself to understanding some quantum field theory after some electromagnetism and quantum mechanics) than having the illusion that Hawking or Greene etc will give them the answers. Without proper education you havent earned the right to ask tough questions.

So either get a subscription to scientific american etc or do the honorable thing and take some classes or read textbooks in the proper order. At least then what you learn is yours to keep forever and maybe one day can even help you understand a lot better the harder questions like your intellect fully deserves if you respect yourself when you want legitimate answers. Not everyone has the courage or time to do all this but at least they then must have the courage to recognize that some questions cannot be asked with the naive expectation that getting an answer will actually illuminate anything.

 07-05-2012, 10:13 PM #86 Pooh-Bah   Join Date: Jun 2009 Posts: 5,832 Re: LHC Higgs Boson Search Update Also, a major unsolved problem is why the Higgs field -- which has an energy of 246 GeV at every point in spacetime -- doesn't get pulled on so hard by gravity that the whole Universe rolls up into a little ball. The best explanation we have so far is that there's a counterbalancing expansion force that almost exactly counters the energy in the Higgs field (and the QCD vacuum while we're at it). Obviously this is far from satisfactory
07-05-2012, 10:23 PM   #87
Pooh-Bah

Join Date: Jun 2009
Posts: 5,832
Re: LHC Higgs Boson Search Update

Quote:
 Originally Posted by masque de Z Basically what i say is simple. I find it arrogant trying to ask super deep questions with the audacious assumption that answers will be provided that will be satisfactory without doing all the middle steps work that real scientists take decades to trace.
Sorry, but I have to completely disagree here. Every human being is entitled to their inquisitiveness, and I think it's great if people want to try and find answers to the mysteries of the universe. Also, what is science for if not to spread knowledge amongst the human race? You sound like a Scientologist.. only the elite may rise to the privileged level of learning the deep secrets of nature

I think posters like NoahSD are well aware that for a 100% full understanding of the topic, they would need to spend years at university. However I am glad he posts his question anyway, and I enjoy answering.

I tend to think that if you can't explain something it's a failure on your part. In fact, trying to formulate your own understanding in a way that the target audience will understand, is a great way to improve your own understanding.

For example I found some insights I didnt have before, when trying to answer Noah's question "How does the top quark interacting with the Higgs field really really often lead to it being harder to push the top quark?" . I'm still not satisfied with my answer and will be thinking about it more in future until I am happy

I had a friend who would say, "If you can't explain it to the janitor then you don't really understand it". Of course, this is not to be taken completely literally, but there is a lot of truth in it.

07-05-2012, 10:34 PM   #88
Pooh-Bah

Join Date: Jun 2009
Posts: 5,832
Re: LHC Higgs Boson Search Update

Quote:
 Originally Posted by NoahSD Ohhh. It gives mass to particles the same way that gluons give mass to quarks in a proton. That makes sense. Ty!
Hopefully you mean that energy due to interaction with the Higgs field, is like energy due to interaction with the gluon fields.

I've never actually seen a real physicist describe mass as 'interaction energy with the Higgs field', but my understanding is that that is actually correct. "Interaction energy" is a synonym for potential energy, but one that perhaps directs you towards better understanding.

There is perhaps an analogy with light traveling through other matter; light slows down in glass for example, so it could be said that the medium confers mass on the photos while the photon is in the medium.

It's been speculated that light is also slowed down by interaction with the QCD vacuum ("virtual particle pairs") in a similar way to how it is slowed down with glass, and if somehow there were no QCD, then light would move faster than its currently measured speed. Perhaps similarly to to how the 'real' charge of an electron is shielded by all the 'virtual pairs of photons' that surround it at all times. However, as far as i know there is actually no experimental support for this idea.

07-05-2012, 10:58 PM   #89
old hand

Join Date: May 2012
Posts: 1,419
Re: LHC Higgs Boson Search Update

Quote:
 Originally Posted by masque de Z Without proper education you havent earned the right to ask tough questions.
Lolz...is this serious? You never ask questions to computer scientists/mathematicians/physicists about things you know you don't have the time and background to understand fully but are curious to learn at a wikepedia level?

 07-05-2012, 11:05 PM #90 veteran     Join Date: Aug 2009 Location: Stanford, CA USA Posts: 3,322 Re: LHC Higgs Boson Search Update Oh but i am not at all pushing the layman or youngster away. I simply tell them the truth and invite them to do what it takes. I invite them to be brave. In effect i want them to trust their intellect even more than a superficial sequence of question/answer in simplistic terms will achieve (like the ones documentaries offer say or many books) . This can never be based on fairy tales. I expect the same for myself of course and those that help me. One must do both, try to explain is simple terms and yet also convey the point that these terms are still demanding of solid education up to a minimum safe point at least. One must also open the door to the one helping to see for themselves what more they need to learn. You must illuminate their path. The hardest/coldest fact one finds out in grad school and above is that nobody actually gives a damn about you building a proper hole free education which of course is what matters as a thinker!!! Which of course is also your only chance to achieve anything interesting and original. They are all about their top research papers and the hell with your "holes" in education and line of thinking. How ridiculous that say a 22 even 25 year old will be suddenly so capable to do string theory...having completely missed 60-70 years of serious QM and field theory and standard model in details that even 4-5 classes first/second year in grad school will absolutely never reach. Imagination is more important than knowledge but only someone with the education of Albert at age 26 can say that. Because potent imagination is always founded on rich knowledge. So ask yourself what his education was when he gave you Relativity (in terms of his era) and you will be shocked at how much better it is than today's 25-26 year olds in current top physics research. Ah the audacity really! Massive prevalence of "holes" in education even if out of the best schools. Last edited by masque de Z; 07-05-2012 at 11:10 PM.

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