Be Careful Waking Up a Sleeping Blog

After a very busy few months, in which a move to a new city forced me to curtail all work on this website, I’m looking to bring the blog gradually out of hibernation.  [Wordsmiths and Latinists: what is the summer equivalent?] Even so, a host of responsibilities, requirements, grant  applications, etc. will force me to ramp up the frequency of posts rather slowly.  In the meantime I will be continuing for a second year as a Visiting Scholar at the Harvard physics department, where I am doing high-energy physics research, most of it related to the Large Hadron Collider [LHC].

Although the LHC won’t start again until sometime next year (at 60% more energy per proton-proton collision than in 2012), the LHC experimenters have not been sleeping through the summer of 2014… far from it.  The rich 2011-2012 LHC data set is still being used for new particle physics measurements by ATLAS, CMS, and LHCb. These new and impressive results are mostly aimed at answering a fundamental question that faces high-energy physics today: Is the Standard Model* the full description of particle physics at the energies accessible to the LHC?  Our understanding of nature at the smallest distances, and the future direction of high-energy physics, depend crucially on the answer.  But an answer can only be obtained by searching for every imaginable chink in the Standard Model’s armor, and thus requires a great diversity of measurements. Many more years of hard and clever work lie ahead, and — at least for the time being — this blog will help you follow the story.


*The “Standard Model” is the theory — i.e., the set of mathematical equations — used to describe and predict the behavior of all the known elementary particles and forces of nature, excepting gravity. We know the Standard Model doesn’t describe everything, not only because of gravity’s absence, but because dark matter and neutrino masses aren’t included; and also the Standard Model fails to explain lots of other things, such as the overall strengths of the elementary forces, and the pattern of elementary particle types and particle masses. But its equations might be sufficient, with those caveats, to describe everything the LHC experiments can measure.  There are profound reasons that many physicists will be surprised if it does… but so far the Standard Model is working just fine, thank you.

132 responses to “Be Careful Waking Up a Sleeping Blog

  1. Aestivation.

    And nice to have you back, Professor.

  2. Beverly Capers

    So glad to see you back! Congratulations on your continuing work at Harvard! Hope to get to see you this year in Boston…… Best of everything! Beverly

  3. Welcome back professor, we missed you.

    LHC is great but there is a very interesting experiment going on at Fermilab with the Muon g-2 investigation. Been reading up on it and feel this could very well bridge the gap and potentially lead us to a unified theory. What are your thoughts?

    You probably had an article or two in mind on the muon g-2, could you please bring us up to date?

    Again, welcome back and congratulations on the Harvard move.

  4. Theo Nieuwenhuizen

    Should the LHC indeed confirm the Standard Model for all its aspects, this would be a wake up call for all those who believe that endless fantasy has a place in science. Remember that Planck had the greatest difficulty to believe quantization, he spent decades -in vain- to find other explanations. Today everybody can cook up new particle zoos, new forces, dark matters, multiverses, extra dimensions, (as) many (as you like) worlds, antropic principles (I think, therefore I “am right”).
    Imagine what the cold shower teaches us if LHC finds nothing Beyond the Standard Model. It would stem with my adagio that it is the task of physicist to explain Nature.

  5. Welcome back Matt.

    IMHO the Standard Model is nowhere near “the full description of particle physics at the energies accessible to the LHC”. For example it doesn’t properly describe gamma-gamma pair production. Take a look at two-photon physics. See how it says two photons cannot couple to one another? And that one photon fluctuates into a charged fermion–antifermion pair, to either of which the other photon can couple? That’s wrong. A 511keV photon does not spontaneously turn into a 511keV electron and a 511keV positron like worms from mud. And they do not magically turn back into a single 511keV photon which nevertheless manages to continue propagating at c. Pair production does not occur because pair production occurs! That’s a tautology. Instead there’s a photon-photon interaction. But it’s missing from the Standard Model, and there’s lot’s more things like that.

    • If W+, W-, and Z bosons could gain mass through the Higgs mechanism at high energy and causing present radioactive decay, why not at further high energies (accessible to the LHC) – the “decay” means more speed of light than “c” ?
      Creates MORE new space – MORE new space means MORE speed of light than “c” ?
      Standard Model theories hint that an extension of Salam and Weinberg’s work should be possible. At higher energies QCD should unite with QFD in much the same way that the electromagnetism unites with the weak force to create QFD. The unity may only breach “c”.

      A disaster like this is very unlikely for the time being as physicists do not have a particle accelerator large enough create such an experiment, but Prof Hawking’s comments have excited scientists, the Sunday Times reported.

  6. Richard Bauman

    Around 5 years ago Abell 520 had a lot of Dark Matter at its center. About Nov 28, 2012 a study from U. Ohio implied not so much, Would you know the current assumptions on Abell 520 ?

  7. Hi! I understand this is somewhat off-topic but I had to ask.
    Does building a well-established website like yours require
    a massive amount work? I am completely new to blogging but
    I do write in my journal on a daily basis. I’d like to start a blog so I will be able to share my personal experience and
    feelings online. Please let me know if you have any recommendations or tips for new aspiring bloggers.


  8. Well, that was a big break indeed! Nice to have you back :)

  9. Estivation is the summer equivalent of hibernation!

    Sent from my iPhone


  10. Estivation is the word you are looking for.

  11. Matt, Glad to see you back. You provide a wonderful service. Thanks for all you do.

  12. Happy awakening after hibernation, professor.
    I missed you a lot.
    My guess was that you were busy preparing your book using the material from this blog.
    In the meantime, during your hibernation some ” rumors” emerged that everything that we observe could be no more than 2D hologram if the experiment confirms that.
    Suppose it does, would it somehow affect your work and this blog ?
    Excuse me for my naïve Q.
    Your fan,

  13. Delighted to have my favorite blog back. All the best

  14. apologies for near-double post. didn’t realise that email would go straight to comments section!

    And yes indeed! Welcome back Mr. Strassler, looking forward to your usual lucid, and (almost) understandable explanations/illuminations of the world of physics. I say almost, but the lack is all mine, sad to say!

  15. Thank heavens for news concentrators; mine faithfully heralded Professor’s return. Yippee!

  16. Tony Rotz(Racz)

    You were gone? Just had to say that.

  17. So glad to see my favourite physics blog back alive! Ya-ay!
    Looking forward to new posts!

  18. Thank you professor for your belief in communication and explaining complex things into simple images..

  19. The Standard Model not describing everything makes me wonder why. It describes everything the LHC experiments can measure. I am afraid that the results of the LHC experiments are exogenous, given the enormous quantities of energy used in the LHC processes from external input. Maybe that is why the Standard Model cannot describe endogenous “things” like gravity. I am sorry if I am not careful enough.

  20. Welcome back nd thank you for your time once again, Dr Strassler !

  21. Nice to have you back! I’m afraid little has happened on the blogosphere in your absence. Planck’s polarization data should shed some light on the Bicep2 results soon though.

    So, what’s going on in the “real world”?

    The summer equivalent of hibernation is

  22. john McAllison

    Back just in time, since there’s rumours that Planck will be releasing new results that will clarify the BICEP2 results very shortly!

  23. I think that what you published made a great
    deal of sense. However, think on this, what if you added a
    little content? I ain’t saying your information is not solid,
    however what if you added a title that makes people want more?
    I mean Be Careful Waking Up a Sleeping Blog |
    Of Particular Significance is kinda boring. You might glance at Yahoo’s front page and
    see how they write article titles to get viewers to open the links.
    You might try adding a video or a picture or two to get readers interested about what
    you’ve written. Just my opinion, it would bring your blog a
    little bit more interesting.

    • Or dancing girls. Sex sells! Maybe that’s what’s needed to bring physics to the masses! You know – a little background radiation . . . a little background dancing. A discussion on string theory – a little string bikini. A discussion about how hard you’re working, mixed with a little twerking.

      OTOH, high energy physics is pretty sexy by itself. Keep up the good work.

  24. Tony Rotz(Racz)

    Sorry Mike but Physics is sexy? Well it might be interesting and fun at times, but sexy? Not quite the sexy my wife has. Maybe to some, I guess, but who are these people?

  25. 2-D Hologram? Are the new generation of physicists working in front of a monitor to much? :-)

  26. I missed your blog, and wondered what had happened to it, so I’m glad its back. Simpler than ‘estivation’ or ‘aestivation’: nap.

  27. Yippie! Welcome back, I’ve missed reading your stuff. Hope everything settles into the new city nicely and congratulations on the continuation of your Visiting Scholar-hood.

  28. Greetings Matt.
    We missssssed you.

  29. Now many claims that Gravity Probe B is a failure .. What if Gravity as curvature is refuted ?
    It is not only one question related to the SM , is it a paradigm shift in our understanding of reality ?
    Is it a fact that what we know now may be a delusion ?
    Did you read ” the science delusion ” by Dr. Sheldrake ?
    Did you read ” How Einstein ruined physics ” ? What if it is a fact ?
    I wonder !!

  30. How Einstein Ruined Physics: Motion, Symmetry, and Revolution in Science [Kindle Edition]
    Roger Schlafly (Author)
    4.3 out of 5 stars See all reviews (17 customer reviews)

    • How Einstein Ruined Physics however is not just about Einstein the man, but how the world-changing findings in physics over the past century have produced an Einstein cult that continues to impact modern science negatively. In physics, says Schlafly, this has led to wasteful, un-falsifiable “top down” theorizing that often leads nowhere.

      Einstein is the new Aristotle. Physicists love to ridicule Aristotle for his non-quantitative theory of physics, for his thought experiments, for his unsubstantiated realism, and for his (supposed) attempts to explain the world according to how he thought the world ought to be, instead of how it is. Most of all, they ridicule Aristotle followers for idolizing the master, and for blindly following what he had to say.

      Aristotle was a great genius. [Aristotle’s] reasoning was influential for well over a millennium. But Einstein’s fame is based on the work of others, and his legacy is the pursuit of unscientific dreams. Now he is idolized more than Aristotle ever was, and his followers have created a subject more sterile than millennium-old Aristotelian physics.

      Medieval monks are mocked for debating how many angels can dance on the head of a pin. They didn’t really do that, but modern theoretical physicists write papers on topics nearly as silly. They write papers on alternate universes, black hole information loss, extra dimensions, and Boltzmann brains. Most of them are preoccupied with string theory, which has no connection to the real world. And they all say they are pursuing Einstein’s dreams.

  31. 5.0 out of 5 stars Nice To Read What Most In Particle Physics All Know – Einstein Was A Fraud July 10, 2012
    By E. Baumgartner
    Excellent book. And the author’s clear, crisp writing style makes for enjoyable reading.

    Many (if not most) theoretical Physicists today know (privately) that Einstein was a fraud. It is rather common knowledge that Einstein stole ideas from other European Physicists who either preceded him or were his contemporaries. Thanks to the internet, scientific papers which Einstein “borrowed” are today widely available as PDF files, and many of these papers even being translated into multiple languages.

    The problem is that, for whatever odd reason, it is highly unfashionable to bash Einstein, hence few if any scientists do so (at least publicly). For this reason, this book was refreshing to read.

    Albert Einstein was actually a run-of-the-mill Physicist. I can easily think of twenty of his contemporaries who, sadly, get no accolades yet were far beyond Einstein in the ground breaking research they performed.

    • I posted the above just to show that physics is in deep need of re-evaluation of ” The Dream ” , physicists cannot afford to neglect the stream of opinions , I accept deeply that LHC is a great interprice for physics but many many followers do not accept the fantasies of many high caliber physicists and cosmologists ……. Remember ” The Grand Design ” ? No one in his mind would accept that Gravity IS the designer .. Period .

      • Dear Aashami, science isn’t religion or a political party, so the direction of its progress isn’t determined by what the “followers” think or accept but by scientific evidence.

        • If that were the case, then why have poorly motivated theories that have virtually no empirical support, like string/brane theory, supersymmetry, the “multiverse” fantasy, “WIMPs”, etc, been dominant in theoretical physics for 40 years?
          The sad truth is that theoretical physics has become very much like a religion, at least for a large and influential segment of that community.

        • You’re right, Lubos, it’s far beyond those time dependent notions. ;)

          • Ultimate physics – free Math. — M – whatever — for example is not healthy for physics ……. Remember : cosmology is physical not abstract unless you are an extreme platonist .

          • I understand your argument, asshami. However, what would modern day cosmology be without the “platonic” content of Riemann’s 1854 inaugeral lecture Ueber die Hypothesen, welche der Geometrie zu Grunde liegen? The transition from the abstract to the physical takes time. It always has. Be patient, as experimental confirmation of many of our cutting-edge, abstract physics will inevitably occur.

    • People always love a great story.

    • Einstein did indeed make use of Riemannian geometry for his theory of General Relativity. This only lends support to Wigner’s observations on the unreasonable effectiveness of mathematics in the natural sciences.

      The current situation, with M-theory, is much more akin to that of Newton’s times, which by necessity, spawned the “method of fluxions and fluents”, i.e. the differential calculus. Newton was 23 years old when he first made use of these (at the time) novel mathematical techniques. What is the modern day version of Newton’s method of fluxions? This new mathematics that will give us a complete theory of quantum gravity (and beyond) will surely be appreciated by future citizens, who will look back at this special time with great reverence.

  32. Agreed , I meant by followers those who follow up news of science and care about scientific representation of reality .
    Thanks Lubos .

  33. of course like your website but you have to check the spelling on quite a
    few of your posts. Several of them are rife with spelling issues and I
    find it very troublesome to inform the truth then again I will definitely come again again.

  34. Aashami,
    Your slanderous rant on Einstein is exclusively based on fabricated lies and false accusations. See for example:
    I am having a hard time believing that Prof. Strassler tolerates this kind of trashy talk on his website!

    • Why do you write to me ? Write to Dr. Roger Schlafly auther of ” how Einstein ruined physics ” .. I did not utter a letter w.r.t. Einstein , I just mentioned what researchers say , so why blame me ? ….
      The aim is to find a fresh path to reality instead of stagnation due to some dogma ………calm down .

      • aashami, when you use your voice on the internet to distribute opinions of others, it is only fair if you accept to be criticized for the selection and distribution of these opinions. (And those are not statements of researchers but the opinions of some random guys posting amazon reviews.) You pretend to have a passive role in this, but in fact you are actively propagating statements which are false and slanderous, in my opinion.

        Also note that even if all those statements about Einstein’s character and lack of integrity were true (which I’m sure they are not), this would not reduce the scientific correctness and importance of the theories of special and general relativity by the slightest amount.

    • Unfortunately, this baseless slander on the pass masters is to be expected because of the erosion of the understanding of their great contribution of laying down the foundation that supported the breakthroughs of recent years. Not sure of the cause, whether there are fewer intelligent people or more stupid people.

      Anyways, that asteroid to pass us on Sunday will be only 22,000 miles from Earth, according to NASA’s definitions that would have been classified as a hit. Not sure what to make of that? Is it a lesson for us to get better defensively or a lesson that catastrophic asteroid threats are just myths because Earth can never be hit before of the planets configurations, a plane, we can only get hit by one coming off the plane and chances or nil.

  35. “I just mentioned what researchers say , so why blame me ? ….
    The aim is to find a fresh path to reality instead of stagnation due to some dogma ………calm down .”

    These are not “researchers”, they are crackpots with a personal agenda.

    You are the one that needs to calm down, Aashami. You would be better off understanding the facts and their historical developments prior to spamming
    this blog with malicious claims.

    • Please , calm down , this is a free conversation not a dictatorship of dogma , we both care about physics as a path to reality , so all opinions are allowed .

    • Please be honest enough to read ” How Einstein ruined physics ” then face reality……….thanks

      • Aashami,

        Your vitriolic opinion about Einstein’s work is a sad reminder of German Nazi’s calling Relativity “Jewish physics”.

        This blog is no place for impostors like yourself pretending to discuss science!

        • WOW ….
          Read the book and send to the author whatever you fancy .
          Argument closed .

          • Ass-hami,
            Reading anti-semitic books or prejudiced comments from ignorant people like you is a complete waste of time!

          • Aashami, Iam not a Jew. I came from a place which did not know about Nazis or Jews or what happened at that time in Europe.
            Max Planck was told to make more light with less heat – he came up to the level of black body radiation and “non zero” value of the vacuum (space). It was out of his own religious belief to come out of dark and cold nights of that time.
            Relativity was not Jewish. It was a common sense existed at that time.
            What Einstein’s specialiy, I believe, was his “discovery” of relation between “space and speed of light c”.
            If you pull a rubber band at the speed of light, that is the maximum level that band can exist. It also have a tendency to pull back (non zero). If it exceeds “c”, this tendency is replaced by new space – to keep the “c” constant.
            Is it correct or not ?

  36. In the meantime I would ask for a wakeup call on the Rosetta measurements on Comet 67P CG, becuase:
    If Rosetta probe is able to discriminate the peculiar dark matter gravity point sources inside Comet 67P-CG, and even an intrinsic EM field, then ESA will be able to boost astro- and physics understandingabove the standard model even more than Eddington did 95 years ago ( bending of light)


  37. aashami never said that Mr. X is such or such , he was wondering if that was a fact ……..shame on attackers .

  38. aashami | September 6, 2014 at 6:38 AM | Reply
    Now many claims that Gravity Probe B is a failure .. What if Gravity as curvature is refuted ?
    It is not only one question related to the SM , is it a paradigm shift in our understanding of reality ?
    Is it a fact that what we know now may be a delusion ?
    Did you read ” the science delusion ” by Dr. Sheldrake ?
    Did you read ” How Einstein ruined physics ” ? What if it is a fact ?
    I wonder !!
    BE CAREFULLL before attacking for no reason .

  39. Instead of shameful arrogance from some , and shameful impoliteness from other , answer his questions which are in the heart of physics .
    First question is a very deep one , what if ?? Really .

  40. I would extend Dr. Strassler,s criteria :
    Where we stand if the SM proved to be incomplete with no sign of any physics beyond ?
    According to Dr. Strassler , even quantum fields may not be the most fundamental aspect of reality , what if Q.F. Proved to be only a mathematical device with no roots in reality ?
    Where we stand if dark matter proved to be non- existing , then what for cosmology ?
    Are we on the verge of really a beyond cosmophysical reality ? I mean is this a possibility ?
    Thanks Dr. Strassler .

    • Re: “what if Q.F. Proved to be only a mathematical device with no roots in reality ?”

      Quantum field theory in the form of the Standard Model (SM) is certainly an excellent description of reality at the energies that are accessible up to now. This has been proven again and again in many experiments. It has been proven to such an astonishing degree of accuracy, that some physicists are getting depressed that no deviation from the SM is seen anywhere. What a remarkable situation! I think it is very rare in science to have such an accurate and well-proven theory.

      For sure the SM is not a complete description of nature, e.g. it does not include gravity. But this does not change the fact that QFT and in particular the SM are valid and proven, and they will remain valid and highly relevant approximate descriptions of reality, no matter which kind of even better approximations will be discovered in the future.

      Think about the following: If you have a car, you probably think it is very real and you know it very well. Do you know anything about your car with an accuracy of 10 decimal places, or so? I guess not. You only know your car approximately. Still it is perfectly real, isn’t it?

      • Thanks Dr. Steiner :
        I presume that it is a good agreement among physicists that Quantum fields may not be the ultimate primary fundamental aspect of reality … then we can say , as the SM related experiments were analysed by QFT equations then the match depends on the assumption that Fields are reality , now what I mean is : suppose Fields are not the primary fundamental reality which is a valid possibility , then what would be the impact on physics ? That is the question.

  41. First can I say that I love the blog, can’t wait for the new material and goodluck in you. ventures old and new.

    If I could make one request could you do an piece on the theory holography and the interpretation string theory postulates (maldacena’s work), if there is an easier way to describe it in keeping with your blog.

    Many thanks and great to see you back Proff…… Best physics blog around :-)

  42. What if Dark Matter proved to be Multi-Component where Multi means any number from 2 to who knows what ?

    • M. Many,

      You are missing two important points in your rants:

      1) General Relativity and the Standard Model of particle physics have been confirmed by observations countless times. Both are so-called “effective” theories, likely to be amended by future experiments. Thus both theories cannot be “wrong”, they are simply “incomplete”. It is a fine point that many laypeople miss entirely.

      2) Aashami’s (and other’s) attacks against Einstein’s personality are not backed up by any objective evidence. They are based on gossip and bigotry. It is abundantly clear that the intent is to discredit Einstein using character assassination.

      End of story.

      • @ commenter
        Ever read the word ” humble ” ….. Try it , it is good for your health .
        We all know that the S.M. Is an effective theory but you as usual could not understand that NO beyond physics after getting the Max. Capacity of the LHC means that (( explaining )) the parameters of the SM is postponed or maybe rendred Unreachable in principle …..that failure of Gravity Probe B if confirmed may point to a new fact , ie , Gravity is not geometry , then if the graviton proved to be non existing then we are on the verge of a paradigm shift .
        See what I mean ???

        • I am always open to entertaining a healthy science debate in good faith. But when you start by insulting people with comments like “ever read the word “humble”…try it it is good for your health”, you close the door to any such debate.

  43. I think we (Humanity) would be being quite nieve to think the standard model describes all process…… Or any theory for that matter!! Mathematics has already gave us the answer in that respect with Kurt Godels- Incompleteness theorem!!
    Personally the as above, so below and the wholeness concept that has been concluded by all the ancient civilizations really should be taken literally. In my opinion holography is the only theory that comes close to this realization, and little by little that and information that underlines will and is, becoming the realization that saves humanity. Separating things in this box and that, and mining the earth thinking it will not affect the whole is where we are going wrong.

    Sorry I know this is my opinion, and I’m not anti-science but we defiantly need a paradigm shift maybe as the above argument suggests, in a different view and words. Peace

  44. Three questions about Einstein, that i hope you can easily reply :

    1) What about a mirror clock , when the light is bumping in the speed direction. For example at v=0.866c (relative to the observer), the length is the half, and the time goes 2 times slower. The static observer see how the light spend lot of time going one way, and a little going the other. v(rigth)= (1-0,866)c , vs v(left)=(-1-0,866)c . How can the moving observer see the ligth at the same speed in each way? (we know for sure that “the two way” speed is c)

    2) At the The Kündig experiment, Source and absorber of frecuencies, spinning. They experimented refshift when the sourse was spinning. Blueshift when the absorber was spinning (not 100% sure about this). And the same frecuency when both was spinning. Where is the equivalence principle? There is another experiment without aceleration that proof how it works ?

    3) Grandfather paradox: If the traveler brother spent 10 years traveling, and the earth brother got 40 years older. How many times the traveling brother saw the earth making a complete turn over the sun? 40 , 10 , 2.5 times? .
    If the answer is 40, as we all should agree(?). The traveling brother KNOW that the time on the earth is going faster , and not slower, as it should be, if they saw their clocks going slower each other.

    You can say I have classical knowledge, because I’m an engineer. But i can’t get the correct answers for these questions.

    Thank you.

    • ad 3) I think you are referring to the “twin paradox”. Yes, if the traveler has studied special relativity, he will exactly know what to expect when he meets his brother again. I think everything which needs to be said about this (non-)paradox can be readily found online, check Wikipedia for example.

      • Sorry you are right, twin paradox.
        I have read all that stuff, but it’s still not solved to me. Because the earth spinning the sun is a “natural big clock”. The traveler brother has to see it turning 40 times, So the clock is going faster. Special relativity says it must be slower.

        If you want we can go step by step on the observations. but if you see any thing going slower, it can’t suddenly have elapsed more time. Its like it have to pass through zero, if a continuous function when pass positive to negative.

        • A remark which may or may not help your understanding: What is measured in the frame of an observer is not directly what the observer “sees”. For measurements in special relativity you basically assume that the whole space is filled with a grid of measurement rods and clocks which move along with the particular observer at the same constant velocity, the clocks being synchronized according to this observer. When the observer changes his/her state of motion (i.e. accelerates) he/she will in general no longer agree with the arrangement of rods and clocks (in particular their synchronization!) set up in the frame of reference before the acceleration. You need to set up a new co-moving reference frame for the new state of motion. This switch of reference frames (which in reality will be a smooth “movement” through a continuous family of reference frames) is exactly what removes the paradox.

          • I am replying your last message here.

            Sorry if my words are imprecise, my english is bad.

            “Also never confuse yourself with questions like “Does time really slow down, or does it only appear so?” Such questions are meaningless and lead only to a dead end of confusion.”

            It’s fun for my, how you don’t make the big questions, and you make a blind jump into a set of equations that make the numbers right. If as you say, it’s easy, I don’t see why this question is meaningless. It should be easy to answer.

            It’s my high interest to understand how the time can bend and what it mean. I know it sound like metaphysics, but i think understanding time is the path that physicist must follow.

            I did the numbers and see how the tics are of the same length, i promise you i’ll go deeper into the equations, and minkowski diagram.

            I only asking that you answer only few questions please. It should be easy ;)

            1) How many Earth turns the traveling brother “measure”?.

            I would like to know what theory tell us. Because when I read this: “the motion of the earth around the sun (or any clock) will be measured to be slowed down in these reference frames on both directions of the paththe motion of the earth around the sun (or any clock) will be measured to be slowed down in these reference frames on both directions of the path”

            It mean to me that the moving observer measure the Earth is spinning slower all the path ( if instant aceleration is supposed), So if the time for the moving observer is 10 years of travel, it has to measure only 2,5 spins. But it doesn’t have any sense. Could you go a little deeper here please?.

            2) Does time really slow down, or does it only appear so?

            3) Why are you sure that “one way speed of light” is constant and c?

            I have searched and did not find any direct measure.

            I apreciate your responses, buy maybe because the lenguage I’m being rude. Thanks

        • No, it does not say that it must be slower. It only says that it will be measured to be slower in the reference frame of a moving observer during the periods of time when this observer is moving at a constant velocity with respect to the sun. Look at the Minkowski diagram on the Wikipedia page and see what happens at the turn-around point of the traveling twin, where the emphasized condition does not hold.

          A nice property of special relativity is that the space-time geometry is actually “absolute” in some sense, so you can really draw everything in a diagram and the worldlines, etc., will be unambiguous. There is no magic going on. You just need to be very careful when you add (which you should do) the coordinate grids used by observers (which are not absolute and can vary with time!) to the diagram.

          • migui250, if you want to understand this, you will need to be more careful and you should also read more carefully what I have written. I explicitly warned you about confusing what is measured in a reference frame with what an observer at a particular coordinate sees. For reasoning about seeing you need to trace light rays in the spacetime diagram and check their intersections with the worldlines of the observers. I suggest that you postpone this to a second step of the exercise after you have understood the first step of setting up the proper reference frames and converting coordinates back and forth between them.

            If we talk about measurements in the co-moving reference frames of the traveling observer, the motion of the earth around the sun (or any clock) will be measured to be slowed down in these reference frames on both directions of the path. The time delation depends on the gamma factor which is independent of the sign of the velocity. The key to understand how this is consistent with the aging of the twins is to understand how any of the twins will at any time answer the question “How old is your brother/sister now at this point in time?” Draw regular question events, the planes of simultaneity, and the answers of the twins in the Minkowski diagram, and you will see a totally clear resolution.

            That said, you can also find lots of explanations for what the twins see on the net. This example has been discussed over and over thousands of times, and there is really nothing difficult about it. You only need to deconfuse yourself and painstakingly define exactly what you mean with every word you say and define it in a measurable sense.

            Also never confuse yourself with questions like “Does time really slow down, or does it only appear so?” Such questions are meaningless and lead only to a dead end of confusion.

          • P.S. delation -> dilation, of course

          • “No, it does not say that it must be slower. It only says that it will be measured to be slower in the reference frame of a moving observer during the periods of time when this observer is moving at a constant velocity with respect to the sun”

            When the moving observer is in the return path (at constant velocity), he will see the Earth spinning faster so the “clock” moving faster. So i am not sure about your statment.

            I would like to know how many times the moving observer will see the Earth making a complete spin.

            And i want to know if the time is really slowing down or it’s a measurement issue, because the time of one observer can’t change depending upon the other observers who makes the measurements.

            Let C be anoter observer, going at the half speed of the traveling brother, he must see the others observers clock slower than him’s.

            The Earth point of view is that the time of C is slower than their own, but (C time ) still faster than the moving brother. When they all return can check this. But why the Earth point of view is more real than the measurements of the travelers? it should be simetric and it doesn’t.

            You say, they could know real time of each observer (bacause they studied relativity).

            If the observers can agree who is moving, we can conclude they could find a observer who is absolutely static. And i think Einstein will not agree this conclusion.

        • Speed of light is constant only relative to Geodesics (the motion of the inertial test particles) ?

    • ad 1: You are right in that the observer who sees the clock moving will record unevenly timed clock events (like “tiiiiiiick, tock, tiiiiiiick, tock, …”). However the observer in the rest frame of the clock will see evenly timed events “tick, tock”. To see why this is consistent, you need to think precisely about the following questions: “Which experiment could the observer A in the rest frame of the clock do to check whether his clock is producing evenly timed events?” and “How would observer B who sees the clock moving by with A describe A’s experiment?” Be assured that there is no contradiction. Hint: The mirrors of the clock are spatially separated. What do you need to be careful about when talking about events at different ends of the clock? It can also be very helpful to draw space/time diagrams (including the 45 degrees light cones) and the coordinate grids for both observers.

      • So you are saying that for the static observer(A), the time of the moving observer(B) not only is slowed down it’s also changing over time, to make the travel time of light the same.

        If that is what you say, i can easy say that is wrong, if we think what happens if we have several pulses with different timing.

        Lets say that the “clock length” at rest 300.000 km , the light need a second to reach each mirror. 2 seconds to return the starting point.

        Lets say its moving now at 0,866 c . Now the length of the clock for A is 150.000 km, and the time should be slowed down by the half. So A expect see the light at the starting point 4 seconds later.

        Lets do some math:

        From the sight of A.

        If B is moving 0,866c, and ligth at c. So the ligth travels from the first mirror to the second one at 0,134c. And it takes 3,73 seconds.

        The return travel will be at 1,866c and takes 0.268 seconds.

        So the whole travel is 4 secounds.

        You told that B, should see the time of the two events at the same rate of time.

        The only way is that for B time goes slower when light is in the first path, and faster when returns.

        But if the clock make a ligth pulse everi 0,05 sec (to A, at rest) , will do it at 0,1 sec when acelerated. We can see 37 pulses going on the first way and only 3 returning.

        Then light is not coordinated to compensate the variable time dilation.

        There are “two way speed” experiments only, and they agree “two way speed” is c.
        We are not sure that “one way speed of light” is the same for all inertial frames, at least as far as i know.

        • Re: “So you are saying that for the static observer(A), the time of the moving observer(B) not only is slowed down it’s also changing over time, to make the travel time of light the same.”

          No, it is not changing over time, it is changing over space! Look at the formulas of the Lorentz transformation, e.g. “Boost in the x-direction” on .

          Space (x) appears in the formula for time (t’), and time (t) in the formula for space (x’)! That is a very important point to understand. The theory teaches us about a particular symmetry between space and time. If you orient your mirror clock with light running parallel to the direction of the boost, the distance of the mirrors will translate into a temporal phenonemon, namely the unequal stretching of the “tiiiiick” and the “tock”.

  45. Dr. Strassler :
    If the analysis of any observation is theory dependent ….
    If our theories does not represent ontology perse…..
    If underdetermination of theories by data is a fact ……
    If unlimited number of theories can be used to explain observations ….
    Then :
    Does that mean we would never grasp reality in itself ? Veiled reality concept is true ?

    • What does it mean to “grasp reality in itself”? How could you ever tell whether you have “grasp[ed] reality in itself” or not?

      I think one of the reasons for the spectacular progress that science has made is the very practical and “down-to-earth” definition of reality that it uses: reality is what you can observe (i.e. measure in physics) in a consistent and controlled manner. (This is my phrasing, no doubt other people have put it better.) If one does not adopt such a practical definition, one can spend the rest of one’s life arguing about words without any gain of knowledge.

      • When QFT assume that “reality ” quantum fields , this is a kind of ” grasping ” reality then we may ask : what if quantum fields are not fundamentals ? Then we are back again with no understanding …. So
        Dr. Steiner : when R. Penrose wrote ( the raod to reality ) he for sure did not mean that reality is a thing we are walking towards it , he must have ment :the raod to grasping / knowing / understanding reality …..
        My concern is : what if fundamentals are not fields ? Would you please answer this .

        • Dear M. Many, it may well be that the fundamental degrees of freedom (or at least more fundamental ones than we know today) turn out not to be exactly described by quantum fields. But this does not mean we would be back at “no understanding”. We would still have an extremely good approximate understanding of nature that is valid over a very wide range of energies. We know today that the Standard Model provides a very good description at least up to the energy scale of the LHC, and quantum field theory in general is probably valid much farther than that.

          You probably feel that you have a good understanding of everyday objects like tables and chairs, etc. Yet you have to realize that your knowledge about these objects is only an approximation, a much coarser approximation than the proven knowledge we have about particles in terms of the Standard Model. When you deal with physics you need to accept that approximate understanding is very valuable and far from no understanding, and it is actually all that we can hope for, because we will never be able to determine anything with infinite precision.

  46. Why are we using quantization if the universe is analog?

    Are we trapped in an endless loop of hypothesis by doing so?

    If we had seen the asteroid that just missed us on Sunday months and years in advance, how many billions of dollars would we have sucked out of governments to create a defensive system against a direct hit?

    • Dear OakTree, the universe is quantum mechanical, that is a proven fact. “Quantization” is just a somewhat phony method for guessing the correct quantum theory from a classical theory, where we know the classical theory to be fundamentally incorrect but still reasonably accurate in a certain limit (e.g. high temperature, large distance, high quantum numbers, etc.). So the (lack of) elegance and logical inevitability of the procedure of quantization is no criterion for judging the validity of the quantum theory. The quantum theory needs to be compared to experiment, and it needs to be checked that it reproduces the classical theory in the limit in which we know the latter to hold approximately.

  47. A question of principle :
    In all particle experiments , it is based on field assumption , are the interpretations theory -laden ?
    Are assuming fields will result in observing fields while in reality there may be something totally different than fields ?
    Note :
    I am not in the physics profession .

    • Analyses as they are done nowadays to interpret LHC results are certainly based on a lot of theoretical assumptions. But you need to realize that these assumptions (also called “physical knowledge”) were carefully build up over a long time, with experimental validation at each step.

      “Yesterday’s sensation is today’s calibration.” – R. P. Feynman
      “…and tomorrow’s background.” – V. L. Telegdi

      That’s the way knowledge is built.

    • A quote from this paper: “If a quantum is a field that is extended over both slits, there’s no problem.”

      I think a physicist who understands the notion of a field in modern physics would never write such a sentence. To say that “a quantum is a field” makes about as much sense as to say that a tone from a violin is the string of the violin. Please don’t take the analogy too seriously, I just want to convey that particles (“tones”) are properties of the theory (“the violin”) as a whole and it makes no sense to say that the property is the constituent (the field or “the violin string”). In many cases certain particles are predominantly associated with a certain field (e.g. the photon is a quantum of the electromagnetic field), a bit like “this tone of the violin is produced mostly by this string of the violin”, but still it makes no sense to say that “the quantum is a field”.

      Again, please don’t take the analogy literally because the relation of quanta to quantum fields is more abstract and not as direct as, for example, the relation of vibrational modes of a classical field to the field.

    BUY: $30.00
    Robert J. Sciamanda1
    Am. J. Phys. 81, 645 (2013);
    NOW WHAT 2

    • “There is no abstract available for this article.”

      Haha, priceless! :)

      Now there’s an opportunity to save 30 bucks, I would say. I really wonder if this guy would walk into a physics lab and tell the same with a straight face to the people who are doing experiments with both particles and fields every day. Particles and fields are descriptions for phenomena that are observed all the time and which are as real as it gets. Sure, the way to think about particles has become more abstract (but also more satisfying!) over time, but that does not remove the phenomena which have been known for many decades (and in some cases for thousands of years).

      • Those two are professors and look at what magazine they wrote in …
        Really i am confused , why should i believe X not Y or Z ?

        • That’s a good question. Ideally you learn enough about physics so you can make an informed judgement yourself. In the meantime you will have to use some common sense about whom to trust. (FWIW, for sure don’t blindly believe me – I’m just studying myself. I think I’m beginning to understand enough of some fundamental things to have my opinion about articles such as the two you cited, but I’m no expert or researcher. But also don’t simply trust anything that has been published in any random journal. Journals are not created equal, and even the best ones cannot guarantee to publish only perfect papers.)

          For example, the host of this site is an expert on quantum field theory, who has workshops with LHC physicists, for example. He calls this blog “Of particular Significance” and writes above “The “Standard Model” is the theory — i.e., the set of mathematical equations — used to describe and predict the behavior of all the known elementary particles and forces of nature, excepting gravity.” (my emphasis) You may take these as a hint to what he thinks about the existence of particles. ;) Also the LHC is a particle accelerator.

          There are good resources for learning about physics on the net. Google for example the lectures of Prof. Susskind. They are excellent introductions between the popular and the fully technical level. Prof. Susskind is a very respected theoretical physicist and he also talks quite a lot about particles. ;)

  49. Prof. Strassler – if you have an interest, your take on the slight kerfluffle at Judith Curry’s Climate Etc blog regarding the proposed use of Bose-Einstein statistics for cloud nucleation rates at low temperatures would be of interest.

  50. @ Steiner :
    When a professor write a paper in a respected journal of physics that there are no particles but only fields , how would I reject it while i know that the concept of particle has nothing to do with particleness ? They observe something , they use QFT , they call that thing a particle , logic does not exclude other interpretations …….this point need Dr. Strassler,s view .

    • I wonder what you find hard to judge in this situation. Once you forget undefinable concepts like the “ultimate reality”, the question really comes down to this: Is the concept of particles a useful one for organizing our observations of and knowledge about nature? The answer is most definitely: yes! And this will not change due to new discoveries, at least as long as we are talking about the range of energies at which we know the SM and its particles to describe nature well.

      Look at this quote by Feynman (from Volume I of his famous lectures):
      “If, in some cataclysm, all of scientific knowledge were to be destroyed, and only one sentence passed on to the next generation of creatures, what statement would contain the most information in the fewest words? I believe it is the atomic hypothesis (or the atomic fact, or whatever you wish to call it) that all things are made of atoms — little particles that move around in perpetual motion, attracting each other when they are a little distance apart, but repelling upon being squeezed into one another. In that one sentence, you will see, there is an enormous amount of information about the world, if just a little imagination and thinking are applied. “

      Feynman said this after developing QED, with the full knowledge how complicated it is to think about particles correctly.

      In any QFT textbook or lecture you will find statements about particles. The Particle Data Group regularly publishes the empirical data known about particles on over 1600 pages. Do you consider it likely that this is all about things which are not meaningful, just because someone writes so in a single article in a journal for physics teachers? You just need to do a reality check with a bit of common sense.

  51. My stand is : I accept what Dr. Strassler once said : we do not know if fields are fundamental , then some observations are made which are called particles while it is a phenomena that can allow different interpretations , OK call it particle but according to QFT it is just a ripple , an organized waving while we can never tell if it is local or extended , we mesured some effect then as we assume that ripples in a field can explain it , we explain it by ripples and field….
    Then comes a question of principle : we do not know if fields are THE fundamentals , then can we discard any other ontology ?
    No we cannot .

  52. Ah…Good Morning ‘Of Particular Significance’. Nice to see you up after your summer sleep. Matt it will again be nice to see your outstanding work on display.

    As to some of my fellow posters: What’s all this Einstein bashing going on? Look it’s one thing to question Einstein’s theories. That certainly does not make you an anti-Semite. But when you call him a fraud, a cheat and a thief of other peoples work …then at least to me, that does move the needle in the anti-Semite direction. He was none of those things.

    Even if his theories eventually prove wrong, as they no doubt someday will, he will remain among the greatest physicists who have ever lived. Alas for those of you who secretly hate him for his heritage, the equations in the theory that does replace his will reduce to his in all the areas where his have been tested. Just as NASA uses Newton’s equations to launch probes in the solar system, so they will continue to use Einstein’s in all the areas that they currently hold up. People, at least for the next several hundred years, will always say: “Galileo, Newton, Einstein, and…” whenever they think of motion and gravity.

  53. Ever thought that it is humans (consciousness) that creates/manifests particles?
    Everything is just fundamentally information. Don’t know how that progress’s science but maybe that realization may take us in a better direction.

    But at the end of the day even Einstein said “Reality is just an illusion, albeit a persistent one”

  54. I loved as much as you’ll receive carried out right here.
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    NOW WHAT 5
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    • So what 3,4,5? My impression is that you don’t love physics, you love the wonderful world of meaningless discussions.

      You should realize that the great physicists of the past and present do not avoid philosophy because they are philosophically challenged or uninterested. They avoid such vague talk and prefer practical and useful definitions because they know exactly how hard it is to say something both correct and meaningful about “reality”, etc., and how unproductive it is to spend time pondering undefinable questions.

      Nature is correctly described by quantum fields up to very high energies which are presently being probed. And the states of quantum field theories can (in many important cases) be organized in terms of particles. Accept it or “go somewhere else” as Feynman has brilliantly put it:

  56. Professor Steiner :
    Once you tell me that the stuff of the universe consists of fields and particles then you give me the right to ask you :
    1- Is that an ultimate fact ?
    2- If not 1 then what you do is confusing every one by mere mathematical factors while the honest way is to say : we observe such and such , we presume that it may be fields / particles , we desist from talking about reality ………., that would be more honest .

    • 0- I’m not a professor :)
      1- What is an “ultimate fact”? How do you know whether a given fact is “ultimate” or not?
      2- In the comments above I have given my working definition of “reality”. I believe that all my statements are correct statements about reality in that sense.

      If you want to know the unknowable and unprovable, science is not the right endeavor for you, I think. I’d like to stop this discussion because I think it is going nowhere, so I will not reply to further “now what?”s.

  57. Professor Henry :
    I believe that your concept would be the correct one , but then allow me a basic question :
    Physicists measure some observation , their physical background is based on QFT , QFT is based on Fields and ” Particles ” , then they interpret the observations as some sort of ” a particle ” and its corresponding field ……
    My question is :
    Does following QFT directs interpretation towards QFT ontology despite the fact that reality may not consist of field / particle Stuff as the primary fundamentals ?
    I appreciate very much getting your kind response
    M. Nader
    Retired professor of structural analysis .

    Sent from my iPad

    As they make their observations, indeed the framework that they have in mind is (currently) QFT. But I don’t think that affects the result of the observation! It may well affect their interpretation of the observation.

    The observation itself is always simply a number.

    The reason that they, as you say, immediately start talking of particles and fields is that such talk has proved so effective in the past, in particular in suggesting perhaps the experiment they have just done: does the result (the number) fit the prediction? So far, success in that has been remarkable. Most recently, the Higgs, now verified to be spin zero, the first spin-zero particle/field. That is a real success!

    That of course does not mean that the theory is “correct.” Indeed, it is widely understood that the theory is provisional and there is high hope that a deeper, cleaner, more comprehensive theory will be discovered. But progress on that has been slow….

    So the answer to your question is, I think, “yes,” but that does not bother me because everyone knows that the theory is only provisional.



    Academy Professor Richard Conn Henry
    Henry A. Rowland Department of Physics and Astronomy
    & Director, Maryland Space Grant Consortium
    & Member, Principal Professional Staff,
    Applied Physics Laboratory
    The Johns Hopkins University
    3701 San Martin Drive
    Baltimore, MD 21218-2686
    vox: 410-516-7350
    fax: 410-516-4109
    This is an honest answer from a high caliber professor .

    • M. Many,
      Please do everyone a favor and take your trolling comments elsewhere. As Edwin Steiner told you, you are only interested in stirring pointless debates that go nowhere.

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