As many people will have read there was a glitch in the surface temperature record reporting for October. For many Russian stations (and some others), September temperatures were apparently copied over into October, giving an erroneous positive anomaly. The error appears to have been made somewhere between the reporting by the National Weather Services and NOAA’s collation of the GHCN database. GISS, which produces one of the more visible analyses of this raw data, processed the input data as normal and ended up with an October anomaly that was too high. That analysis has now been pulled (in under 24 hours) while they await a correction of input data from NOAA (Update: now (partially) completed).
There were 90 stations for which October numbers equalled September numbers in the corrupted GHCN file for 2008 (out of 908). This compares with an average of about 16 stations each year in the last decade (some earlier years have bigger counts, but none as big as this month, and are much less as a percentage of stations). These other cases seem to be mostly legitimate tropical stations where there isn’t much of a seasonal cycle. That makes it a little tricky to automatically scan for this problem, but putting in a check for the total number or percentage is probably sensible going forward.
It’s clearly true that the more eyes there are looking, the faster errors get noticed and fixed. The cottage industry that has sprung up to examine the daily sea ice numbers or the monthly analyses of surface and satellite temperatures, has certainly increased the number of eyes and that is generally for the good. Whether it’s a discovery of an odd shift in the annual cycle in the UAH MSU-LT data, or this flub in the GHCN data, or the USHCN/GHCN merge issue last year, the extra attention has led to improvements in many products. Nothing of any consequence has changed in terms of our understanding of climate change, but a few more i’s have been dotted and t’s crossed.
But unlike in other fields of citizen-science (astronomy or phenology spring to mind), the motivation for the temperature observers is heavily weighted towards wanting to find something wrong. As we discussed last year, there is a strong yearning among some to want to wake up tomorrow and find that the globe hasn’t been warming, that the sea ice hasn’t melted, that the glaciers have not receded and that indeed, CO2 is not a greenhouse gas. Thus when mistakes occur (and with science being a human endeavour, they always will) the exuberance of the response can be breathtaking – and quite telling.
A few examples from the comments at Watt’s blog will suffice to give you a flavour of the conspiratorial thinking: “I believe they had two sets of data: One would be released if Republicans won, and another if Democrats won.”, “could this be a sneaky way to set up the BO presidency with an urgent need to regulate CO2?”, “There are a great many of us who will under no circumstance allow the oppression of government rule to pervade over our freedom—-PERIOD!!!!!!” (exclamation marks reduced enormously), “these people are blinded by their own bias”, “this sort of scientific fraud”, “Climate science on the warmer side has degenerated to competitive lying”, etc… (To be fair, there were people who made sensible comments as well).
The amount of simply made up stuff is also impressive – the GISS press release declaring the October the ‘warmest ever’? Imaginary (GISS only puts out press releases on the temperature analysis at the end of the year). The headlines trumpeting this result? Non-existent. One clearly sees the relief that finally the grand conspiracy has been rumbled, that the mainstream media will get it’s comeuppance, and that surely now, the powers that be will listen to those voices that had been crying in the wilderness.
Alas! none of this will come to pass. In this case, someone’s programming error will be fixed and nothing will change except for the reporting of a single month’s anomaly. No heads will roll, no congressional investigations will be launched, no politicians (with one possible exception) will take note. This will undoubtedly be disappointing to many, but they should comfort themselves with the thought that the chances of this error happening again has now been diminished. Which is good, right?
In contrast to this molehill, there is an excellent story about how the scientific community really deals with serious mismatches between theory, models and data. That piece concerns the ‘ocean cooling’ story that was all the rage a year or two ago. An initial analysis of a new data source (the Argo float network) had revealed a dramatic short term cooling of the oceans over only 3 years. The problem was that this didn’t match the sea level data, nor theoretical expectations. Nonetheless, the paper was published (somewhat undermining claims that the peer-review system is irretrievably biased) to great acclaim in sections of the blogosphere, and to more muted puzzlement elsewhere. With the community’s attention focused on this issue, it wasn’t however long before problems turned up in the Argo floats themselves, but also in some of the other measurement devices – particularly XBTs. It took a couple of years for these things to fully work themselves out, but the most recent analyses show far fewer of the artifacts that had plagued the ocean heat content analyses in the past. A classic example in fact, of science moving forward on the back of apparent mismatches. Unfortunately, the resolution ended up favoring the models over the initial data reports, and so the whole story is horribly disappointing to some.
Which brings me to my last point, the role of models. It is clear that many of the temperature watchers are doing so in order to show that the IPCC-class models are wrong in their projections. However, the direct approach of downloading those models, running them and looking for flaws is clearly either too onerous or too boring. Even downloading the output (from here or here) is eschewed in favour of firing off Freedom of Information Act requests for data already publicly available – very odd. For another example, despite a few comments about the lack of sufficient comments in the GISS ModelE code (a complaint I also often make), I am unaware of anyone actually independently finding any errors in the publicly available Feb 2004 version (and I know there are a few). Instead, the anti-model crowd focuses on the minor issues that crop up every now and again in real-time data processing hoping that, by proxy, they’ll find a problem with the models.
I say good luck to them. They’ll need it.
Jim,
in time the rules, laws, math, citations and so forth will become clearer and will not seem so disjointed. As much as is measured and observed, there is also so much yet to discover, but the tools and most of the technology already exists and all the major discoveries have already been made in physics and chemistry, and they do add up to a cohesive and detailed story, but to post it, takes time.
To be more democratic and balanced here are the more complete contrarian arguments to the IPCC report, actually Jim is basing some considerable weight on his thoughts on Kirchoff’s law based upon these arguments and accusations of the IPCC and supposed violations of Kirchoff’s law, so to include such reports with a flood of empirical data and spectroscopic analysis is imperative to unwinding the argument through direct analysis of what we have measured, what assumptions are based upon inviolable laws and what, may not settled yet in the science. The IPCC report is impressive and I have read it many times and I intend to look at the parts that relate to this line of argument, but first I am establishing rapport and looking at the contrarian arguments like anything else in science, objectively and with great care and patience. Some assumptions are not upheld by solid evidence while others are merely technicalities and are foolish to debate over, but not knowing where Jim would like to take this exactly, well, the arguments must be known and understood, the actual measurements, experiments, numbers crunched, graphs, data etc… I assure you I am not working in one direction, taking any report (including the IPCC report, or Hansen) or blog at face value. Now obviously I cannot perform every experiment or actually work in every industry and have access to all proprietary data or certain coefficients (I play with graphs and various multipliers, parameters, and scenarios) so we must all have faith in science, we must trust some people’s work, but when speaking to a person like Jim who is sharp, but may be missing some key elements, how better to answer an inquisitive mind, by throwing down reports where the attributions are difficult to understand by most people, data that they may be predisposed to believe is biased alone, or to talk it through? Of course I have cited legitimate peer reviewed lit and reputable textbooks, but this is a place to discuss and yes, debate while bringing up those materials that are controversial, down right wrong, so so and extremely accurate, but what is the standard to judge accuracy, when so many different people from various backgrounds and perspectives come here and write out political views, encyclopedia articles, their own field work, where sometimes the ‘alarmist,” is more dangerous than the denialist or skeptic when it comes to an informed discussion.
http://www.john-daly.com/forcing/hug-barrett.htm
Incidentally they do make some correct assertions regarding LTE versus GTE, and if it were left there, one might get a partially informed, scientifically correct explanation and come to the wrong conclusion.
The Oceans and Climate
By Grant R. Bigg Good treatment of this subject on GOOGLE books search. (yes I read
what I cite and post)
There is of course an overlap between several of the textbooks and the journals I cite, but with the confusion I still see here and the elementary questions asked, people are just not reading or if they are, they are not understanding.
Some of my students are denialists, but they create very sophisticated arguments, better than I see in the denial camps and more sophisticated and believable than many ‘alarmists.’
My last recommendation for a long time regarding this subject; Hypersonic Aerothermodynamics By John J. Bertin
Jcbmack, for Christ’s sake. Get a blog.
BPL 581: Photons have no REST MASS.
They do have a relativistic mass.
Come on! That’s REALLY basic A level physics (cf High School, 18 yo).
And going at light speed, relativistic mass goes to 0/0 which is undefined (see also Sin(x)/x when x->0) so can only be calculated to a value if you have how the zero’s are being approached by the numerator and denominator.
And the result is that if the energy of the photon is E, it’s relativistic mass is
m=E/c^2
Which lead to the equation:
E=mc^2
You may have heard of this one…
Guenter, 582.
OK, so where’s the beef?
If a/A is going to zero is the problem, then the last denominator tends to 1 and we have what I put in earlier: the number it goes to overall depends on how B/b goes to zero and your problem with the value as pertains to a/A being zero is moot since you only have a problem by ignoring B/b.
If a/A is going to infinity, then the 1+infinity is effectively infinity and you should cancel out the A and a terms and you have terms relating to b and B. Which was pointed out in 579(?) by me.
Overall, I’m afraid I don’t see where the beef is. The only possibility is that you’re forgetting there are more terms than a/A in the equation and they aren’t constants so have a say in where the overall number is going as you change a and A.
Mark #606,
Let me rephrase my original post and state the equation from J. T. Houghton again.
Js=(Iv+((c*b12*A21)⁄(4*π*a21*B12)*a21/A21))/(1+a21/A21)
Would you agree: if a21/A21 goes to infinity then A21/a21 goes to zero?
So the remaining value of the brackets ((c*b12*A21)⁄(4*π*a21*B12))
goes to zero, if one does not provide an additional argument why the brackets remain at a finite value? I am just missing this argument in J. T. Houghton’s book and was asking if anyone can provide it.
Best regards
Guenter
Mark is right Barton, high school physics.
607. Only if you don’t change b/B. In which case you can get nonzero again.
Or c could change to infinity too, giving infinity divided by infinity which is undefined again.
So for there to be a problem, you have to show that in such a case, b/B or C don’t likewise change to infinity/zero.
Mark #607,
Thanks again for your patience.
You wrote:
“Only if you don’t change b/B. In which case you can get nonzero again.Or c could change to infinity too, giving infinity divided by infinity which is undefined again. So for there to be a problem, you have to show that in such a case, b/B or C don’t likewise change to infinity/zero.”
Wouldn’t you think the author of the equation should have specified that more clearly? Or should the reader speculate?
I called that initially mathematically questionable or ill defined, is it not?.
I was just looking in this forum, if somebody can kindly fill that gap the author left me with. The equation is the central equation to understand LTE and non-LTE situation and I like to get that clarified.
With c Houghton describes the concentration of the absorber.
Capital B12 is the Einstein coefficient for absorption. With b21 he describes the Einstein coefficient for activation by collision.
Best regards
Guenter
Richard, I do not have the time or patience to focus on my own blog with the detail it would need.
Mark,
Photons have momentum. They do not have mass. You can invert the Einstein mass-energy relationship and use it to say “this is the mass of a photon,” but you’ll still be wrong.
And photons can only travel at the speed of light.
Mark is wrong, jcbmack, college physics. Photons do not have mass. Deal with it.
High school and college physics are both approximations, and nobody publishing in physics journals is claiming everything important is known. Find that claim on blogs.
Make the effort and you’ll find information like this:
“… If the rest mass of the photon were non-zero, the theory of quantum electrodynamics would be “in trouble” primarily through loss of gauge invariance, which would make it non-renormalisable; also, charge conservation would no longer be absolutely guaranteed, as it is if photons have zero rest mass. But regardless of what any theory might predict, it is still necessary to check this prediction by doing an experiment.
It is almost certainly impossible to do any experiment that would establish the photon rest mass to be exactly zero. The best we can hope to do is place limits on it. A non-zero rest mass would introduce a small damping factor in the inverse square Coulomb law of electrostatic forces. That means the electrostatic force would be weaker over very large distances.
Likewise, the behavior of static magnetic fields would be modified. An upper limit to the photon mass can be inferred through satellite measurements of planetary magnetic fields. The Charge Composition Explorer spacecraft was used to derive an upper limit … slightly improved in 1998 by Roderic Lakes in a laboratory experiment …. Studies of galactic magnetic fields suggest a much better limit …, but there is some doubt about the validity of this method….”
http://math.ucr.edu/home/baez/physics/ParticleAndNuclear/photon_mass.html
Guenter, my recommendation would be to keep focused on the physics. Nothing is really going to either infinity or zero. Rather a21 is simply much, much greater than A21, which enables you to equate [a21/A21]/[1+(a21/A21]=1. At the same time, I think A21/a21 will get very small, but is still finite, not zero. Houghton is just being a little fast and loose with terminology.
BPL, 612, so you must know what, essentially, mass IS, then, to know that there’s a mass that
a) imparts momentum
b) is affected by gravity
but isn’t mass.
No, really, please tell.
Why is relativistic mass of a photon not relativistic mass of ANY OTHER PARTICLE?
And while you’re at it, think about massive neutrinos that travel at the speed of light (part of the standard model).
It’s High School that tells you that photons are massless.
It’s a lie to children.
Called teaching.
Barton, you are mistaken. That is like saying electrins do not have mass… some courses in colege emphasize that they do not, but actually they have a very negligible mass.
E=hf where h is planks constant and f is frequency of light. Photons move at the speed of light and have and carry a certain amount of energy is equivalent to a certain amount of energy. E=MC^2 and the amount of mass is E/c^2. p= EV/C^2 since the photoelectric effect tells us nothing about about the momentum of a photon. here is the issue, a photon is never at rest and we can use equations that assume zero resting mass of a photon.
Photons have an angular momentum independent of the frequency (v) and behave as a wave with no mass. Yet a photon is also thought of and behaves as a particle with an angular momentum with eigen values of +/- h/2pi. (boson) Even if one prefers the wave understanding, a photon still contains energy is affected by gravity and in this way has attributes of a particle which contains mass.
Do not forget about the relationship between frequency and wavelength: V=C/Lambda, but what is interesting as well is that the energy of a photon is momentum times c. C must equal one as nothing travels faster than the speed of light and you cannot have more than 100% energy.Photons can be destroyed, but cannot be slowed or stopped, though due to the effects of quantum mechanical tunneling, light does come through slighlty slower than C outside of a vacuum. As long as 100% of the (theoretically) mass is utilized as energy then we can confidently say a photon has no mass.
Check out the Proca equation, the Evans- Vigier field equations and some other field equations dealing with photons as having mass.
In your journey you will encounter Dirac’s theory, matrices (cramer’s law) and a bunch of head twisting facts about both electrons and photons.
I am low on time, I will post up a few references to get you started.
617: neutrinos, I think you meant.
Of course, there are *electron* neutrinos (and tau and a couple of others I can’t remember off the top of my head).
But anyway, what is momentum:
Mass times Velocity.
What’s the photon doing with momentum then, if it doesn’t have mass?
“But anyway, what is momentum:
Mass times Velocity.
What’s the photon doing with momentum then, if it doesn’t have mass?”
This is analogous to asking what the wave is doing, if there is no medium.
Things are rather different in magnetic fields, of which electromagnetic radiation (photons) is an example. DeBroglies hypothesis gives wavelength = Planck’s constant / momentum. One can solve this equation for momentum = Planck’s constant / wavelength for light, without assuming a mass.
Mark, it’s a FAQ. Just not a climate FAQ.
See “the web version of the Usenet Physics FAQ” –>
http://math.ucr.edu/home/baez/physics/ParticleAndNuclear/photon_mass.html
Hamilton you are correct on the DeBroglies hyothesis. Mark I meant photons though there applications to neutrinos as well. What I am basically saying is there is just a mass energy equivalence. Depending upon the math used and the understanding of the photon wave/particle duality, the interpretation will vary with the experiment or the approximation made. We do not need to assume mass to get correct results, but some phsyicists do assume mass and also get correct results. Mass is converted completely to energy therefore there is in a real sense no mass and recall the speed of light is a constant. I was being a little sarcastic, to me this whole argument is something out of high school. Even high school regents books do a superficial, but reasonable job in explaining the photon.
Now, to a particle physicist (not all, but many I speak to and reference) they may prefer to consider resting mass of a photon to exist, as well as some theoretical phsyicists. Read:
http://www.journaloftheoretics.com/Editorials/Vol-6/e6-3.htm they also make references to descriptions made in Nature.
Except from http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/961102.html:
Ask an Astrophysicist:
The Question
(Submitted November 02, 1996)
This questions has been bugging me and my chemistry class. Does light have mass? Most people would think not but here’s why I argue against it. Even though light does not effect anything it its path like a solid object, it is affected by gravity. Anything that has mass is affected by gravity. Why do I say that light has mass? Well, If a black holes gravity field is so strong that light cannot escape itself, light must have mass? Am I right? Everyone argues against it.
Enter Albert Einstein. In 1915 he proposed the theory of general relativity. General relativity explained, in a consistent way, how gravity affects light. We now knew that while photons have no mass, they do possess momentum (so your statement about light not affecting matter is incorrect). We also knew that photons are affected by gravitational fields not because photons have mass, but because gravitational fields (in particular, strong gravitational fields) change the shape of space-time. The photons are responding to the curvature in space-time, not directly to the gravitational field. Space-time is the four-dimensional “space” we live in — there are 3 spatial dimensions (think of X,Y, and Z) and one time dimension.
Now, being scientists, we do not just accept theories like general relativity or conclusions like photons have no mass. We constantly test them, trying to definitively prove or disprove. So far, general relativity has withstood every test. And try as we might, we can measure no mass for the photon. We can just put upper limits on what mass it can have. These upper limits are determined by the sensitivity of the experiment we are using to try to “weigh the photon”. The last number I saw was that a photon, if it has any mass at all, must be less than 4 x 10-48 grams. For comparison, the electron has a mass of 9 x 10-28 grams.
http://math.ucr.edu/home/baez/physics/ParticleAndNuclear/photon_mass.html
As was the case with Jim there comes a point where words really do not suffice, it just becomes long equations, lots of different types of math and approximations.
Mark I see what you meant, I was referring to electrons and neutrinos, but did not have time to type out the thought, when one argues about a photon, a good textbook does a good treatment of electrons first.
http://www.weburbia.com/physics/photon_mass.html describes relativistic mass, but it is not necessarily mass itself, it is the energy change that is equivalent to mass, Barton and Mark have one side of the same coin argument going on here.I swear I took to many courses in the colleges I attended, I would never do it again, it was tiring.
One further note: when the term mass is used, people usually mean rest mass. The photon is never at rest.
Certanly light moves due to some force so thinking of photons has having mass like qualities cannot hurt.
jcbmack, OK, this is off topic, but: actually, from the point of view of the photon as the gauge boson for electromagnetism, masslessness is critical to the theory. When symmetry was broken between the weak nuclear force and electromagnetism, the W and Z bosons gained mass, while the photon did not, and this explains the drastically different natures of the two forces. So, while it may be convenient in some cases to think of the mass equivalent of photon energy, it’s never truly correct.
ReCAPTCHA waxes poetic about symmetry breaking: hiding music
Ray,
in that case you are right and in general that is a correct statement, but that is not an unanimous assertion in the physics community or in all subdivisions. Also if you read my prior posts, I generally come to that conclusion, but in certain cases in infinitesimal moments photons can be thought as having a mass. The photon is not at rest so we cannot speak in literal terms of a resting mass. More on this and related topics soon, and as always I enjoy your posts as you are the only blogger here I believe is in physics for real. Us chemists can tell.
Ray, also keep in mind I was being a little sarcastic with Barton and Mark’s debate.
#619 However, Alexandre Proca under de Broglie’s guidance wrote a modification of Maxwell’s equations which provides for non zero mass (though very small) of a photon while preserving the invariance of electrodynamics under the transformations of special relativity. The Lagrangian density Proca wrote is: L = −F αβ F^ αβ /4 − m 2 c 4 A α A α /2(hc) 2 ,(3)
with F αβ = ∂α A β − ∂ β Aa.
Now, personally it does not matter at all if a photon has mass or not, in regards to out discussion here, and when I teach a general chemistry or physics students, I tend to say they have no mass and call it a day, or if they persist, I show them and tell them how complicated it really is, and they stop asking questions.
Basically for all intensive purposes, either Mark or Barton may be considered correct, however, the arguments get real nasty if we are to really proceed with it, but I suspect that is NOT the general consensus whether or not the people have a background in this subject matter or not, because who do know most textbooks even college will tend to dismiss the issue in a simple manner, but the ongoing research takes us to all kinds of hypotheses and theories. It is difficult to talk of this in words at all, without all the expansions, corrections (math does not work without several transformations, I am no mathematician and do not want to be, but the adaptations required in the physics and chemistry is enormous, x and y coordinates do not even get to the answer in orbitals as an off topic, but relevant example, they must be converted, as well as when we deal in polar or non polar coordinates or with eigen functions or values with photons)
I have seen Mark make several good contributions to these threads, what I wonder is will there be solid points on either side of this discussion, there are many variations and takes in the fields on this topic, but it does not build green communities or a bridge for that matter, we need more engineers in these threads and more engineers assisting in correcting GHG emissions.
Then again I have seen some mathematicians hair go white when they say the Physical Chemistry mathematics summed up in but an instant.
Ray, you and BPL seem to be forgetting I am not saying the photon as a non-zero rest mass.
But when it is there and traveling at C, it does have mass.
The problem with “think of the mass equivalent of energy” is that we don’t know what MASS is.
My professor had this meme firmly set in his head but it was my first week at university and I should have said “So what is MASS, then?” but I was too green and thought that a professor would know.
But he didn’t. Nobody does.
Hank, 620. See about “lies to children”. It’s a FAQ. Not a deep delve into the deeper reality. If you stop a photon, it disappears. However, if you stop a positrino with your hand, it disappears.
What is mass. The FAQ doen’t say except the nearly tautological “photon’s don’t have it”. They don’t at rest.
And how about the other way? If you push a mass it moves. Force = mass x acceleration. Mass. But if you get fast enough, you need more force to make it go faster. Force hasn’t gone down, but acceleration has. So mass has gone up.
But that’s EXACTLY THE SAME PROCESS as gave a photon its mass.
Worse, if you go close enough to a particle, it is figured that you will find the masses different in the same way that the electron charge is shielded somewhat.
How about the elecron itself. gravity is caused by mass and depends on the density of the mass. But an elecron has no physical extend (to the best of measurement, provably). so if it has ANY mass, it has to be infinite density.
Opps.
Again, mass as being something special is unsupported.
The only difference between the bosonic photon and the baryonic matter is that the photon has zero rest mass. Stopping it kills it. But, it can re-create itself and continue its journey. That’s how you get refraction and a lower than speed-of-light photon in a medium: it stops for a rest at an atom, adding to the time it takes to move from A to B, traveling at the speed of light between these stops but overall taking more time to cross the distance.
But these oddities are not addressed in the FAQ, are they.
Because they are pretty deep but don’t illuminate anything that has much of a difference.
t_p_hamilton: the photon creates it’s own medium (magnetic field change causes an orthogonal electric field change, the changing electric field causes an orthogonal magnetic field which retards the earlier magnetic field and creates an orthoginal electric field which retards…).
A longitudinal wave its own medium.
I’m afraid your analogy is incorrect.
Please, explain the question. Why is it mass when matter is imparting momentum but not when a photon is. What IS mass. You missed that in trying to craft a pointless analogy that doesn’t work.
And those equations are not reality. They are the mathematical analogue of the effects of reality. Much like “gravity is the newtonian force between massive bodies” gives you the ability to slingshot probes billions of miles to orbit and pass bodies within 10 miles yet it isn’t what gravity IS.
Reality is what it is. Our theories are the best explanation of what we see it doing. They aren’t the reality. Which is why they can change (as opposed to more fundamental christian who believes the bible IS reality and therefore cannot accept any option that there’s something wrong with any event that doesn’t fit with it). A christian who believes that the Bible is an explanation written down of reality knows that people explain things poorly sometimes and miss stuff out. And can therefore accept a real world that shows evidence of actions that do not conform to the explanation.
Don’t treat maths as TRUTH as per fundie.
Yet further off topic: I did find this result
http://news.yahoo.com/s/afp/20081120/sc_afp/sciencephysicseinstein_081120235605
The story concerns the rest mass of the proton, which is substantially greater than that of the quarks and gluons that make it up. Theorists have long contended that the difference is in the kinetic energies of the constituents–and it turns out that works well as an explanation. Not pertinent to photons per se, but it does show energy/mass equivalence.
The FAQ gives the cites to the experimental work. Beyond that it’s “arguable” if you enjoy the digression. Smaller than a molehill.
Mark, mass is a result of symmetry breaking of the electroweak force. It’s connection to gravity and inertia, the equivalence between gravitational and inertial mass and so on–those are the really deep mysteries. (BTW gravitation does not depend at all on density–only mass and position.) In particle physics, when we speak of the mass of a particle, we are referring to its rest mass, as that is the relevant quantity for understanding its behavior, and the only unambiguous definition of a particle’s mass. Also massless vs. massive gauge bosons give rise to dramatically different characters for the force they mediate. It is my fervent hope that we will understand mass much better once the LHC fires up in earnest.
Mark said:”t_p_hamilton: the photon creates it’s own medium (magnetic field change causes an orthogonal electric field change, the changing electric field causes an orthogonal magnetic field which retards the earlier magnetic field and creates an orthoginal electric field which retards…).”
Quantum field theory says there is a zero point field with ZERO photons. The medium is space itself. If you place an atom in an excited state in a cavity is constructed such that there is no zero point field corresponding to the frequency of spontaneous emission, then a photon will not emit.
“Please, explain the question. Why is it mass when matter is imparting momentum but not when a photon is. What IS mass. You missed that in trying to craft a pointless analogy that doesn’t work.”
Indeed, what IS mass. If you wish to use relativistic mass, which in the case of the photon is all that it has, it is fine to do so for photons as you have been arguing.
Here is the problem with such an approach:
Particles that have a rest mass cannot go at the speed of light because the kinematic mass becomes infinite, via a relation of how the rest mass gets multiplied by a factor that becomes infinite. Massless particles (i.e. zero rest mass) such as photons do not have this limitation. That is why the distinction is made.
This is why speaking of the momentum of a photon as just mv= mc has problems – it invites people to think of photons as if they were a “regular” particle with a rest mass, since that is what the m in p = mv is.
Neutrinos have rest mass, hence they do not travel at the speed of light.
Ray, 634. But the gravitational strength does depend on density:
F=GMm/r^2
But the Mass of the object depends on the density:
M~4Dr^3
So if the entire mass of the larger body is within your radius,
F=4GDrm
Density.
So if you get closer to an electron, the gravitational force is higher.
See?
Now you could have seen that yourself except you were concentrating on how I was wrong.
Did I tell JCB that he was wrong and that electrons DID have mass? About 511KeV IIRC. No. I figured he could be right if he misspoke and meant electron nutrinos.
You know, it’s funny that just recently I was lightly lambasted for being agressive in my querying. Yet when it comes down to it, the ones that complained about me are just as bad.
Funny odd, not funny ha ha.
But then again, one thing that annoyed me about “Volcanoes do more in one year than humanity has done in its lifetime” was I couldn’t understand how such absolute nonsense could be spouted. Someone looked at the figures and thought it right. Or at least not trivially provably wrong.
Then I figured it out: someone was talking about the great extinction when supervolcanoes DID gush out trillions of tons of CO2 and other nasties over a short period of time.
And now I could see where it came from.
And so I could counter it: When did the volcanoes do all this?
They either answer wrong (Mt St Helens) and you can counter that with real figures. Or they own up they don’t know and you mention the great extinction and ask them if they think we would survive that? And no, we wouldn’t, so it’s hardly safe to say we’re a little better than that event.
But back to Ray’s points.
They don’t answer what mass is and why the relativistic mass gained by a boson is different from the relativistic mass gained by a photon is different.
He says that they undergo different forces, but then again, so do quarks. And WIMPs. Yet they have mass. Gluons? Nutrinos? Maybe. Neutrons don’t undergo electric forces. Does that make them not matter?
So saying that photons don’t have mass when moving because they aren’t bosons is, as I put earlier with a similar reply, tautological.
I do think that the LHC wiull show us something, even if it’s just “that’s not the answer”. However, if it finds the Higgs boson, that only tells us where inertial mass comes from. It doesn’t help find out why gravitational mass is there.
And as far as I know (which has been proven lacking before), there’s still no idea whether Higgs particles interact with photons or whether they are only sharing the interaction. Heck, we don’t even know the nutrinos have no mass.
So unless you know better, photons have mass. There’s no difference between them and, just like axial spin around a diatom has no energy in that axis (because you can’t see it spin since it is symmetric around the axis), if you can’t tell the difference, there is none.
Heck, general and special relativity RELY and ABUSE that notion to get their way:
Special: Light speed is constant for any observer
General: You can’t tell the difference between gravitational acceleration and lateral acceleration
Pretty darn fundamental. If you can’t tell the difference, there is none.
And to get waaay back into topic, that non-zero mass of a massless at rest photon comes about because although relativistic mass is gamma times rest mass, when gamma becomes infinity, you don’t necessarily have zero any more.
(the oracle says: of homer. It does seem a little like that…) ;-)
635: t_p, that’s a consequence of uncertainty, not quantum. Quantum is why you can get energy out of it: place two planes side by side close enough and you can’t fit all the energetic waves in there and the lack of some of them means there’s a mismatch between the energy between the plates and the energy density outside the plates.
That has NOTHING TO DO with photons and how they work, though.
Nutrinos have to have mass for the standard model. But they have to go at the speed of light.
Ooops.
And, since you never get a photon not moving at the speed of light, making the point is pointless.
Again.
There is no distinction beteen the MASS of a photon and a mass of a particle. Except by the speed they are going.
Note: in many, many cases, real life ™ doesn’t do infinities. The infinities are part of the mathematics used to describe the model of what real life ™ does.
Did you READ what I put in #631? It doesn’t seem like it.
So the maths says c is impossible because 1/(c^2-v^2) becomes infinity.
Now what really goggles me is that this whole stuff started because of Guenther’s comments about infinities and zero’s. Which was eventually closed one would hope with Ray’s comment #615.
Which is exactly as applicable here.
You can think. Do so.
Coda on 635: neutrinos *according to the standard model* have mass. But if they have mass then the proton decays into a neutron which has not yet been seen.
They don’t necessarily have rest mass. The standard model assumes they must.
Then again, they don’t seem to be traveling sublight either. What, then, if you know they don’t travel at the speed of light, is the speed of a nutrino?
Please stop making the model==reality mistake.
Mark, Gavin has been more than tolerant of this little digression. Just a couple of things. First, photons are bosons–massless ones, which therefore means that the force they mediate has a 1/r^2 dependence. And in fact, it does, to arbitrary accuracy. Second, the standard model does not “assume” neutrinos have rest mass. Rather, the observation of neutrino oscillations shows that at least one flavor of neutrino must have mass. (Note, my first particle physics experiment was a neutrino oscillation experiment.) Third, no gravity does not depend on density, but rather on mass and distance. It doesn’t matter whether the matter exerting the gravitational field is soap bubbles or degenerate nuclear material. Finally, the kinematics of particles traveling null paths (speed of light), is different from that of massive particles–gamma don’t enter into it. A null particle must always travel at light speed. A timelike particle must always travel slower, and a spacelike particle must have imaginary rest mass.
If you would like a good reference to improve your understanding of particles and fields or of the standard model of particle physics, I would be happy to look through my library and see what I can recommend.
“Please stop” is a good idea. Wait for the experimentalists to narrow the range of uncertainty.
That’s the nice thing about being able to experiment.
If we had a spare planet we could wait for the climatologists to do the same. But alas, it’s different for climate science.
Mark,
actually natural events like volcanoe eruptions and create eruptions and explosions (meteorites) in the teraton region and even higher. If we were to have a large volcanic eruption which is quite possible, then we couldbe sent back into an ice age and if it occurred by a society, many people could be killed, injured and displaced. Nothing we can do in the artificial realm can match the awesome forces of nature, to be sure, we have amazing adaptive capacity, however, when nature wants to have her way, she has her way.
Mark, I also tend to agree with you to some extent, but there are absolute and even natural, inherent mathematical truths, without getting into a descartes, Hume and Kantian argument, it should seem somewhat apparent that some math is exact, not approximate or subject to precision and precision error. Now, in quantum states, statiistical mechanics and so forth, we must rely upon a combination of laws, theories, hyptoheses, experiments and those in between statements known as postulates. Now with the postulates of quantum mechanics we must make assumptions and along the way, corrections, but without them we would have no way to access physical chemistry or many aspects of quantum physics whatsoever, yet they have stood up to the test of time. Also, themrodynamics is truth, not a vague or theoretical theory or amendable law. No matter what specialty in physics, math or chemistry we all know that there is no possible way to violate thermodynamics, Stephen Hawking tried and failed and had to scrap his old theory of black holes where he believed that matter and energy disappeared in them, which would violate the first law. (we are not even sure the event horizon exists as of yet)Now regarding electrons and misspeaking (no I am not just trying to prove you wrong, we are talking this out as we should as scientists) it relates back to you earlier statement about lies to children and undergraduate students. We often tell early students to consider electrons themselves to have no mass or that it is so negligible that it is unimportant at this time. Only Pchem and the implications of quantum mechanics can really explain what an electron is, how the probability of its position and momentum are calculated and understood, other than that we “lie,” to out gen chem and even organic chem students in many way. Sigma positive and sigma negative charges for example do not actually mean there are positive or negative charges, no these charges do not exist in nature, it merely means that two like charges (or forces) repel and two different attract.
Now, the models, no argument there, models can be quite effective, but do not belong in absolute truths, like in a Platonic forms sense, nor do they tell absolute truth, but the laws of physics do and without chemistry physics would be quite void and theoretical (the chemists take truths from their approximations and make lasers work in CD players and photodynamic chemotherapies etc… these are absolute facts by their very nature.)The GCM’s are another example, no one knows all the states of the atmosphere oceans and surface, that is too vast, but the GCM’S do a good job at approximations and inl light of much emprical data, or truths provide insights and a good idea of how the burning of fossil fuels are contributing to warming and of course at times dimming and cooling.
Back to photons, both arguments have validity as I stated before, as depending upon ones own mental schema or representation of the facts, laws, theories and approximations, specialized field(s) and the professors they actually had, (my early gen chem professor was a physical chemist and influenced me and constantly taught physics and cosmological principles while teaching gen chem, and (his thermal expansion was the worst I have yet to hear, after class in his office) the lasting ways of looking at the concepts. No two scientists see exactly the same way a law or theory precisely, just no two people in the world perceive color exactly the same (even twins) either.
Regarding neutrinos, as already stated I see what you meant there, and I have no argument about neutrinos, only that I misspoke, since you already agree we must lie to undergraduates. A real conversation here, if one develops would involve very few words after all and lots of mathematical expansions, which I have no trouble doing. After pchem graduate level physics courses of which I took a few, were not a problem, neither was nuclear chemistry nuclear physics or the understanding a graduate textbook in astrophysics, though that is the field you work in, it is just one slice of a much larger pie.
Having said all of that, I like your argument in favor of photon mass relativistically, since this is a general consensus among many physicists and chemists anyways. I like Ray’s argument as well from his perspective in radiation physics, and it also concurs with many in related fields. One of my physics professors years ago argued elegantly that we could never really know if a photon has masss or not, another argued vehemently with all kinds of equations and postulates that is certainly does NOT have mass, still another led me to a book, which I long ago lost (when I recall the title I will recommend it) which argued that in an infinitesimal point in space time, a photon literally has a mass literally, and other than that it does not.
Now in a sense as an object approaches the speed of light it reaches infinite mass, and at the speed of light all mass is convrted into energy and has no mass, but mass equivalence. Elementary I know, but sometimes people cannot see the forest for the trees.
1/838 of an AMU is not easy for an early chem student to understand. Mass at that point requires a different perceptual understanding, yet literally it does have a slight physical mass, whereas photons are far more difficult to narrow down with any measurement tool we have at our disposal so at that point it becomes even difficult for those who are experts to agree on such an issue and concept.
Yes agreed, Ray, Gavin has been very tolerant, if you guys want to consider having this conversation elsewhere on a more technical level, let me know. One word of caution, both Ray and Mark have made valid points, if one comes from the perspective of Penrose, Ray is right regarding photons and mathematical truths, and if one follows some of the more theoretical physicists than Mark is right. I agree with Hank and Ray on this one, this is not the place to post 2 pages of data three of math and long winded arguments outside the sope of global warming, but I am game for a real discussion elsewhere, still senior AP high school meets sophomore college.
“So the maths says c is impossible because 1/(c^2-v^2) becomes infinity.”
Sometimes the infinity is useful, for example, it explains why particle accelerators have this speed limit c. In other cases, there is a clear breakdown because we have gone into a realm in which no experiments have been done, and the theory which says infinity may not apply. Your gravity example for point particles but using theories derived from nonquantum systems being one example.
“Then again, they don’t seem to be traveling sublight either. What, then, if you know they don’t travel at the speed of light, is the speed of a nutrino?”
Pretty close to the speed of light? :)
“Please stop making the model==reality mistake.”
Models are useful, and improved models are more useful. I believe that the latter is closer to reality than the former. If you do not believe that, then it seems pointless to learn science (voluntarily) at all.
Sometimes simplified models have useful insights to give, even though they are not reality for sure.
I am pretty flexible, but if I had to bet on whether a particle with rest mass can’t go at c, or whether the neutrino particle has mass or not (or travels at c or not), I would pick the latter as being more uncertain. Maybe there is another explanation of neutrino flavor oscillation that does not require mass.
T P Hamilton, a pretty good reference on neutrino oscillations, including solar neutrinos. There is no way to get neutrino oscillations without at least one flavory having nonzero mass. Bruno Pontecorvo is the guy who worked out the theory back in the 50s–long before it was observed.
http://cupp.oulu.fi/neutrino/nd-osc.html
You will remember that the deficit of neutrinos initially caused many to question how stable solar output was–thus returning the subject to a more climate related subject…
Ray, if you want to stop, you should have just said “stop”.
Continuing on yourself is quite rude: either they answer and look like meanies or they let you have the last word even if there are elements they wish to either discuss, disagree or counter.
So I’ll do better than that: tell you off for telling someone else to do something you don’t do yourself: stop the offtopic thread.
I did pull it back in with why the thread went OT: 0/0 and Guenter.
Dear All,
Is the follwoing generally true? I believe it is, and if so may help in understanding.
An inevitable property of massless particles is their lack of rest. Hence rest mass is neither an option nor meaningful. Sorry if that is a bit cute.
Mass is in that sence the ability to be at rest. (A Quantum Mechanic might argue whether anything can ever be at rest, I am sure.)
Best Wishes
Alexander Harvey
Mark, Mea culpa, however, I’m afraid it doesn’t take much to get me going on particle physics. I did my PhD in the subject, and since I don’t work in it, I don’t have much call to deal with the concepts. I am serious, though, if you want to learn more about the standard model, I’d be happy to recommend books. It really is a beautiful theory.
Mark 636. The interpretation of “r” is not the same in the two formulae you give for gravity and mass-density. The substitution of r^3 over r^2 doesn’t yield r, since the r’s are not referencing the same quantity.