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Experiment Shows Neutrinos Have Mass
Tuzanor writes: "Physicists have found the most convincing evidence yet that neutrinos, subatomic particles that were thought to have no mass whatsoever, actually do have a very tiny mass after all. The story is at Yahoo!" We mentioned the experiment yesterday, but this is big news. The New York Times has a thorough article on the whole experiment and its meaning.
Okay, I'm a creationist (yeah yeah, go ahead and flame me) and this is why I have problems with a lot of science. This is just another example of them teaching something as fact and then finding out that they were wrong and throwing it away and replacing it with something else. It seems to me that alot of scientists just use a theory until they find something that works better and then they throw away the old one without admitting that they were wrong, or apologizing for it.
This is why I am convinced of creationism. Note that I am not being judgemental, I don't look down on people who don't believe, it's a personal thing that you will have to discover for yourself. But for me, I prefer a little bit of eternal truth instead of "approximations" of truth that change year by year and day by day, and are put forth by people who say that they aren't sure if they're right or not, and that the theories could change by tomorrow. Again I'm not bashing science or evolutionists, just trying to get people to think a bit.
neutrinons react via the weak force and there is nothing you can do to increase their reaction rate other than give them a more dense medium. Currently, the only practical way of detecting neutrinos is to use huge water tanks, place germanium photo detectors everywhere in the tank, and wait for "flashes". When a nuetrino reacts with one of the water(H2O) molecules, a photon will be given off which a germanium detector can easily see. Oh yeah, like I said above, The fact that Neutrinos have mass is ancient news. People need to crawl out from under their rock and smell the air.
I know that this is severely off-topic, I shouldn't even reply to this obvious flamebait, but I've got to jump in here. This poster is making the claim (that is made repeatedly by so-called "Christians") that socialists and other people who are on the left end of the political spectrum are necessarily irreligious. This is an outright lie, and there is a systematic campaign to spread it. The Christian Left is not as active as it once was, having been mercilessly attacked by the well-financed "Christian" Right. But that doesn't mean that it doesn't exist. If you're interested I would invite you to visit the following link:
.. two things that are about as diametrically opposed to each other as is possible.
Liberals Like Christ
The fascination that the right-wing "Christians" of today have with money can be traced back to the Cold War. It is an unfortunate relic of the blind McCarthyist hatred of communism and of the Soviet Union in particular. It caused people to gravitate towards the extremist Ayn Rand-type of capitalism, and it manifests itself today with the worship of money and the hatred of the poor that is so common among those who claim to part of the "Christian" Right. These people have become blinded by their prejudices and are allow themselves to confuse GOD with the GOP
People who want restrictions lifted to allow rich people to make as much money as possible cannot claim to follow a Scripture which teaches that the love of money is the root of all evil. People who hate socialists and love cold, hard cash cannot claim to worship He who came into the temple and threw out the money-changers. "Dearly loved friends, don't always believe everything you hear just because somebody says it is a message from God: test it first to see if it really is. For there are many false teachers around (the Republican Party.)" -- 1 John 4:1.
First, it must be pointed out that neutrino masses can be added without serious violence to the Standard Model of particle physics. There is no good theoretical reason for them to be massless, as there is for photons (something important called "gauge symmetry"), and in fact, there are various proposed extensions of the Standard Model like the "seesaw model" that can easily produce appropriate neutrino masses.
As to neutrino oscillations and where they come from, it takes a bit of Quantum Mechanics. There are at least three types of neutrino field, which can be mixed in various ways to produce various kinds of neutrino states. One kind of mixture produces the mass states, while another kind of mixture produces the weak states (neutrino from electron, neutron from muon, neutrino from tau). Beta decays will produce the neutrino-from-electron mixture, but that will be a mixture of the neutrino mass states. Due to their masses, these mass states will oscillate out of phase, making the combination some mixture of the various weak states. Meaning that what started out as an electron neutrino could end up partially a muon one or a tau one, and those latter ones will be hard to see with an inverse-beta-decay detector, because muons and taus are much more massive than electrons.
However, this oscillation takes time to happen, and traveling from the Sun takes much more time than traveling across a lab, which is why the effect is much more noticeable in neutrinos coming from the Sun than produced in a lab.
Finally, it must be noted that news-media coverage of research is slanted to sensationalism, and overturning previous theories is certainly a sensational thing to happen. But what has really happened in many cases is that new theories build on old theories, often including old theories as special cases. Thus, Newtonian physics becomes a special case of Einsteinian physics and classical mechanics a special case of quantum mechanics. In fact, such special-casing is a necessity because a new theory must explain why a successful old theory has been successful. So "scientific revolutions" and "paradigm shifts" have been overrated.
It sounds good, but this doesn't 100% jive with other experimentation and the theory of what we call the "neutrino".
l i.html
Back around 1993, John Edwards, et al, came to the conclusion that neutrinos have no mass after a 10 year, $100 million neutrino mass experiment funded by the nuclear energy commission.
The theory still holds that a neutrino with a detectable mass significantly smaller than the new clamined mass would in fact be detected in the apparatus. The apparatus used
for mass detection was, in terms of mass detection, more accurate to the one described in the article above.
A possible explaination is that Neutrinos sometimes have mass.
But it is more likely that there are two types of "neutrinos", one rare type with mass (so called mneutrinos), and one much more common type without mass (neutrinos). The theory behind each are very very different!
For more information, see http://www.autodynamics.org/new99/Neutrino/NeutDe
http://k2k.physics.sunysb.edu/k2k/
http://www.hep.anl.gov/ndk/hypertext/numi.html
Neutrinos have mass.
Now I can sleep.
Now I can spend my days
loving you up.
Neutrinos have mass.
Now I can sleep.
Suddenly the veil has been lifted.
--
Forget Napster. Why not really break the law?
"Remember when the U.S. had a drug problem, and then we declared a War On Drugs, and now you can't buy drugs anymore?"
Well, there goes "Dark Matter"!
It's nice to see something interesting done in Sudbury, Ontario, Canada, previously only know for a Giant Canadian Nickle.
ttyl
Farrell
CAN-CON 2019 - Ottawa's only book oriented Science Fiction Convention! October 18-20, Sheraton Hotel, Ottawa, Canada h
I have so much crap on my desk as it is. Now you tell me I have more?!?
My mom always said, "Jim, you're 1 in a million." Given the current population, there are 7000 of me. God help us all!
Here in the South (Austin, TX, anyway), it seems pretty common to use the word "jive" in place of "jibe." This is for two reasons, 1) standard linguistics... 'b' corrupts to 'v' and 2) the meaning of "jive" which is "to swing" (think Swing dancing) bears a connotation of mutual agreement. Thus, the two things in question dance together, they swing, they jive.
This defense brought to by the guy who is trying to explain to his 5 year old that "ain't", as used by his redneck mother, is less acceptable than "isn't" or "aren't".
cheers,
-l
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When an electron neutrino transforms into another type of neutrino, could they be said to "decay" into the other neutrino?
Or is a neutrino transformation more similar to when an excited electron falls to a lower energy state, giving off a photon in the process?
Or are neither of these analogies appropriate?
That that is is that that that that is not is not.
Few physicists thought neutrinos had mass... but since that paradigm seems to have been broken, might there be a remote chance that photons also have a wee bit of rest mass? Maybe photons travel at (1 - 10^-100000000)c, not c. Maybe nothing travels at c.
That that is is that that that that is not is not.
Sorry I'd have to correct you there - SR states that if something has *rest mass* then it can't travel at the speed of light. If it's moving, then it must have mass as it has an energy.
That's true, but why we're discussing SR when the article is involving rewriting important parts of QM is beyond me. :-)
Still, this will stop people from making silly assertions about black holes in the centre of the Sun and so on.
The largest part of the 'mass' (energy) of the neutrino still comes from its kinetic energy. What has been found in the experiment is that it also has a *rest* mass (ie. a mass at zero velocity).
Maybe they invent particles to make their theories look good - said theories having been proposed vaguely enough to encompass almost anything - then coalesce the theories down around the data as it arrives, calling anything which doesn't fit ``anomalous'' (note the perspective: reality doesn't fit the theory, so reality must be the anomaly, not theory!), then either delete the few offending data from their datasets because it's anomalous, or occasionally when it can't be swept under the carpet, declare it to be a great and rare mystery then set about making a special-case patch to the theory in the hope of eventually having it all work.
Want a clear, real-world example of this? Try radio-isotope dating.
Got time? Spend some of it coding or testing
...shielding it from cosmic radiation would be a problem.
The only obvious way to shield is very expensive: use several, and go mining on Mercury and maybe Mars (both totally hostile environments) to bury many tonnes of delicate instruments a mile or so down. I'd like to see the budget for that!
Got time? Spend some of it coding or testing
Yah, that does explain a lot more. And here's another with a slightly different angle.
Uh, I think that would be ``reframing an observation.'' There's no shortage of exciting and imaginitive - and, unfortunately, bankrupt - explanations proposed for ``anomalies'' in orthodox theories, rather than cleanly rewriting the theories as should be done. Just ask J Harlan Bretz about that.
Got time? Spend some of it coding or testing
Just because physically observed particles have mass, it is not necessarily required that the theory has particle masses in its bare Lagrangian form from which the perturbation theory Feynman rules are determined. (And I'm not talking about the Standard Model's Higgs Mechanism for mass generation by spontaneous symmetry breaking - which is another thing altogether...)
Non-perturbative calculations using the Schwinger-Dyson equations, Ward identities and renormalisability constraints show that masses can be generated dynamically through interactions of massless fields.
Some (8-10 year old) references can be found via this HEPDATA query. Note that this is not talking directly about neutrinos, but rather about generating masses for electrons in a simplified version of QED in which electrons start out massless.
There are almost certainly some newer papers that you could find either at HEPDATA or SPIRES.
(Full Disclosure: Mike Pennington was my Ph.D. Supervisor, although I didn't work in the non-perturbative SD equations field myself except for a short while at the start)
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In supernova 1987, the neutrino pulse was only
seconds before the radiation brightening.
Not much notice.
If neutrinos have mass, they'd travel a little
slower than the speed of light. So you'd expect
some delays in that 1987 was about 150K light
years away.
--
I hope we shall crush in its birth the aristocracy of our monied corporations
And I'd be a Libertarian, if they weren't all a bunch of tax-dodging professional whiners.
Berke Breathed
Yes. Various astrophysical processes (and even some accelerators) create protons and electrons (and more exoctic languages) that have kinetic energies 1000 times their rest mass.
...
--
I hope we shall crush in its birth the aristocracy of our monied corporations
And I'd be a Libertarian, if they weren't all a bunch of tax-dodging professional whiners.
Berke Breathed
Right. I was thinking in terms of the stricter definition of essentially c (gamma = 1000), but that definition is probably too strict. Of course, the most interesting stuff moving near c is cosmic rays. Energies above 10^22 eV - that's fast.
...
--
I hope we shall crush in its birth the aristocracy of our monied corporations
And I'd be a Libertarian, if they weren't all a bunch of tax-dodging professional whiners.
Berke Breathed
Even if you could get low energy neutrinos ( less than an eV), you'd still have to collimate a beam them. That would be very difficult to do, since they react so little.
So yeah, its not impossible to measure the mass of a neutrino directly. But I'd be very surprised if we find a direct way to measure the mass of a neutrino anytime soon. Indirect will have to be good enough for a while.
...
--
I hope we shall crush in its birth the aristocracy of our monied corporations
And I'd be a Libertarian, if they weren't all a bunch of tax-dodging professional whiners.
Berke Breathed
So, neutrinos don't travel at c, but its pretty darn close.
...
--
I hope we shall crush in its birth the aristocracy of our monied corporations
And I'd be a Libertarian, if they weren't all a bunch of tax-dodging professional whiners.
Berke Breathed
Anyone care to elucidate on this part?
Mark Prindle, the most underappreciated genius on the web.
Neutrinos have a little mass, so they can't be quite moving at the speed of light. Therefore, when we see a Supernova go off, the light ought to arrive a little ahead of the neutrino burst.
As I recall, on the big, nearby Supernova 1987A, a neutrino burst was detected. My question is, did anyone get the timing nailed down from this event well enough toconfirm that the neutrinos were a little late?
Helium balloons want to be free.
Hey, you with from John? I did some work on SKAT 2 years ago for him.
"When you sit with a nice girl for two hours, it seems like two minutes. When you sit on a hot stove for two minutes, it
I had an office two doors down (Abby Normal). I did work in the lab accross his office th summer before SKAT got shipped to SuperK.
"When you sit with a nice girl for two hours, it seems like two minutes. When you sit on a hot stove for two minutes, it
Yes and no. This is a new story, making the front pages of newspapers here in Toronto. But apparently others have claimed to have proved that neutrinos have mass before now. Perhaps the findings of the previous experiment were not known, or discounted.
Sure, but we ignore relativity when doing simple physics in high school, pretending that F = m*a, and that mass, length and time are all constants. The fact is, for the most part Newtonian mechanics are pretty much correct, even if they're mathematically wrong. The equations are just simpler if the speed of light isn't a limit.
Actualy they aren't affected by gravity, gravity distorts the space-time. In a distordet space the photon then go strait ahead but since the space is curved the direction of "strait ahead" is a curve. Do you follow? I'm not shure if I am being clear enouth.
Imagine a strait line on the surface of the earth, say going from new york to Rio de Janeiro. This line is a curve, but at the same time is a strit line when you are locked to surface of a sphere (in this case earth). Masses in the universes create the same effect but in more dimentions.
--
"take the red pill and you stay in wonderland and I'll show you how deep the rabbit hole goes"
[]'s Victor Bogado da Silva Lins
^[:wq
EEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE!
This is a test of the Supernova Early Warning System. This is only a test. If there had been an actual supernova within a hundred light years of Earth, you would have been instructed to...
Ummmm...
PHEM - party like it's 1997-2003!
Cramer quotes an anonymous source as saying that if the sign of these numbers had been reversed (positive instead of negative), there would have been a big press conference announcing that they had shown the neutrino to have a nonzero rest mass.
I sent email to Cramer maybe five years or so later, asking what had happened with these results. He told me that nothing had happened; there has been no followup, and nobody has shown them to be wrong.
The super-Kamiokande experiment seems to have been carefully designed to show nonzero rest mass for at least one kind of neutrino while yielding no information on the actual value of the squared rest mass (in particular, its sign.) This experiment measured only the difference in squared rest masses between two types of neutrinos. (If this difference is nonzero, then one of the two neutrino types must have a nonzero squared rest mass.) It is consistent with either a positive or negative squared rest mass.
This latest result also carefully avoids the issue of the actual value (and sign) of the squared rest mass. It appears that everybody wants to get their Nobel for showing that the neutrino has a nonzero rest mass, but nobody wants to be labeled as a crank for presenting data that would indicate the neutrino has an imaginary rest mass!
If I remember right, massless particles, like photons, travel at the speed of light, and so neutrinos, when they were believed to be massless, must have traveled at the speed of light. Now, presumably they travel a little slower, right? I saw a TV documentary about the recent Supernova detected in the Large Magellanic Cloud, and one of the things the astro-physicists were really happy about was that a wave of neutrinos was detected passing through earth at just the right time. What gives? How fast do neutrinos travel or is my knowledge of physics wrong and out of date.
In theory, theory and practice are the same; in practice they're different. (Yogi Berra & A. Einstein)
They can't even make a decent beer.
Can't make a decent beer? Try Sleeman's or Granville Island Brewery or some other microbrew. Hell, even Kokanee isn't too bad.
I can't believe that someone from the United States, home of beer with alcohol content so low it has to be expressed in scientific notation, is insulting Canadian beer.
I find it hard to believe that Canada has the scientific know how to be trusted
In certain areas, such as some types of condensed matter physics (Mu-SR, beta-NMR), superconductor research, and some other fields, Canada leads the world. Our research programs are not as large as the US (since we're a smaller country, population-wise), but they're top-notch.
Uh, first of all, which U of A? The University of Alberta is also known as the U of A, and it's definitely in Canada. I'm guessing that's not the one you mean.
At UBC, Dr. Hardy's lab grows the world's highest-quality YBCO superconductors in the world. (YBCO is the common abbreviation for them--yes, I know the proper name, but it's too ugly in HTML). He is part of a larger Superconductivity Research Group at the University of British Columbia. That group also works closely with the Muon Spin Rotation Group based at UBC and nearby TRIUMF. Disclaimer: I'm part of the Muon Spin Rotation Group.
We're also in the process of commissioning a Beta-Nuclear Magnetic Resonance apparatus and beamline at TRIUMF, which will be very useful for probes of the local magnetic fields within superconductors (and other condensed matter physics applications).
This is by no means an exhaustive list of the areas in which Canada leads in physics--it's just what I'm familiar with. I know we also recently opened a (privately funded) institute for theoretical physics, and they pay very generous salaries. We've also managed to recruit a few key quantum computing people up from the US.
I'm not trying to say Canada is the best in the world at everything, but we do have some very solid, well-respected programs in physics.
Is this the same Dr. Hardy who was at the U of Arkansas about ten years ago working with Dr. Sheng? If it is, and I'm not saying it is, I always got the impression that he was a public relations guy and Sheng was the real horsepower.
Nope. Hardy has been at UBC for decades, and has won a shitload of awards. Take a look at his bio, which I linked to in my last message. Also, producing highest-Tc superconductors is mostly a game right now, since it's all very small incremental improvements. The real research involves growing and studying high-quality single-crystal samples to learn how they work, so we can make the next big leap. That's where Canada leads.
We take hold of a warm object, for example. The scientist will tell us: What
you are calling the heat or warmth is the effect on your own nerves.
Objectively, there is the movement of molecules and atoms. These you can
study, after the laws of mechanics. So then they study the laws of
mechanics, of atoms and molecules; indeed, for a long time they imagined
that by so doing they would at last contrive to explain all the phenomena of
Nature. Today, of course, this hope is rather shaken. But even if we do
press forward to the atom with our thinking, even then we shall have to ask
-- and seek the answer by experiment -- How are the forces in the atom? How
does the mass reveal itself in its effects, -- how does it work? And if you
put this question, you must ask again: How will you recognize it? You can
only recognize the mass by its effects.
The customary way is to recognize the smallest unit bearer of mechanical
force by its effect, in answering this question: If such a particle brings
another minute particle -- say, a minute particle of matter weighing one
gramme -- into movement, there must he some force proceeding from the matter
in the one, which brings the other into movement. If then the given mass
brings the other mass, weighing one gramme, into movement in such a way that
the latter goes a centimetre a second faster in each successive second, the
former mass will have exerted a certain force. This force we are accustomed
to regard as a kind of universal unit. If we are then able to say of some
force that it is so many times greater than the force needed to make a
gramme go a centimetre a second quicker every second, we know the ratio
between the force in question and the chosen universal unit. If we express
it as a weight, it is 0.001019 grammes' weight. Indeed, to express what this
kind of force involves, we must have recourse to the balance -- the
weighing-machine. The unit force is equivalent to the downward thrust that
comes into play when 0.001019 grammes are being weighed. So then I have to
express myself in terms of something very outwardly real if I want to
approach what is called "mass" in this Universe. Howsoever I may think it
out, I can only express the concept "mass" by introducing what I get to know
in quite external ways, namely a weight. In the last resort, it is by a
weight that I express the mass, and even if I then go on to atomize it, I
still express it by a weight.
I have reminded you of all this, in order clearly to describe the point at
which we pass, from what can still be determined "a priori", into the realm
of real Nature. We need to be very clear on this point. The truths of
arithmetic, geometry and kinematics, -- these we undoubtedly determine apart
from external Nature. But we must also be clear, to what extent these truths
are applicable to that which meets us, in effect, from quite another side --
and, to begin with, in mechanics. Not till we get to mechanics, have we the
content of what we call "phenomenon of Nature".
All this was clear to Goethe. Only where we pass on from kinematics to
mechanics can we begin to speak at all of natural phenomena. Aware as he was
of this, he knew what is the only possible relation of Mathematics to
Natural Science, though Mathematics be ever so idolized even for this domain
of knowledge.
To bring this home, I will adduce one more example. Even as we may think of
the unit element, for the effects of Force in Nature, as a minute atom-like
body which would be able to impart an acceleration of a centimetre per
second per second to a gramme-weight, so too with every manifestation of
Force, we shall be able to say that the force proceeds from one direction
and works towards another. Thus we may well grow accustomed -- for all the
workings of Nature -- always to look for the points from which the forces
proceed. Precisely this has grown habitual, nay dominant, in Science. Indeed
in many instances we really find it so. There are whole fields of phenomena
which we can thus refer to the points from which the forces, dominating the
phenomena, proceed. We therefore call such forces "centric forces", inasmuch
as they always issue from point-centres. It is indeed right to think of
centric forces wherever we can find so many single points from which quite
definite forces, dominating a given field of phenomena, proceed. Now need
the forces always come into play. It may well be that the point-centre in
question only bears in it the possibility, the potentiality as it were, for
such a play of forces to arise, whereas the forces do not actually come into
play until the requisite conditions are fulfilled in the surrounding sphere.
We shall have instances of this during the next few days. It is as though
forces were concentrated at the points in question, -- forces however that
are not yet in action. Only when we bring about the necessary conditions,
will they call forth actual phenomena in their surroundings. Yet we must
recognize that in such point or space forces are concentrated, able
potentially to work on their environment.
This in effect is what we always look for, when speaking of the World in
terms of Physics. All physical research amounts to this: we follow up the
centric forces to their centres; we try to find the points from which
effects can issue, For this kind of effect in Nature, we ate obliged to
assume that there are centres, charged as it were with possibilities of
action in certain directions. And we have sundry means of measuring these
possibilities of action; we can express in stated measures, how strongly
such a point or centre has the potentiality of working. Speaking in general
terms, we call the measure of a force thus centred and concentrated a
"potential" or "potential force". In studying these effects of Nature we
then have to trace the potentials of the centric forces, -- so we may
formulate it. We look for centres which we then investigate as sources of
potential forces.
Such, in effect, is the line taken by that school of Science which is at
pains to express everything in mechanical terms. It looks for centric forces
and their potentials. In this respect our need will be to take one essential
step -- out into actual Nature -- whereby we shall grow fully conscious of the
fact: You cannot possibly understand any phenomenon in which Life plays a
part if you restrict yourself to this method, looking only for the
potentials of centric forces. Say you were studying the play of forces in an
animal or vegetable embryo or germ-cell; with this method you would never
find your way. No doubt it seems an ultimate ideal to the Science of today,
to understand even organic phenomena in terms of potentials, of centric
forces of some kind. It will be the dawn of a new world-conception in this
realm when it is recognized that the thing cannot be done in this way,
Phenomena in which Life is working can never be understood in terms of
centric forces. Why, in effect, -- why not? Diagrammatically, let us here
imagine that we are setting out to study transient, living phenomena of
Nature in terms of Physics. We look for centres, -- to study the potential
effects that may go out from such centres. Suppose we find the effect. If I
now calculate the potentials, say for the three points a, b and c, I find
that a will work thus and thus on A, B and C, or c on A', B' and C'; and so
on. I should thus get a notion of how the integral effects will be, in a
certain sphere, subject to the potentials of such and such centric forces.
Yet in this way I could never explain any process involving Life. In effect,
the forces that are essential to a living thing have no potential; they are
not centric forces. If at a given point d you tried to trace the physical
effects due to the influences of a, b and c, you would indeed be referring
to the effects to centric forces, and you could do so. But if you want to
study the effects of Life you can never do this. For these effects, there
are no centres such as a or b or c. Here you will only take the right
direction with your thinking when you speak thus: Say that at d there is
something alive. I look for the forces to which the life is subject. I shall
not find them in a, nor in b, nor in c, nor when I go still farther out. I
only find them when as it were I go to the very ends of the world -- and,
what is more, to the entire circumference at once. Taking my start from d, I
should have to go to the outermost ends of the Universe and imagine forces
to the working inward from the spherical circumference from all sides,
forces which in their interplay unite in d. It is the very opposite of the
centric forces with their potentials. How to calculate a potential for what
works inward from all sides, from the infinitudes of space? In the attempt,
I should have to dismember the forces; one total force would have to be
divided into ever smaller portions. Then I should get nearer and nearer the
edge of the World: -- the force would be completely sundered, and so would
all my calculation. Here in effect it is not centric forces; it is cosmic,
universal forces that are at work. Here, calculation ceases.
Once more, you have the leap -- the leap, this time, from that in Nature
which is not alive to that which is. In the investigation of Nature we shall
only find our way aright if we know what the leap is from Kinematics to
Mechanics, and again what the leap is from external, inorganic Nature into
those realms that are no longer accessible to calculation, -- where every
attempted calculation breaks asunder and every potential is dissolved away.
This second leap will take us from external inorganic Nature into living
Nature, and we must realize that calculation ceases where we want to
understand what is alive.
Rudolf Steiner, Light Course, Lecture 1, Stuttgart, 23rd December 1919.
http://wn.elib.com/Steiner/Lectures/LightCrse/1
--
regards,
johnRpenner.
-------
Caimlas
~/ssh slashdot.org ssh: connect to host slashdot.org port 22: too many beers
For solar neutrinos this would be the case. However, development of a "neutrino spectrometer", a machine that made an accurate estimate of the energy of a neutrino would allow the speed be calibrated. If a burst of neutrinos was detected from a source at a known distance, then the delay between the initial higher energy neutrinos and the arrival of later neutrinos could be measured. A source sufficiently bright (to allow a detectable flux of neutrinos at our detector) and sufficiently far away (to allow this dispersion to occur) would allow such a small velocity difference be calculated. And for those who say it cant be done, similar effects in the x-ray spectrum allow the refractive index of intergalactic space be measured. (Or theoretically allow it to be done - this was a question on one of our physics papers, never found out whether anyone has actually done it!)
Hey, thanks for the summary. Interesting stuff.
:-) (I gather it's some kind of multidimensional matrix-like thingy.)
Now I just need to find out what a tensor is.
--
Patrick Doyle
I mod down every jackass who puts his moderation policy in his sig. Oh, wait a sec....
Incidentally, you can use "x²" to represent "^2", so it looks like this: "4r/T". Likewise for "³". Of course, I'm not sure what that does for Lynx users.
--
Patrick Doyle
I mod down every jackass who puts his moderation policy in his sig. Oh, wait a sec....
--
Patrick Doyle
I mod down every jackass who puts his moderation policy in his sig. Oh, wait a sec....
Are you sure that's sqrt(r)? I thought the square of the period was proportional to the cube of the distance. That would make it r^(-3/2).
--
Patrick Doyle
I mod down every jackass who puts his moderation policy in his sig. Oh, wait a sec....
Good explanation. Thanks!
Tom Swiss | the infamous tms | http://www.infamous.net/
Tom Swiss | the infamous tms | my blog
You cannot wash away blood with blood
So this this mean that:
Please, some physics geek tell us how to resolve "neutrinos has mass" with "neutrinos travel at c.
Tom Swiss | the infamous tms | http://www.infamous.net/
Tom Swiss | the infamous tms | my blog
You cannot wash away blood with blood
I've heard about records for high temperature superconductors from Japan (initially discovered high temp superconductors, I believe), Dr. Sheng (held the world record for high temp sc (via Y1Ba2Ca2Cu3Ox) for 5 years) and from France, but I've not heard anything about Canada.
Bobby Martin aka Wurp
Cosm Development Team
Is this the same Dr. Hardy who was at the U of Arkansas about ten years ago working with Dr. Sheng? If it is, and I'm not saying it is, I always got the impression that he was a public relations guy and Sheng was the real horsepower. He left for a higher paying job, I thought in Colorado, but I have no idea where he would be now. He was a big trumpet player (I think, one of those t-word horns : )
Again, I don't doubt that Canada leads the way in various physics programs, it was just the 'leads the world in superconductor research' that threw me off. It wasn't one of the names that I heard when I was in the biz.
Bobby Martin aka Wurp
Cosm Development Team
Great, all I need is a piece of lead several light-years thick, and I can then melt it down and extract the at-rest neutrinos to make neutrinonium (as long as I'm fantasizing, I wonder if a lump composed of neutrinos at rest would shimmer or somehow change color as the component neutrinos oscillated between three states ;-)
(Seriously, mad props to the SNO guys. I remember hearing about the Solar Neutrino Problem years ago, and hoping that Sudbury would get the funding to actually carry the experiment through to its conclusion.)
Karma whore!
You quoted a few bits of the article, and all the brainless moderators mark it Informative when in fact it should be Redundant because it doesn't contain anything new. Argh!
Other such particles include the IRCrumouron, and the GWBushbraincellon (the effects of whose such rapid departure have been observed recently)
The sun produces only one type of neutrino. But there are two other kinds that the earliest neutrino detectors could not see, and some of the ones made by the sun turn into those other types on their way to Earth.
How do they know that? I mean how do they know what type of neutrinos are coming out of the sun since their detectors are on the earth?
Thanks to everyone who responded to my query. I guess my problem is that the standard model is said to be somewhat flawed because it not only failed to predict the mass of the neutrino, it also failed predict whether or not the neutrino has any mass. Yet physicists seem confident that the model is good enough to predict that only massive particles can change type in transit and that the sun can only emit electron type neutrinos. I don't know about others but there seems to be a catch-22 whereby a partially flawed model is used to detect its own flaw. Maybe one of you can explain the reason why there is such a high confidence in one facet of the standard model and not the other.
Ok. Thanks for the reply. If neutrinos have mass they should travel at different speeds and even come to relative rest. There is no reason to suppose they always have to travel as fast as they do. Why do they appear to always travel at c?
Yeah, SNO is definitely playing this up more than it should. We've known that some neutrinos have mass since Super-K - specifically that there was a mass difference between muon and tau neutrinos.
However, there had been no direct evidence for oscillations of electron neutrinos, which are the neutrinos produced by the sun and which are by far the most numerous neutrinos in the universe. The number of electron neutrinos detected from the sun was 1/3 of what solar models predicted. The SNO result shows that the total number of neutrinos of all flavours coming from the sun matches the solar models, and so the other 2/3 that were missing are oscillating into other flavours. So there must be a mass splitting between electron neutrinos and whatever neutrinos they're oscillating into. Therefore, those neutrinos must have mass.
So this is a new and significant result, but this is not the first direct piece of evidence for neutrino mass.
[TMB]
I need some more convincing that neutrinos are changing on their way to Earth. A good way to give more credence to this idea would be to place both types of detectors at several points in the solar system and actually determine a rate factor.
Maybe Dubya could unificate the world to put some of these "new treeno" detectors up in the sky.
Finally, a Slashdot article that carries some weight!
Can you imagine the gravity of this situation?
Give me my freedom, and I'll take care of my own security, thank you.
However, it is funny they had to go all the way to Canada to find such conditions the US has more than it share of denuded, polluted, and generally f***ed up industrial sites.
Ummmm ... the way you stated that is less than precise.
...
For your second question:
E = m c^2 was not confirmed by Mercury's orbit. Deviations in Mercury's orbit from Newtonian predictions provided supporting evidence for Einstein's theory of general relativity.
E = m c^2 is not even correct (E = m c^2 for you only if the particle is at rest in your frame, provided your frame is inertial). E = m c^2 came from special relativity. Special relativity has been validated in many many ways (the energy yield of nuclear weapons to name a dramatic example).
Regarding your first question, the precise answer:
The gravitational Einstein curvature tensor at a point in space-time is proportional to the stress energy tensor at that same point in space-time (with an additive term for the local metric tensor if you are into the cosmological constant).
What does that mean?
Neglecting the stuff about the cosmological constant (the differential geometry equivalent to a constant of integration), regions with a higher energy density generate a stronger gravitational field.
Contributions to the stress energy at a point in space-time include rest mass density (i.e. air makes less curvature that steel), pressure (higher temperatures --> faster random motion --> more energy), electromagnetic fields (the photon radiation spectrum contributes to the tensor),
An issue of some contention is whether or not the gravitational curvature contributes to the stress energy tensor. Einstein thought it would be double counting but others are not so sure.
Most of the time (i.e. on earth), only the rest mass density is significant and Einstein's theory simplifies to Newtonian gravity.
However, in the core of a neutron star for instance, the contribution to the T_tt component of the stress energy from the pressure makes a significant contribution and needs to be accounted for.
Similarly, when accounting for the gravitional curvature due to say a black body radiation spectrum of photons, all the gravitional curvature comes from relativistic effects. Photons have no rest mass (more precisely, experimentally, photons have such a small rest mass as to make neutrinos look extra beefy); look up the equation of state for an extremely relativitistic ideal gas to get an idea of how photons contribute to gravitation.
A good resource for these things at a level beyond high school physics might be P. J. E. Peebles "Introduction to Modern Cosmology". It is often used as a text in advanced undergradute, intro graduate level courses in astrophysics.
But what do I know? After all, it is late into the thread.
Kevin
With that "logic", photons would have mass to, right?
With that "logic", photons would have mass too, right?
If I remember back to high school physics that means the universe is "closed" and there is gunna be a big crunch. I think that means we are screwed(in avery eventual sense) Can anyone correct or confirm this?
The Borg assimilated my race & all I got was this lousy T-shirt
What kind of mass are they talking about? The mass at rest (m0) or the mass due to kinetic energy (m=E/c^2)? (A photon has only the latter)
Opus: the Swiss army knife of audio codec
Not only that, but the different neutrino flavours must have different masses in order to oscillate.
But what's REALLY exciting, is they'll probably figure out how to use this in the first episode of Star Trek Enterprise as some sort of new kind of weapon or something.
"Lieutenant, fire the Neutrino Cannon!!!"
"I am sir, but it doesn't seem to be having any effect on the ship. It's almost as if the neutrinos are just passing right through it."
Okay, stupid, I know. Sorry.
Uhm, wouldn't this just be a simple incident of a journalist trying to transform scientific logic into human readable story?
You know, journalists don't really have to obey the laws of logic in the purest form possible, that's why they are called "journalists", and why they're not called "scientists"
--
Bizar technology?
Neutrinos don't ordinarily react with matter, but...obviously they have to interact on occasion to be measured at all. I wonder if there would be any way of significantly artificially enhancing the reaction rate?
Well, light is doing pretty well without mass.
If not now, when?
Well, yeah, the cool part is obvious.
The depressing part is that, at some point, it would be nice if we really, truly knew how all this shit worked so we could start doing things with it. A true understanding of the Fundamental Nature Of The Universe (tm) might bring a lot of our science-fiction dreams to life; at worst, it would let us know which dreams were possible and worth pursuing (FTL? Time travel? Telepathy? Etc.) and which ones weren't. As long as the FNOTU stays mysterious, we simply will have no idea.
The correlation between ignorance of statistics and using "correlation is not causation" as an argument is close to 1.
... "job security for particle physicists." Every time they answer a weird question, it raises a bunch of new, weirder questions.
I'm not sure if this is cool or depressing.
The correlation between ignorance of statistics and using "correlation is not causation" as an argument is close to 1.
If they have mass, then we must include that mass in all calculations, but for some reason they don't want to :-)
The current standard model does not predict the masses of neutrinos, but its equations are simpler if neutrinos have no mass.
That's like saying calculating the velocity of an object is easier to calcuate if we don't count friction!
Doh!
awhile back /. had an article on the Space (ie. Pioneer 10/11) not moving as fast and as far as expected when they were leaving the galaxy. Could the Neutrino's be the reason?
Doh!
I hadn't seen yesterday's article. I got the links from a friend of mine, who's a grad student on the project.
-Erf C.
-Erf C.
Cthulu always calls collect...
So in that sense, a neutrino has mass, in that it has energy. But this result is saying a neutrino has rest mass -- if you were to (somehow) stop the neutrino, so that it had no kinetic energy, it would still have mass, just like an electron.
-Erf C.
-Erf C.
Cthulu always calls collect...
Electrons are light enough that they travel at the speed of light at relatively low momenta. The experiment I'm working with will do most of its work at 30 MeV, and for all intents and purposes the electrons (which have a mass of 0.5 MeV) are moving at c (well, 0.99986*c). So basically they move at the speed of light in the vast majority of accellerators, with the exception of picture tubes. :)
-Erf C.
-Erf C.
Cthulu always calls collect...
These things are really really cool. You may be interested in the ALTA project -- they're putting cosmic ray detectors on the tops of high schools across Alberta, and letting the students there run them. The idea is to have a huge area over which to detect these things; they're pretty rare.
They're pretty mysterious, too. Nobody's really sure what sort of mechanism would throw off particles with this much energy. And it's not like we can just look up in the direction they came from, either -- the galaxy has a very slight magnetic field (but we don't know it that well), which bends the paths of charged particles (most cosmic rays), so the direction they hit the Earth from isn't the direction they really came from...
-Erf C.
-Erf C.
Cthulu always calls collect...
In physics, almost everything is an approximation. :)
-Erf C.
-Erf C.
Cthulu always calls collect...
The Sudbury Neutrino Observatory homepage has their own article about the results. The full paper that they submitted to Physical Review Letters is also avilable online.
-Erf C.
-Erf C.
Cthulu always calls collect...
Not only that, but the different neutrino flavours must have different masses in order to oscillate. The fact that they have mass at all is the most exciting bit, of course, but the fact that they're all different is pretty cool, too.
-Erf C.
-Erf C.
Cthulu always calls collect...
Okay, that was the odd way of going about it, but it makes sense to me. Just because something has a very tiny mass, that does not mean that it simply has no mass. Unless I can prove it one way or another, I will just base it on an assumption, and I would try to make it very clear that it is only an assumption until proven.
Just my two cents.
The underground observatory is also part of the supernova early warning systems that will alert the world to the next celestial storm generated by a supernova, or collapsing star. "If a collapsing star occurs in our galaxy instead of having one neutrino every two hours [register in the observatory], we'd have about 1,000 neutrinos in about two seconds," Dr. McDonald said, noting that such spectacular neutrino bursts occur in our galaxy about once a decade.
The above is from the National Post
Trevor.
Neutrinos, they are small. They have no charge, they have no mass. They do not interact at all. The Earth is just a silly ball to them through which they simply pass Like photons through a sheet of glass Or dustmaids down a drafty hall. They snub the most exquisite gas, Insult the stallion in his stall, Cold-shoulder steel and sounding brass And pass, like tall and painless guillotines, through you and me into the grass. At night they enter Nepal And pierce the lover and his lass from underneath the bed. You call it wonderful? I call it crass. - John Updike
ok then your [sic] infringing on my copyright! Could you as [sic] me next time before STEALING my comments for your own?
"On June 5, 1998, the Super-Kamiokande collaboration announced discovery of evidence for neutrino mass at the Neutrino '98 conference, held in Takayama, Japan."
ok then your [sic] infringing on my copyright! Could you as [sic] me next time before STEALING my comments for your own?
Neutrinos, they are small.
They have no charge, they have no mass.
They do not interact at all.
The Earth is just a silly ball
to them through which they simply pass
Like photons through a sheet of glass
Or dustmaids down a drafty hall.
They snub the most exquisite gas,
Insult the stallion in his stall,
Cold-shoulder steel and sounding brass
And pass, like tall and painless guillotines,
through you and me into the grass.
At night they enter Nepal
And pierce the lover and his lass
from underneath the bed.
You call it wonderful? I call it crass.
- John Updike
ok then your [sic] infringing on my copyright! Could you as [sic] me next time before STEALING my comments for your own?
ISTR that they were able to put a fairly solid cap on the rest mass of the neutrino based on some observations made during the big 1987 supernova. They detected a neutrino "pulse" (IIRC they only detected 7 neutrinos, but that is a lot for an event taking place that far away) just a few hours after the supernova was first apparent. That let them calculate a lower bound on the ratio of kinetic energy to rest mass for the neutrino and hence (since they can measure the kinetic energy) an upper bound on the rest mass.
There's no point in questioning authority if you aren't going to listen to the answers.
The book isSongs of Distant Earth, the first thing I thought of when I heard this on BBC Radio 4 (who needs /. when you have the Beeb). I'm quite relieved the events in the novel won't happen due to lack of neutrinos. There's a great throwaway line somewhere in the book, to the effect that after centuries of computer development, keyboards are still the best user interface.
Reader, you are much more likely to enjoy an unaltered transcription of Updike's Cosmic Gall . (Actually, I'm not sure it is unaltered, but it's at least as good as my memory, and it has the indentation. Depressingly, most versions I found on the web are wrongly formatted and have at least one obvious textual mistake.)
The evaluation of an action as 'practical' . . . depends on what it is that one wishes to practice.
Photons do *not* have mass, at least they do not have rest mass, which is what is meant here.
More technically, the rest mass of an object can be found through:
with E the energy and p the momentum. For photons, where E=pc, it's clear that m = 0. For a long time we thought the same thing applied to neutrinos, but apparently not...If you're jumping up and down saying, "But mass increases with velocity", you're using an outmoded lexicon. The idea of relativistic mass simply isn't useful, and can lead to a lot of misconceptions.
The Mongrel Dogs Who Teach
The centripetal force, Fc, must be provided by gravity alone, Fg. So
You might be thinking of Kepler's Third Law, which says that the square of the period is proportional to the cube of the distance. We can get there from here if we recall that where T is the period. Plugging that in above we'd have Ta-da!The Mongrel Dogs Who Teach
OK, more technically correct, tensors are like a generalization of vectors. They can be defined through the way they behave under rotations. And you're right: tensors are often represented through matrices.
In this forumulation, a scalar is a tensor of rank 0, a vector is a tensor of rank 1, and so on. Tensors are real bears to deal with. I went through an undergraduate program in Physics and never encountered them... they only really popped up in a class on General Relativity. Ugh.
The Mongrel Dogs Who Teach
I don't recall ever seeing anything that threw the fundamental basis of QM (OK, really, QED) into doubt. Indeed, quite the opposite -- things like the Aspect experiments, the stuff about Bell's inequality, and even the "teleportation" stuff seem to say, the Universe is actually as weird as QM makes it out to be.
The Mongrel Dogs Who Teach
"dark" matter: Matter that, for one reason or another, is not luminous. There is growing evidence that we cannot see all the matter in the Universe. The best evidence, IMHO, comes from studies of galaxy rotation, which show that galaxies are not rotating in a so-called "Keplerian" manner. A collection of particles orbiting a central mass should have a velocity that falls off (as 1/sqrt(r)) with distance. Saturn's rings do this, for example, which was how they were proven not to be solid.
It turns out that galaxies (which are rotating systems) do not obey this relation, as one might expect (since most of the luminous matter is contained near the center). This implies that there is something else "adding" mass as we travel out from the center of a galaxy. We can't see it, so it must be dark.
There are also cosmological arguments for dark matter. Most especially, there's a paramter (called Omega) which is the ratio of the Universe's density to "critical density". If Omega 1, the Universe will eventually collapse under the gravitational attraction of its elements. Observation of luminous matter indicates that Omega = 0.1. For a long time people had a bias that Omega should be exactly, leading to the claim that 90% of the matter must be "dark". Since that number agrees reasonably well with the one from galaxy rotations, people saw these as mutually supporting each other. (For the record, I find the cosmological evidence quite unconvincing.)
So, once you believe there is dark matter, you start to wonder what it's made of. In essence there are three classes of candidates:
- Regular, but cold, baryonic matter. This could be gas clouds, failed stars, burnt-out embers, etc. After all, things only glow if they're hot enough. Observed stars, etc. ("luminous baryonic matter") seem to have Omega_luminous about 0.01. Limits from Big Bang nucleosynthesis (the formation of elements in the creation of the Universe) seem to limit all "normal" matter to Omega_baryonic = 0.1.
- Neutrinos. We can estimate the flux of comsic neutrinos in the sky independently of their mass. Now that they've been shown to have some, we can estimate the total mass of neutrinos zipping around the Universe. According to the article, Omega_neutrinos is about 0.18.
- WIMPs: weakly-interacting massive particles. Since they're weakling interacting, they'd be hard to detect. These would be new particles, so far undiscovered, and they would involve that highest of objects, new physics. Candidates include axions, supersymmetric partners, and other more esoteric items.
No matter what the "dark matter" is, it will likely consist of anti-matter conjugates as well.The Mongrel Dogs Who Teach
You have to admit that what we call quantum mechanics today doesn't much resemble the quatum mechanics of the 1930's. But in the 1930's the perception was that physics had been "solved".
That's not even close to true. The QM you might study as an undergraduate physicist today is IDENTICAL to the QM derived in the 1930s. What HAS changed is not the theory, but the models the theory is applied to. And there were few physicists in the 1930s (nor today!) that would have claimed physics was "solved" as you put it; that sort of misunderstanding is usually based on popular accounts of cutting edge research, misunderstood and misinterpreted for nonscientists by other nonscientists. When trying to transfer knowledge to the nonscientist, things often have to be simplified, not only to explain it to a non-technical crowd, but also to simply fit it into the time allotted (it takes six or seven years of training and study to get to the point where you can even begin to understand the theories of modern physics at the level necessary to do research ... you can't transfer all that detailed knowledge to a non-scientist is a few minutes or hours, so something has to give).
As for how much of modern theory will be around in 50 years, just think of how much of modern theory existed 50 years ago: almost all of it! It's only the models, not the derivable theory, that has changed dramatically.
I did my undergraduate work at the University of Hawai'i. Ended up the sole student in a supervised senior survey in particle physics/cosmology with him, my last semester. Quite good, but required an extreme degree of self-direction. Given the rest of the university, it's amazing that UH has such a decent physics program.
Where were you doing SKAT work?
-- Still waiting for the Nike endorsement
The Yahoo (and to a lesser degree, the NYT) article was terribly dismissive of the results from the Super Kamiokande experiment, which had reduced the possibilities to two types of neutrino interaction - to-sterile neutrino oscillation, or to-tau/mu neutrinos... and made the sterile option terribly unlikely. This isn't an utterly new, wow-we-never-suspected sort of discovery - just a refinement of the data. More people (physicists) will find it credible, the degree of certainty has massively increased - but this isn't on scale with the confirmed discovery of a new particle. "We've solved a 30-year-old puzzle of the missing neutrinos of the Sun," the article quotes. Well, perhaps, but like the announcement from the Super-K (there was a huge, boastful quote from my dear old particle physics prof John Learned that was all over the papers), this is mostly hype. Still, got to keep yourself stimulated if you want to survive in academia...
-- Still waiting for the Nike endorsement
I didn't say American beer, I said good beer ;)
---
Hammer of Truth
And answer this... why are the majority of our beer sales shipped to bars in the states?
:)
They use it to water down the good beer.
---
Hammer of Truth
Since one of the other options was that the sun was in an unstable phase which would end with a nova or other major solar event in the next few thousand years. Clarke based one of his books on it, and it's also mentioned in McGervey's Quantum Mechanics.
I demand a million helicopters and a DOLLAR!
Now THIS is a .sig that i should be using *L* ... the United States, home of beer with alcohol content so low it has to be expressed in scientific notation ...
"dark matter" (i.e. anti-matter)
Dark matter and anti-matter are two different things.
[W]e can get infinitely close without ever reaching our destination
Your whole post is very well put. I would, however, humbly suggest that the word "asymptotically" is more apt than "infinitely".
the neutrinos arrived 8 days before the light. Probally because they could pass through the ultra dense shockwave of the supernova, while the light was trapped.
Spring is here. Don't believe me, look outside!
It is interesting to see if there is solid statistics behind this, or if it is just about making sure to hype it up to get more funding. (one shouldn't have to over-hype good research to get good grants, but those who sitting on the money don't care about science).
Employee of Inrupt, Project Release Manager and Community Manager for Solid
Forwarning: I'm working off of high school physics here.
In the NYT article, they mention that it takes a higher energy event to create the muon and tau neutrinos. To quote:
Presumably (remember, IANAP), that would mean that muon and tau neutrinos are of a higher energy than electron neutrinos. Yet this article says that the sun's electron neutrinos are changing into muon and tau neutrinos. This would mean that they are heading to a higher energy state, thus they are gaining energy in the depths of space!<Homer>In this house we obey the laws of THEMRODYNAMICS!</Homer>
One of the biggest astronomical mysteries was why the sun was not producing anywhere near the predicted amount of electron neutrinos. This experiment proves that it is in fact producing them, but that 60% of them transform into other neutrinos before reaching the earth.
Furthermore, it is this transformation that proves that they have mass.
From the article:
But on Monday, representatives of the Sudbury Neutrino Observatory in Canada announced that neutrinos made by nuclear reactions in the sun's core change from one type to another during their 93-million-mile journey to Earth. And only particles with mass can change form.
--
Garett
Why is American beer like sex in a canoe? They're both fucking close to water.
sulli
RTFJ.
Jeez, can't Slashdot get the categories right? Clearly this should be in the Sun category.
sulli
RTFJ.
Photons DO NOT have mass!
Numbers 31:17,18 Now kill all the boys. And kill every woman who has slept with a man,but save for yourselves every virg
As for your complaints about the +5, I agree. The mod system on Slashdot is far from balanced, and always favors the newest posts over later ones. It's worked against me, IMO, far more often then it's worked to my advantage.
Do any other already-known particles get that close to c without being at c?
You have *perfectly* described science, my anonymous friend.
The big problem then is that if you choose to ignore science and it's many approximations, you lose out on the wonderful things we get out of it...
Like cars, watches, computers, TVs, radios, plastic bottles, aluminum alloy wheels, titanium golf clubs, etc.
With each refinement of science we get ever more unexpected observations, and with each new observation we get new opportunities in which to create new and unexpected devices.
As we refine the neutrino and the elementary particles we can eventually devise gadgets that rely on the characteristics that these neutrinos have.
Seriously, what would you have us do? Decide "Physics, chemistry, and science is done. No more research, everything is finished."
Science is the process by which we try to deduce the pattern, the weave, the weft, of creation, and to satisfy your set of beliefs, the underlying structure as given to us by God. Without science we would have no understanding. Science is constrained to be an approximation, to use heretical thoughts, because the Universe and God is unknowable; we can get infinitely close without ever reaching our destination.
Geek dating!
GPL Deconstructed
[100% ISO 646 Compliant]
SVM, ERGO MONSTRO.
I love to ask this, if light has no mass then why dose gravity effect it?
It's all a matter of the distinction between rest mass and effective mass. Rest mass is mass that a quanton has when it has zero energy. Effective mass is the mass that it "effectively" has when it is in an excited state.
Because the energy imparted to a quanton increases its momentum, this can be accounted for in equations by increasing its effective mass. Both effective and rest mass are "mass", but there is a subtle difference between them.
No. p = mv isn't relativistically correct. You just get E = pc.
Sorry about that, perhaps I was a little bit hasty. The development of the deBroglie relationship actually goes more like this:
E = hc/lambda. Also, E^2 = p^2v^2 + m_0^2c^4.
We can equate the two of these, because they are both valid for light. Also, for light, v = c, and m_0 = zero. Thus
hc/lambda = pc
h/lambda = p.
That was just the derivation of the deBroglie relationship, nothing more.
It may look like I'm doing nothing, but I'm actively waiting for my problems to go away.
--Scott Adams
This is a tricky question.
It is energy and momentum that are related, not energy and mass. There is a fine line between the two. For instance, when calculating reactions, you must conserve energy (a scalar quantity) and momentum (a vector quantity), not energy and mass.
Some confusion arises from people quoting the equation
E=mc^2
but this is an abridged version, and many people leave out some critical subscripts. In actual fact, it should be
E^2 = (p^2)(c^2) + (m_0^2)(c^4)
where p is the momentum of the quanton, and m_0 is its REST mass. Thus, for photons with no rest mass, take the square root of both sides and substitute p = mv, where v=c, the speed of light, and
E = mc^2
It is also from this simplified equation that we can substitute the energy of a wave (E = hc/lambda) and get the deBroglie relationship
h/lambda = mc = p
Now, back to the subject at hand, both of you are kind of correct. Light has no rest mass, but light with any amount of energy does have momentum (which can be interpreted as it having mass, but only loosely). If light bends because it is travelling in a straight line through curved space-time, it is only travelling in that straight line because it has momentum, and that momentum is being conserved.
It may look like I'm doing nothing, but I'm actively waiting for my problems to go away.
--Scott Adams
I've been reading Slashdot for month's, but I've never posted. Well, today is important enough, and so to you, gentle reader, I say:
I've been to the SNO! Nyah nyah nyah!! There are no public tours, but I got it!
Heck, I even got a t-shirt (really!)
But, to be serious, the whole project is really quite impressive. It's 6800 feet down in the Creighton Mine, which is an active Nickel mine that extends to about 7200 feet (it's something like the 2nd deepest in the world). Being surrounded by so much dense rock means that very little radiation other than Neutrinos reaches the Heavy Water (s/Hydrogen/Deuterium/) tank.
The ambiant air temperature (outside the air-condition and pressure-sealed lab area) is somewhere aroung 25-30 degrees C (it gets hotter the deeper you dig).
The Heavy Water (1000 tons) is on loan from various Canadian nuclear power plants. I believe that Canada is the world's biggest producer of Heavy Water (Fact: ~.05% of the water you drink is Heavy!)
If you're ever in Sudbury, visit Science North, which has some great displays about SNO.
My religion forbids the use of sigs.
For more info, see The Supernovae, Supernova Remnants and Young-Earth Creationism FAQ which covers this in some detail.
Disclaimer: I'm the author of said article
First creationists, and now all the other crackpots with their pet theories are climbing out from underneath whatever stone they're usually hiding beneath.
The Sun is powered by thermonuclear reactions. The evidence is overwhelming.
If you don't like this fact, tough. Get over it.
You are entitled to your own opinions, but not to your own facts.
Nutri-Nose! Yes! Nutri-Nose makes noses grow B-I-G! Yes, You too can have a schnoz to make Pinocchio envious! You too can have a beak the size of Baron Munchausen's! Have the biggest snot locker on the block!
Obligatory disclaimer: "These statements have not been evaluated by the Food and Drug Administration. WARNING: Contains radioactive material."
Trying to find the mass of neutrinos is like trying to weigh a soda can on a truck scale. If the soda can was full of crap, and the scale was calibrated just right, it just might register. That's the difference between an electron and it's neutrino: A neutrino is just an empty can. An electron is a can filled with a charge. But the can still has mass, it is just very hard to weigh with truck scales.
- The electron microscope
- The Canadarm
- instant potato flakes (and we appologise)
- The telephone, fer crying out loud.
- Pablum
- The pacemaker
- IMAX
- Insulin!
- Java
Their are more.They use heavy water (D2O) instead of H20.
My dingo ate your honor student.
Light has no mass. But is has momentum and energy. E=mc^2 doesn't work for light for obvious reasons. If I gave you a photon of some arbitrary energy value, you can't determine its mass with that equation. Neutrinos on the other hand DO have mass (not thanks to the Canadians but the Japanesse 1996 IIRC). Sure they might get most of their mass from relativistic effects, but so what, they have mass. Don't get me wrong, I don't think the experiment above is wasting its time. Why something on the order of 30% of our universe is neutrinos, so I would expect many significant contributions from all of the neutrino experiments in operation. But proving the neutrino has mass isn't a contribution of this experiment. It's probably just the obligitory paper, following up with a "me too". Maybe this would be "News for Nerds" is the title was "Another experiment...." Maybe I should get a hobby.
--Jimmy has fancy plans; and pants to match.
Light does not have mass. Light does respond to the curvature of spacetime, as does everything. But this in no way even hints that light has mass. Which is why I'm pretty sure this is a troll. I could almost buy into that someone might mistake radiation pressure and the fact light has momentum as proof light has mass, but not this.
However, should my estimation be wrong, I have a few suggestions.
Relativity by Albert Einstein, Wings books ISBN 0-517-029618 (cloth) -025302 (paper)
Modern Physics by Tipler, Worth Publishers ISBN 0-87901-088-6
Relativity is actually pretty light on math, short and easy to read. I'd say one could read it easily in an evening. Tipler's on the other hand is my old text book, it's solid in that respect, but not particularly enthralling.
The gravitational lensing which you describe is mearly the result of light following a straight line on spacetime (which is curved). As such it's totally independant of whether or not light has mass.
--Jimmy has fancy plans; and pants to match.
If neutrinos have mass, does this mean that anti-neutrinos have pagan rituals? hmmm...
I guess the Italian sounding name should have clued me in.
good response... thanks, I appreciate that...
I understood the article, and I'm a filmmaker. If this stuff needs to be made so patronizingly simple, I suppose that "nerd" doesn't imply much beyond someone who likes star trek (but doesn't understand cosmology) and who plays video games (but can't necessarily code them). What is this, USA today?
I guess I just think it's odd that someone can get a plus 5 for regurgitating completely obvious information, with no take on it at all.
Now maybe if you'd thrown in some colored bar graphs with neutrino icons, you'd be on your way toward a serious journalistic career in this country...
An empirical proof has only traditionally been accepted as valid if it can be replicated. Scientists are a sceptical bunch. They don't want to be told what's so, they want to be told how to prove to themselves that it's so. Otherwise they're just taking it on faith.
And this neat high/low energy stuff requires such specialised equipment that it's largely a case of doing the experiment, publishing the results and saying "Believe it or not..."
Are we coming full circle on the whole religion/science thing? I mean, how many of us have personally and quantifiably verified that E=mc^2, let alone the tricky stuff? ;)
If you were blocking sigs, you wouldn't have to read this.
I wonder (in a casual college physics dropout kind of way) where the line is between zero rest mass (v == c) and very very very small rest mass. (v
It seems vaguely unsettling to have a whole slew of energetic particles spewing out from sub atomic interactions, with a continuum of rest mass right down to this point and no lower, below which you get m==0, v==c photons.
I guess I'm just not comfortable with the idea of absolutes. Can I trade this universe in for a fuzzier one please? ;)
If you were blocking sigs, you wouldn't have to read this.
"Hardly used" will not fetch you a better price for your brain.
Also, this revelation 'debunked' nothing. There was no consensus before as to whether or not neutrinos had mass: now there is strong evidence that there is.
I'm sorry if I sound a little huffy, but this post sounds like a plea for deliberate ignorance, i.e., "We'll never really know, science is just another story, so let's just say the earth is flat and was created in six days, mmmkay?"
"Hardly used" will not fetch you a better price for your brain.
I didn't know they were catholic.
I guess it would be Sirius' companion star that would supernova. I'm not sure how much damage it would do to us, but we could get a nice tan from it.
-bq
Maybe neutrinos like to fool around with scientists and their stuff. Quantum joking :D
Now I have mass, now I don't! Catch me while you can!
--- Hajotkaa siihen, kapitalistit!
Gravity doesn't *effect* it - gravity *affects* it!
What is the mass of blue? What is the mass of anger? What is the mass of North? All of these massless things exist, do they not? Duhhhhhh
The article is a very nice introduction for us non-physicists, but nothing it relates is by any means definitive. As this latest discovery proves, our understanding of the universe is constantly being updated, and older theories are being refined or replaced.
:-)
So, I don't think we yet have any real knowledge of whether the Universe is curved or flat, or whether it will expand infinitely or begin to contract inwards at some point. The truth is, there are still so many other pieces of the puzzle that haven't been clearly and conclusively placed yet, that we couldn't possibly see what the whole picture is going to be, or even whether there is a conclusive "whole picture" at all--if quantum physics has taught us anything, it's that we can't be certain what surprises lie ahead.
I mean, so much has changed in terms of what theories are most accepted and which are minority theories, just in the five years since I studied physics in college. And minority theories could be correct--just because 70% or even 95% of physicists believe something, doesn't make it so. Maybe the other 5% are the more brilliant ones, you never know.
I enjoy reading about physics and cosmology immensely--but we don't know much yet. There's still so much to confirm, discover, and rethink. Maybe that's why I like it so much.
Chasing Amy
(We all chase Amy...)
Chasing Amy
(We all chase Amy...)
"The more corrupt the state, the more numerous the laws"-Tacitus
neutrinos made by nuclear reactions in the sun's core change from one type to another during their 93-million-mile journey to Earth. And only particles with mass can change form.
ok fair enough... but then it goes on to say...
- The standard model, the reigning theory in particle physics, does not allow particles that change their flavor to have mass. So that theory will have to be patched up - though not discarded - to accommodate the new observations.
what is the difference between changing "form" and changing "flavor"?
why is one theory "patched up" and the other accepted as true? maybe just bad writing (or bad understanding) but it seems to put faults in validity of an experiment if one has multiple opposite theories lying around to pick from and "prove" your chosen point.
For some reason, Netscape is crashing when I hit reply on this. So lynx it is and forgive any malfunctions.
On the question of the original view of the mass of neutrinos as taught in high school science class, I think it bears pointing out, once again, the exact nature of the energy/mass/velocity relationship. Quoting myself, e=mc^2 is " e in one sense is the energy an object has, and m is the mass resulting. in another sense, e is the energy needed to accelerate m, the given mass." Both sides of the equation represent the same things, only different facets. Thus we can extrapolate from this that neutrinos have mass, inasmuch as they have energy while in motion, since energy is directly proportional to mass. In the question of whether they themselves have mass, at a resting state, no definitive answer has been discovered. This new experiment would indicate yes, but I suggest we all remain skeptical - this is a simple experiment that could have been done years ago, which makes me wonder why it is being done just now.
think for yourself, you won't like the results if others do it for you.
Light does have mass - light is simply a collection of packets called photons. Experimentation and observation has shown that light beams from distant stars are wrapped around gravity wells. One of the first verifications of Einstein's General Relativity was a solar eclipse being used to measure the locations of stars in the sky, their light coming from behind/around the sun, and it was seen that their locations were changed because of the gravity bending the stream of light.
think for yourself, you won't like the results if others do it for you.
No, it was not a troll. I am serious, I remember Hawking's A Brief History of Time claiming that light does have mass. However, I could be badly mistaken, I might have misunderstood, the mass spoken of might have been related to motion the way most neutrino mass is. If so, I stand corrected. I'll check my sources.
think for yourself, you won't like the results if others do it for you.
Neutrin-O's! For the real health conscious!
Depends on the E given off
Well that is my point - we will never KNOW. We'll have theories that haven't been disproven yet. Although I would not argue that we shouldn't pursue knowledge - I'd just argue that we keep it in perspective.
Debunk was probably a poor choice of words. But there have numerous times along the way when science has stated theory as fact only to later reverse. One obvious example that comes to mind is Dirac's equation which "solved" physics. Protons, electrons and nuetrons were the three "fundamental" bulding blocks of everything. You have to admit that what we call quantum mechanics today doesn't much resemble the quatum mechanics of the 1930's. But in the 1930's the perception was that physics had been "solved". I guess my point is more of a thought - I wonder how much of the modern day theory will be unchanged 50 years from now?
Does anyone else get the impression that we keep "proving" our physical observations which are incredibly limited by current technology only to revise as our technology gets better? I wonder how long it will be before we debunk all quantum mechanics?
She: I'm so fat! I've gained a ton!
He: No, Honey. It's just all those neutrinos that collided with you...
Fascism starts when the efficiency of the government becomes more important than the rights of the people.
They use it to water down the good beer. :)
:)
Wha...? Ok I think I've had enough Canadian beer for today.. hehe How does one water down american beer with canadian beer?
Mouse, Mice. Goose, Geese. Moose... Moose?
All hail the lord god Python almighty... :)
Mouse, Mice. Goose, Geese. Moose... Moose?
If you're from the states, send me up a 12 of your Budweiser "Strong". I'll send you a 12 of what we call "strong". We'll see who gets tanked first :) And after I'm done, I'll drink the other 11 you couldn't finish :)
And answer this... why are the majority of our beer sales shipped to bars in the states?
Mouse, Mice. Goose, Geese. Moose... Moose?