View Full Version : OT: Oh oh... Possible error in QED with very strong experimental evidence.

While not a subject of much attention for most the Theory of Quantum ElectroDynamics (QED) is one of the best established and solid (they thought) theories in physics. It deals with how electromagnetism and light interact with matter. It has everything to do with atomic level electronic interactions and optical systems, reflection, lasers, lenses and all related phenomena. Without QED, Quantum Mechanics cannot deal with light. QED is an essential part of Quantum Field Theory. Everything we think we know about how light works is based on QED.

It has just been reported that an experiment performed at NIST has produced a result that does not agree with QED. The discrepancy is very large and the certainty is 5 sigma. The experiment is relatively simple and easy to replicate. The observation is simple to make: Under certain fairly uncommon circumstances highly ionized titanium emits a different colour of light than QED predicts. This goes directly to the heart of QED. It remains to be cross checked and replicated but it doesn't appear to be an experimental mistake. The paper has been published by Physical Review Letters, one of the most respected journals in science.

http://prl.aps.org/abstract/PRL/v109/i15/e153001

Popular story:

http://www.nanowerk.com/news2/newsid=27724.php

Tony Ennis

11-28-2012, 09:49 PM

Perhaps it is incomplete, and not incorrect.

A.K. Boomer

11-28-2012, 09:51 PM

Im curious as to what Fasttrack thinks.

Perhaps it is incomplete, and not incorrect.

Not in this case. This is an effect that it predicts but appears to predict incorrectly.

aostling

11-28-2012, 10:40 PM

Popular story:

http://www.nanowerk.com/news2/newsid=27724.php

The Popular story states

If 20 of titanium's 22 electrons are removed, it becomes a highly charged ion that looks in many ways like a helium atom that has been shrunk to a tenth its original size ..

I don't understand how the titanium ion can look smaller than a helium atom, since the Ti nucleus is larger than the He nucleus. Are they talking about the relative sizes of the electron clouds?

The actual size of the nucleus of an atom plays no part in the electromagnetic properties. It is the overall charge that matters. The "size" of an atom depends on its ionic radius. The more negative it is the larger the ionic radius and the more positive it is the smaller. An non-ionized helium atom has a particular ionic radius. A titanium atom missing 20 electrons is very strongly positive and so has a very small ionic radius. The positive ion has a stronger attraction on the remaining electrons so it pulls the electron shells closer. The negative ion has less unit attraction per electron (from the protons) so the shells expand, keeping in mind that the electrons repel each other and aren't subject to the strong force.

Bruce Griffing

11-29-2012, 12:12 AM

I am betting on QED. To even do the QED calculation you have to ignore many things. Your justification for doing so is the assumption that the ignored terms are small and do not contribute to the answer. These things are called perturbations by those who do the calculations. You can check to see that a given term is small enough to ignore, but it is at time hard to tell if you left anthing out. You have to account for all of the important perturbations to get the correct answer. So they may not have all of them present and accounted for. Another possibility is an interaction that QED does not account for at all. For example, QED does not take nuclear forces or gravity into account. If, for example, nuclear forces did make a difference in this case, QED is not wrong, it simply does not describe the details of this experiment. Time will tell, but QED has been called into question in the past, but it won out in the end.

Fasttrack

11-29-2012, 12:14 AM

I caught this thread early! Usually I miss the interesting threads until they hit 4 pages or longer...

The "popular story" and the press headlines are extremely misleading. In fact, the title of the PRL paper is the key to this conundrum:

Testing Three-Body Quantum Electrodynamics with Trapped Ti20+ Ions: Evidence for a Z-dependent Divergence Between Experiment and Calculation

(Emphasis added)

Three body QED is not an analytic theory. In fact, as an undergraduate, I worked on an experiment very similar to this one studying the three body problem in QED. About two years ago we found a divergent discrepancy between a popular theory and experiment for helium at very low energies that was published in PRL.

I think the quote from Jonathon Sapirstein (professor of physics at Notre Dame) is the best summary of these new results (snipped from the popular story):

"What the NIST experiment found is interesting enough that it merits attention. Independent calculations should be done to confirm the theory, and other experiments should also confirm the findings. However, if no errors are found in the theory and the NIST experiment is correct, some physics outside of QED must be present."

As Tony Ennis suggests, this may very well be a case of incompleteness and not incorrectness. What the popular article doesn't reveal is that this wasn't a test of QED but a test of our understanding of the three body problem in QED. At this level, it's not a matter of simply having a formula and plugging parameters in to get a result. Scattering in QED requires fairly sophisticated mathematics; mathematics beyond our normal algebra ... meaning that the objects in our formulas don't obey basic relations like AB = BA but may still be single objects (e.g. not matrices or tensors). For instance, one approach to the quantum field theory describing fermions (e.g. the electrons in this experiment!) requires the use of things called "Grassmann numbers", which are anti-commuting. If A and B are Grassmann numbers and X is a "normal" real number, then we have the following algebra:

AB = - BA

AX = XA

A^2 = 0

These are true for any Grassmann number and any real number.

Well that was a little diversion, but the point is ... the popular story over simplifies the problem with the result that it makes a somewhat extraordinary claim. Certainly, this is an exciting result, but it is not evidence that fundamental QED is incorrect.

Fasttrack

11-29-2012, 12:24 AM

I am betting on QED. To even do the QED calculation you have to ignore many things. Your justification for doing so is the assumption that the ignored terms are small and do not contribute to the answer. These things are called perturbations by those who do the calculations. You can check to see that a given term is small enough to ignore, but it is at time hard to tell if you left anthing out. You have to account for all of the important perturbations to get the correct answer. So they may not have all of them present and accounted for. Another possibility is an interaction that QED does not account for at all. For example, QED does not take nuclear forces or gravity into account. If, for example, nuclear forces did make a difference in this case, QED is not wrong, it simply does not describe the details of this experiment. Time will tell, but QED has been called into question in the past, but it won out in the end.

Very well said! Currently, I am working on a process known as VBF: "Vector Boson Fusion" which could provide us with a sensitive experimental test of the Standard Model by examining collisions in the ATLAS detector at the LHC. To make a long story short, there are many subtleties involved in these types of studies. Everything from gauge choice/invariance to interference to "perturbations". Typically, the precision is set by the number of perturbations you include but understanding the interference is where the real difficulty lies.

aostling

11-29-2012, 12:27 AM

A titanium atom missing 20 electrons is very strongly positive and so has a very small ionic radius.

Your explanation of atomic "size" makes the situation perfectly clear.

Now we await independent verification of the anomalous results. I wonder which would be a bigger scientific discovery -- the upcoming announcement of the Mars discovery, or this potential flaw in QED. These are heady times!

Fasttrack

11-29-2012, 01:03 AM

Now we await independent verification of the anomalous results. I wonder which would be a bigger scientific discovery -- the upcoming announcement of the Mars discovery, or this potential flaw in QED. These are heady times!

Anything discovered on Mars will likely be a bigger discovery than the results reported here. As I explained above, the popular story is extremely misleading. All you have to do is read the title of the paper. If you make it a little farther, read the last few lines of the abstract [Phys. Rev. Lett. 109, 153001 (2012)]:

Our result for titanium alone, 4749.85(7) eV for the w line, deviates from the most recent ab initio prediction by 3 times our experimental uncertainty and by more than 10 times the currently estimated uncertainty in the theoretical prediction.

An ab initio prediction is a particular "brand" of numerical or computational methods used to solve multi-body QED. The fact that the theory and experiment are in disagreement does not mean that QED is wrong but that the numeric method used to solve the equations generated by QED are not useful for this type of interaction. "Ab initio" refers to the fact that these methods can be tailored to converge to exact solutions (when we can calculate exact solutions!) when some very specific criteria are met. In short, it's just as Bruce Griffing said. It's not at all trivial to do these calculations. It is very likely that the method of calculation is not suitable for this experiment and it is very unlikely that the fundamental QED governing the interaction is incorrect.

I have difficulty seeing how there can be any equivalence between the 3 body problem at the macro scale and the quantum scale. It seems a bit misleading to even call them by a similar name. The fact that 3 body QED is not analytic and macro 3 body is also not analytic seems more a matter of coincidence (in actual fact there is a useless analytical solution to the regular 3 body problem, but not the general case).

Regardless, the result of the experiment is as I described and it remains to be seen if it can be verified with other elements. The authors state they have taken care to account for confounding factors and obviously there were no glaring errors seen upon peer review. We shall see. This experiment seems to be on much better ground than the faster than light neutrinos.

NASA has completely backed off from the earlier statement by the project leader. They are now saying the results will be "interesting" to those that follow the program.

An ab initio prediction is a particular "brand" of numerical or computational methods used to solve multi-body QED.

My understanding is that simply refers to a calculated set of beginning conditions as per QED (In this instance. It could be anything). The final conditions are then calculated based on the ab initio values and further inputs to determine the QED predictions. The experimental values are then compared.

beanbag

11-29-2012, 01:37 AM

Core electrons at low levels are responsible for cold fusion, you know?

"core electrons"??? (shakes head). Yes, I know its a joke.

Fasttrack

11-29-2012, 11:37 AM

I have difficulty seeing how there can be any equivalence between the 3 body problem at the macro scale and the quantum scale. It seems a bit misleading to even call them by a similar name. The fact that 3 body QED is not analytic and macro 3 body is also not analytic seems more a matter of coincidence (in actual fact there is a useless analytical solution to the regular 3 body problem, but not the general case).

Regardless, the result of the experiment is as I described and it remains to be seen if it can be verified with other elements. The authors state they have taken care to account for confounding factors and obviously there were no glaring errors seen upon peer review. We shall see. This experiment seems to be on much better ground than the faster than light neutrinos.

Who said anything about the classical three body problem? The fact that no analytic solution for the three body problem in QED is significant because it means we have to make a choice regarding how we calculate. There seems to be some major misconceptions about what QED is and how we use QED...

For those that do not have access to the paper, this is taken from the concluding remarks:

The evidence for systematically low predicted transition

energies suggests that missing terms in three-body QED

calculations are much larger than presently anticipated or

there is an error in the calculated terms.

I am not suggesting their experiment is flawed; I am suggesting the method of calculation is not applicable in this instance. The fact that a particular calculation method does not work is not evidence that QED is wrong. In fact, you may notice that they show their results compared to 3 different theories! This is an important result for physicists because it means we need to improve our tools for calculation but it does not imply anything about the fundamentals of QED.

The leading theory that is in disagreement with the experiment is presented in this paper:

http://pra.aps.org/abstract/PRA/v71/i6/e062104

If you wish the press the issue, the result of the experiment is NOT as you described it and I fail to see how this goes "directly to the heart of QED".

This person thinks a bit differently than you:

"What the NIST experiment found is interesting enough that it merits attention," says Jonathan Sapirstein, a professor of physics at the University of Notre Dame. "Independent calculations should be done to confirm the theory, and other experiments should also confirm the findings. However, if no errors are found in the theory and the NIST experiment is correct, some physics outside of QED must be present."

From the above "popular story" link.

"some physics outside of QED must be present" directly implies physics that QED should account for but doesn't.

Bruce Griffing

11-29-2012, 03:18 PM

It could simply mean that electroweak interactions between the electrons and the nucleus are important. This is reasonable, as the nucleus is a much larger fraction of the atomic size than would be the case for a neutral atom because the electron cloud is so small. The handwaving argument for this would be that the electrons wavefunction(s) has(ve) more overlap with the nucleus. I say handwaving because QED does not use a wavefunction approach. But electroweak interactions do constitute physics outside QED. As I said before, that does not make QED wrong. It is just an incomplete description of the problem at hand.

aostling

11-29-2012, 03:48 PM

It could simply mean that electroweak interactions between the electrons and the nucleus are important. This is reasonable, as the nucleus is a much larger fraction of the atomic size than would be the case for a neutral atom because the electron cloud is so small. The handwaving argument for this would be that the electrons wavefunction(s) has(ve) more overlap with the nucleus. I say handwaving because QED does not use a wavefunction approach. But electroweak interactions do constitute physics outside QED. As I said before, that does not make QED wrong. It is just an incomplete description of the problem at hand.

If electroweak interactions need to be considered, would a new encompassing theory have to be built up from scratch? Your comment implies that it would, since (as you say) QED uses a wavefront approach which is incompatible with a physics of the electroweak.

If Feynman is in heaven he must be looking down upon this with amusement.

Bruce Griffing

11-29-2012, 04:06 PM

QED is a theory that deals with electromagnetic interactions. That is its nature. If EW forces are at work, QED is not the appropriate choice for the calculation - not wrong, just inappropriate. The theory to explain a case that involves both EM and EW already exists, but a calculation of the effects being discussed would be very difficult. The theory provides rules to do the calculations, but applying those rules can be very difficult for a given case. BTW, I am not saying EW forces are sure to be important in this case, it is just a speculation. It could be, as I said earlier, the the QED calculation has some important terms missing.

Fasttrack

11-29-2012, 05:56 PM

This person thinks a bit differently than you:

From the above "popular story" link.

"some physics outside of QED must be present" directly implies physics that QED should account for but doesn't.

:rolleyes: That's the same quote I included in one of my first posts. What Sapirstein is referring to is not QED but in the theory - e.g. the calculation method - used to calculate the effect. This is abundantly in the paper. The experimental results are compared to several leading methods of calculation. If one of these calculations is indeed "correct", then physics outside of QED must be present. As Bruce Griffing has already stated, that does not mean that QED is, in any sense, "wrong". Furthermore, I have made the claim that the liklihood of the calculation being correct is pretty slim. Read the paper I posted on the paper describing the method of calculation for the leading theory. It agrees well with experiment formany situations but may lack the accuracy to deal with this situation for reasons not immediately obvious.

I guess we shall wait and see what they come up with. I went to NIST and there are hints that they have confirming results from experiments with other elements.

Fasttrack

11-29-2012, 06:25 PM

If electroweak interactions need to be considered, would a new encompassing theory have to be built up from scratch?

Nope! Bruce Griffing already answered your question, but I will add a few comments.

There are four fundamental forces: electromagnetc, weak, strong and gravity. Electroweak theory is a field theory similar to QED but accomplishes the unification between two of the fundamental forces. In another post, you demonstrated some knowledge of Noether's theorem. You may, therefore, be familiar with the notion of "gauge symmetries". This is a special kind of "continuous local symmetry". In essence, it's the same thing as adding a phase to a wavefunction. It doesn't change the physical results, in this case it leaves the action of the lagrangian invariant. (From Noether's theorem, we know that there must be a conserved quantity associated with these gauge transformations!)

Using the "phase" analogy, the choice of phase is known as a gauge choice and changing that choice is known as a gauge transformation. If the lagrangian is invariant under such transformations, than those transformations comprise something known as a "Lie group" or "gauge symmetry group". In the case of QED, the gauge symmetry group is abelian and unitary, called U(1). The weak symmetry group is known as a special unitary group and has the name SU(2). The unification of E&M and weak force is represented through the kronecker product of SU(2) and U(1) symmetry groups - called SU(2) "cross" U(1). It turns out that this new symmetry group isn't too unreasonable to work with and we can formulate a quantum field theory around it just as we did around QED.

See... QED is a subset of the QFT governing electroweak interactions which is, itself, a subset of the Standard Model.

Fasttrack

11-29-2012, 06:28 PM

I guess we shall wait and see what they come up with. I went to NIST and there are hints that they have confirming results from experiments with other elements.

That was mentioned in their paper as well. Like I said, I do not doubt the experimental results. In fact, the group I was working with as an undergraduate saw glimmers of this but our experiment was not sensitive enough (our results were on the same order of magnitude as our statistical error). The issue is not with the PRL paper but with the claim that this somehow is evidence that QED is wrong.

Error is the word I used. If it should predict the phenomenon and doesn't then it is an error. We shall find out.

beanbag

11-29-2012, 06:58 PM

I think this thread should be titled "Uh oh... Difficult and very approximate QED calculations that ignore other effects fail to match corner-case experimental results."

In other news:

"Bridge collapse blamed on engineer who used 10 instead of 9.8 for g"

In other but not necessarily unrelated news, we have this:

http://www2.warwick.ac.uk/newsandevents/pressreleases/graphite_experiment_shines/

However, the researchers found that rather than eliminating the gap between the model and the observed results the difference significantly increased. Their more precise experiment in fact shows that the equilibration of the temperatures for hot electron and cool ions is actually three times slower than previous measurements have shown and more than ten times slower than the mathematical model predicts. This means that the basic process of electron-ion interaction is only poorly understood.

loose nut

11-29-2012, 10:20 PM

Evan, even if the GED theory is proven to be wrong it isn't a bad thing.

Any time you think that you know everything there is to know about a theory you are wrong. When you find that a theory is wrong that is just the advancement of science. Disproving a theory is just as important as proving one if it leads you to the truth.

It has nothing to do with good or bad. It is all about interesting and what will be found as a result. All current theories dealing with physics are incomplete since none are able to explain all that we observe. It is when we find something that a current theory should explain but doesn't that it really becomes interesting. Then the current theory must either be extended to account for the observation or even discarded or reformulated. We are at a point where we understand a great deal about physics but not all. There are still many areas that need to be filled in. That may never happen. It has not been conclusively determined that there is a limit to the levels of structure underlying the structure of matter. Are quarks the bottom level? Many think so and there are strong arguments for it but not absolute arguments. We still cannot explain how galaxies are held together other than to say that "the dark matter did it". We don't yet have a coherent theory of "Dark Matter" and unless we do we won't have a complete theory of matter at all. Unless we can explain why gravity exists we won't have a complete theory of matter.

derekm

11-30-2012, 10:02 AM

This is all related to the philosophical issue of whether Physics is truth.I have always held that physics is not truth but a mechanism of predicting the future to a useful accuracy.

The maths is not reality, but a model that has a field of useful application.

QED model as implemented there is reaching its limits.

Deja Vu

11-30-2012, 10:50 AM

Nope! Bruce Griffing already answered your question, but I will add a few comments.

There are four fundamental forces: electromagnetc, weak, strong and gravity. Electroweak theory is a field theory similar to QED but accomplishes the unification between two of the fundamental forces. In another post, you demonstrated some knowledge of Noether's theorem. You may, therefore, be familiar with the notion of "gauge symmetries". This is a special kind of "continuous local symmetry". In essence, it's the same thing as adding a phase to a wavefunction. It doesn't change the physical results, in this case it leaves the action of the lagrangian invariant. (From Noether's theorem, we know that there must be a conserved quantity associated with these gauge transformations!)

Using the "phase" analogy, the choice of phase is known as a gauge choice and changing that choice is known as a gauge transformation. If the lagrangian is invariant under such transformations, than those transformations comprise something known as a "Lie group" or "gauge symmetry group". In the case of QED, the gauge symmetry group is abelian and unitary, called U(1). The weak symmetry group is known as a special unitary group and has the name SU(2). The unification of E&M and weak force is represented through the kronecker product of SU(2) and U(1) symmetry groups - called SU(2) "cross" U(1). It turns out that this new symmetry group isn't too unreasonable to work with and we can formulate a quantum field theory around it just as we did around QED.

See... QED is a subset of the QFT governing electroweak interactions which is, itself, a subset of the Standard Model.

So Fasttrack! Does this mean that if the data accumulated produces a deviation from the expected, as Evan mentioned below, it would clearly indicate that only another branch of theory would develop ? :confused:

You have said a mouthful above that goes beyond my meager immersion into the observations of those mentioned.

I can only appreciate your notes with an amazement that prompts me to include you with those other genuis's mentioned here and there. ;)

Fasttrack

11-30-2012, 11:04 AM

QED model as implemented there is reaching its limits.

No. There is absolutely no evidence that QED is "reaching its limits" or that it fails to predict anything. You'll forgive me for being rude, but there continues to be a gross misconception about what "QED" actually is or how it is implemented. There is no reason to believe that QED produces errors. There is very good experimental evidence to suggest that calculations derived from QED are incorrect. That is not the same as QED being incorrect or containing errors.

(I've removed special characters) From PHYSICAL REVIEW A 71, 062104 s 2005 d

... and signiﬁcantly improves the

theoretical accuracy for the energy values, especially in the

high-Z region. Unlike previous calculations, the results ob-

tained are complete through order ... ; uncalculated

terms enter through three-photon QED effects f to order

... and higher ... and through two-loop one-electron QED

corrections ... and higher ... .

(emphasis mine)

If you actually take the time to read the paper cited above, you will see that this is a common trend (as I already pointed out!). Theoreticians make a calculation that agrees well with established results. Experimentalists push the boundary and find that the calculation fails for certain, previously untested, situations. The calculation is performed again with a more careful evaluation of terms that were previously neglected or only estimated. The calculation is massaged back into agreement. The process repeats. The cited paper gives an in-depth summary of previous theoretical calculations and experimental data.

But don't take my word for it ... here it is from the original paper [PRL 109, 153001 (2012)]

While theZ^3 dependence is consistent with the expected

scaling of uncalculated screening corrections to the two-loop Lamb

shift (e.g., Ref. [32]), the magnitude is unexpectedly large.

Z^3 is the best phenomenological description of the divergence

given the present accumulated data. The origin of any divergence

between experiment and theory could be more complex, involving a

variety of QED effects, orders, and Z dependencies.

(emphasis mine)

Or perhaps you prefer this passage from the same paper:

Drake’s [2] pioneering comprehensive calculation of the

lowest few energy levels of all heliumlike ions from Z ¼ 2

to Z ¼ 100 using the uniﬁed approach has sufﬁcient accu-

racy that it has stood as a standard reference for decades.

More recently, several groups have built upon previous

work with a variety of methods for including additional

QED corrections to ever-higher orders. The work of

Artemyev et al. [26], for example, includes two-electron

QED corrections and is one of the most complete treat-

ments to date, so is presented as the reference theory in

Fig. 2(b). The theory results of Cheng and Chen [27] and

Plante et al. [28] are detailed relativistic conﬁguration

interaction and relativistic many-body perturbation theo-

retical treatments of He-like systems that cover the range

of mid- Z and are therefore included for comparison. These

three recent works are potential improvements upon

Drake’s calculation for Z > 15

(emphasis mine)

Again - the problem is not with QED but the calculations stemming from QED.

Fasttrack

11-30-2012, 11:25 AM

So Fasttrack! Does this mean that if the data accumulated produces a deviation from the expected, as Evan mentioned below, it would clearly indicate that only another branch of theory would develop ? :confused:

That's the misconception I've been fighting! :) Unfortunately, things in modern physics are never so simple as that. Unfortunately, I'm not coming up with any good analogies at the moment. See the problem isn't with the theory (or at least there is no reason to believe that there is a problem with the theory). The problem is in the calculations. In the simplest terms, I will liken it to a child doing arithmetic. Suppose he or she has a math test at school and the problem is 19+17 and the child answers "26". Now if we count out 19 objects in one group and 17 objects in another group and then count both groups together, we come up with 35 +/- 2 (Maybe I'm bad at counting ;) ). Now we have to decide whether there was a fundamental mistake in the counting or if the calculation of 19+17 was wrong. There is no reason, however, to conclude that the basic rules of arithmetic are incorrect or incomplete. The far more likely answer is that the person doing the calculating forgot to carry a "10".

Like I said, the calculations are not at all simple and require approximation methods, so even if there aren't basic arithmetic errors, there can be "errors" because we forgot or purposely neglected certain terms.

An example might be simple harmonic motion. We often make "small angle" approximations and neglect things of order angle^2 to get a nice, neat answer. However, when we push our experiments to the limit of what a "small angle" means, our solution diverges from reality. This isn't because there is some new physics that Newton's "laws" aren't predicting - even if we tackle the problem from the Hamiltonian level, we still have the same problem. The error rests in our choice of approximation. In fact, discrepancies in precision measurements even at small angles will be noted due to the fact that the Earth isn't a perfect inertial reference frame! So to do the problem at large angles and with a high degree of accuracy, we need to account for the motion of the Earth and retain terms of order angle^2. But we hit another problem - the formulation of the problem is now so messy that we can't solve it analytically so we have to invent a numeric method to solve the problem. Now we use this numeric approximation method and maybe it agrees but maybe it doesn't. If it doesn't, is it reasonable to assume that I just violated F=ma, or should I believe that there is either additional effects that I have neglected/my approximation method is flawed?

derekm

11-30-2012, 11:46 AM

No. There is absolutely no evidence that QED is "reaching its limits" or that it fails to predict anything. You'll forgive me for being rude, but there continues to be a gross ...

...

Again - the problem is not with QED but the calculations stemming from QED.

Whoa there I was agreeing, the agreement is in the "as implemented there" i.e their particular mathematical embodiment of theory has reached its limits.

I got used to doing physics where being within an order of magnitude or 2 was considered a bullseye

Fasttrack

11-30-2012, 11:52 AM

Whoa there I was agreeing, the agreement is in the "as implemented there" i.e their particular mathematical embodiment of theory has reached its limits.

I got used to doing physics where being within an order of magnitude or 2 was considered a bullseye

I'm sorry I misread your post. My post wasn't directed specifically at you. Just to clarify, the "you'll forgive me for being rude" was meant to be "you" plural, as in everyone reading my post but I realize now that it reads as though it were aimed specifically at you!

I was recently talking with a research advisor about perspective. He comes from precision physics background while I come from experimental high energy. I am currently working for him on a phenemonological study and we were laughing at how different we view things. For an experimentalist at the LHC, an order of magnitude really is a bullseye while he was used to dealing with 1 ppm type measurements.

aostling

11-30-2012, 12:35 PM

The far more likely answer is that the person doing the calculating forgot to carry a "10".

Well, then, they should have used a Curta.

I desperately wanted a Curta when I was a child but the cost was far beyond reach.

http://www.youtube.com/watch?v=HYsOi6L_Pw4

Fasttrack

11-30-2012, 12:54 PM

I desperately wanted a Curta when I was a child but the cost was far beyond reach.

http://www.youtube.com/watch?v=HYsOi6L_Pw4

Didn't you post a thread detailing the construction of these little gems? I never even knew they existed until you (or perhaps someone else) made a reference to them in thread.

beanbag

11-30-2012, 12:55 PM

you know whose fault it is... it's those dumb popular science articles that make mundane physics experiments out to be some groundbreaking new work.

Oh look, a new effect has been discovered in condensed matter systems... (where's that eye rolly emoticon?)

I don't recall posting about them but it is possible that I have forgotten a post or two. http://ixian.ca/pics9/biggrin.gif

That is an interesting video, BTW. Also, it provides some machining content...

Also, NASA has now completely disowned the earlier "earthshaking, one for the history books" comments and now says essentially nothing was found. Watch the conspiracy theorists take over this one.