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Are Quarks Real?

Started by Solitary, July 05, 2013, 09:00:21 AM

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Solitary

:evil:
There is nothing more frightful than ignorance in action.

Jason78

Quote from: "Solitary"A wave function has never been observed , and neither has a quantum field, or even a classical electromagnetic field.

A sheet of white paper, a bar magnet and iron filings.  There's your classical electromagnetic field!
Winner of WitchSabrinas Best Advice Award 2012


We can easily forgive a child who is afraid of the dark; the real
tragedy of life is when men are afraid of the light. -Plato

Solitary

#2
:evil:
There is nothing more frightful than ignorance in action.

Youssuf Ramadan

Quote from: "Solitary"A sheet of paper is not an electromagnetic field or quantum field. You would be seeing the metal filings forming a pattern that represents the field not the field itself.

Nobody's ever seen gravity either, but... um... yeah...  :-k

GurrenLagann

Sounds more like a philosophy of science question than an science one.
Which means that to me the offer of certainty, the offer of complete security, the offer of an impermeable faith that can\'t give way, is the offer of something not worth having.
[...]
Take the risk of thinking for yourself. Much more happiness, truth, beauty & wisdom, will come to you that way.
-Christopher Hitchens

the_antithesis


Jason78

Quote from: "Solitary"A sheet of paper is not an electromagnetic field or quantum field.

Are you yanking my chain?

Quote from: "Solitary"You would be seeing the metal filings forming a pattern that represents the field not the field itself.

Seriously?  

I don't suppose you saw the point I was making whistle past?   I can't show you the actual field.  You're not really capable of sensing it.  

Quote from: "Solitary"The electromagnetic field may be thought of in a  'coarse' way. Experiments reveal that in some circumstances electromagnetic energy transfer is better described as being carried in the form of packets called quanta (in this case, photons) with a fixed frequency. Photons enable us to see, but we can observe them directly. Solitary

Yeah, you can't see individual photons.  That's why we have photomultiplier tubes.  They can directly interact with a photon.      
You can't see individual electrons.  But you can watch them arc between two wires.  You can catch them in a penning trap.  You can send them whizzing around 25km of underground tunnels and slam them into a target.  

You can't see individual yeast either, but I can throw a handful of it at you.
Winner of WitchSabrinas Best Advice Award 2012


We can easily forgive a child who is afraid of the dark; the real
tragedy of life is when men are afraid of the light. -Plato

Solitary

Quote from: "Jason78"
Quote from: "Solitary"A sheet of paper is not an electromagnetic field or quantum field.

Are you yanking my chain?

Quote from: "Solitary"You would be seeing the metal filings forming a pattern that represents the field not the field itself.

Seriously?  

I don't suppose you saw the point I was making whistle past?   I can't show you the actual field.  You're not really capable of sensing it.  

Quote from: "Solitary"The electromagnetic field may be thought of in a  'coarse' way. Experiments reveal that in some circumstances electromagnetic energy transfer is better described as being carried in the form of packets called quanta (in this case, photons) with a fixed frequency. Photons enable us to see, but we can observe them directly. Solitary

Yeah, you can't see individual photons.  That's why we have photomultiplier tubes.  They can directly interact with a photon.      
You can't see individual electrons.  But you can watch them arc between two wires.  You can catch them in a penning trap.  You can send them whizzing around 25km of underground tunnels and slam them into a target.  

You can't see individual yeast either, but I can throw a handful of it at you.


QuoteA sheet of white paper, a bar magnet and iron filings. There's your classical electromagnetic field!

You really believe that, fine with me. Detecting an electromagnet "field" or quantum "field" is not the same as seeing either of them. I can have a sensor in the road that can detect a car I can't see too. I'm not yanking your chain, but I'm starting wonder whether you are mine.

QuoteI don't suppose you saw the point I was making whistle past?

No I sure didn't! What was your point?

Victor J. Stenger an adjunct professor of philosophy and emeritus professor of "physics" and he agrees with me, as well as a friend that is an Engineering physicist. Show me how a sheet of paper is a classical electromagnetic field. I didn't say a field doesn't exist, I said they can't be seen. Do I need to add: with the human eye with no help? Solitary
There is nothing more frightful than ignorance in action.

Colanth

Quote from: "Solitary"A wave function has never been observed , and neither has a quantum field, or even a classical electromagnetic field.
Functions and fields don't reflect light, so they can't be 'seen'.  Are your thoughts real?  They can't be seen either.  Did yesterday actually happen?  You can't 'see' it.

Your statement is incompetent (meaning that it's not the kind of statement that can be responded to).  Functions and fields can be 'observed' - which doesn't necessarily require vision.  The pattern of iron filings on a piece of paper with a magnet under it allows us to observe the magnetic field.  (Remember, you don't actually 'see' anything.  The light that reflects from it impinges on your retinas, and your brain interprets the resulting change in the rhodopsin in your retinas as indicative of what the object looks like.  So using your own argument, nothing exists, since vision is merely the brain's interpretation of a second-hand analogue of reality, it's not a direct 'seeing'.)

Quarks have been observed in much the same way as you 'observe' the monitor you're reading this on - sort of indirectly.  The question of whether they actually exist is no more a question than the one of whether your monitor exists.  (Touching the monitor doesn't change anything - the 'feeling' of the monitor is merely your brain's interpretation of chemical changes in the nerve endings in your fingers.)
Afflicting the comfortable for 70 years.
Science builds skyscrapers, faith flies planes into them.

LikelyToBreak

I don't understand quantum mechanics or fields.  And if I remember right, neither did Richard Feynman.

At any rate, is there a point with this?  Maybe I am just too ignorant to see one, but it seems like all that is going on is an argument about how many angels can sit on the head of a pin.  Until there is more data, which is being collected almost everyday, we can't really tell what is going on in quantum fields.  IMHO.

Hakurei Reimu

Quote from: "Solitary"The question of quarks being real is still an open question.
It's pretty much settled at this point that they do really exist. Not only do our theories work well only when we include them, but when we fire high-energy electrons at hadrons, you see three points of deflection in baryons, and two in mesons, exactly as our theories say they should.

Remember that the fact that we don't find quarks in isolation doesn't mean that they cannot be detected by other means.

Quote from: "Solitary"Applying metaphysics to quantum mechanics, the wave function, a type of quantum field is real and so its simultaneous collapse throughout the universe violates relativity that has been tested to be true many times.
Except that these collapses don't transfer information, (the fact that relativity was 'violated' only appears after you compare notes) so it's all good.

Quote from: "Solitary"The wave function is simply a human-invented mathematical object that can do anything its inventors want it to, so long as any calculations made agree with data.
You've just described the function of every piece of mathematics in science.

Quote from: "Solitary"A wave function has never been observed , and neither has a quantum field, or even a classical electromagnetic field. All detectors ever register are localized hits that look very much like particles.
Yep. And you've never seen the inside of a brick, either. Even when you break one, all you see is an additional surface created when you broke it. Yet we still think that bricks have insides.
Warning: Don't Tease The Miko!
(she bites!)
Spinny Miko Avatar shamelessly ripped off from Iosys' Neko Miko Reimu

Solitary

QuoteYour statement is incompetent

Really?

By exploring magnets, students are indirectly introduced to the idea that there are forces that occur on earth which cannot be seen. This idea can then be developed into an understanding that objects, such as the earth or electrically charged objects, can pull on other objects. It is important that students get a sense of electric and magnetic force fields (as well as of gravity) and of some simple relations between magnetic and electric currents (Benchmarks for Science Literacy, p. 93.) In grades 3-5, students should have had opportunities to observe and explore the lines of force, the attraction and the repelling forces that all magnets exhibit in activities such as those found in Magnets

In this lesson, students will see evidence of the magnetic field of a small magnet.


Planning Ahead
Gather the materials for both parts of the activity and perform the experiments yourself before you do them with the students. If you are using loose filings, clean them up very carefully. To pick up the filings easily, slip your magnet inside a plastic bag. Run it over the loose filings and it will pick them up easily. To remove them from the magnet, simply remove the bag. Store iron filings separately from the magnets so they won't become demagnetized.

Motivation
Begin by asking students to discuss their experiences with magnets. More than likely, students have conducted simple activities with magnets in earlier grades. Ask students to describe what magnets are and how they work. This discussion will help you assess students' naïve explanations of magnetism, which will be helpful as you guide them to more scientific explanations.

Development
The first part of this lesson is a hands-on exploration of magnetic fields using the Exploring Magnetic Fields: Activity 1 student sheet.

Allow students to work in pairs or small groups to carry out the activity. Each student, however, should fill out the student sheet. When students have finished, ask students to describe what happened. Ask one or more students to share their drawings of the patterns made by the iron fillings with the class.

Then discuss these questions:
Were the patterns and shapes formed by the iron filings the same no matter how many times you did the experiment?

What do you think caused this pattern?
After students have shared their ideas, explain that the pattern they saw was the outline of the magnetic field around the magnet. Around every magnet there is an invisible field called a magnetic field. This field is what attracts items such as paper clips and nails to the magnet. Although the magnetic field is invisible, the iron filings indicate where it is because they line up with the field.

Have students continue with their exploration of magnetic fields, using Exploring Magnetic Fields: Activity 2 student sheet.

Please note that students will repeat part of the first activity so that they can compare the magnetic field created by one bar magnet to that of other combinations and types of magnets.
After students have completed the activity, have them discuss their findings by reviewing the questions on the Student Sheet and sharing their drawings of what they observed.
To reinforce the concepts in the lesson, ask the following questions:

Could you see the magnetic field? (No, the magnetic field is invisible. What was observed was the pattern made by the field.)

Were the field lines the same for each type of magnet? (The field lines you see will be different when you use different magnets.)

Where does the field seem to be the strongest? (Magnets have two poles; the field lines spread out from the north pole and circle back around to the south pole. Iron filings line up along the lines of magnetic force. The field is strongest at the poles; this is where the iron filings tend to be the most concentrated.)

How was this activity similar to that in Part 1? How was it different? What more did you learn?
Although the thin layer of iron filings we use in this activity only shows the magnetic field in two dimensions, it really is three-dimensional. The lines of force in the field extend upward and downward as well as from side to side. In fact, you can see some of these lines near the pole of the magnet where some of the filings seem to stand up straight in the air. If we had a way to see it, these lines would curve upward and then back down toward the other pole of the magnet, just like those we can see in the filings. The earth's magnetic field looks very much the same, although it is much larger.

Assessment
After students have thoroughly discussed the activities in the student sheet, refer students to Magnetic Fields. Instruct students to read this article and use what they have read to explain what happened in the activity. This will help them to refine their ideas about magnetism and to express their explanations in a more scientific way.

Extensions
Magnetic Fields: History discusses the history of magnetism and includes directions for conducting the experiment done by Hans Christian Oersted in which he discovered that an electrical current creates a magnetic field.

Magnets Part 1 and Magnets Part 2, from the Fermi Lab's High Energy Physics Made Painless Website, further extends the ideas in this lesson and discusses the use of magnets in particle accelerators.

Magnetic Shielding, from the Exploratorium, is an activity that extends the ideas in this lesson.


So, this is for grades 3-5, and the Reponses to my post show that a lot of you never understood what you were doing in science classes. Anyone still want to say they can see an electromagnetic field and that my statements are incompetent?  :popcorn:   :roll: Solitary
There is nothing more frightful than ignorance in action.

Plu

Yeah, gladly. If you believe that magnetism is real, then the same logic works to prove that quarks are real. If you don't believe that magnetism is real, I don't really know what more to say.

You cannot claim "magnetism is real even though we cannot see it but quarks are not real because we cannot see them" without fundamentally breaking down your own argument. Either it's irrelevant to a thing's existance whether or not we can "see" it (which gives us modern science) or only things we can see are real (which would bring us back to even before primitive religion, as even primitive human beings understood that things you couldn't see were still there)

We have observed quarks interacting with the real world. We can make predictions based on their existance, and they come true. They are "real" for any scientific definition of the word "real". If their observance breaks any other law of physics (which, according to Hakurei they don't,  and she usually knows what she's talking about) then this simply points out that the other law is wrong. Because regardless of whether "quarks" are real or their theory is sound, we have still made an observation that breaks a physical law.

Solitary

Quote from: "Plu"Yeah, gladly. If you believe that magnetism is real, then the same logic works to prove that quarks are real. If you don't believe that magnetism is real, I don't really know what more to say.

You cannot claim "magnetism is real even though we cannot see it but quarks are not real because we cannot see them" without fundamentally breaking down your own argument. Either it's irrelevant to a thing's existance whether or not we can "see" it (which gives us modern science) or only things we can see are real (which would bring us back to even before primitive religion, as even primitive human beings understood that things you couldn't see were still there)

We have observed quarks interacting with the real world. We can make predictions based on their existance, and they come true. They are "real" for any scientific definition of the word "real". If their observance breaks any other law of physics (which, according to Hakurei they don't,  and she usually knows what she's talking about) then this simply points out that the other law is wrong. Because regardless of whether "quarks" are real or their theory is sound, we have still made an observation that breaks a physical law.

"Gladly?"  Jesus H. Christ!! Show me where I said quarks aren't real, or magnetism isn't real. I said one cannot SEE electromagnetic fields or quarks. You can observe the interactions, but you can't actually see them. And I never said a word about any theory being wrong either. Do all you critics just read the heading and not read the whole paragraph?  Like you said: "They are real for any scientific definition of the word real." They still can't be seen.  

Quarks are the current "best fit" theory for what we think we know about the neutrons, protons, and other mesons. They are just as "real" as point-like particles can be.

Might be something inside the quarks, but right now, the energies required to figure them out are beyond today's technology.

According to Super String Thoery, quarks will be found to be made of tiny vibrational modes of energy, folds in 11 dimensional space-time. But whether this fits the data better remains to be seen.

How do scientists know the existence of Quarks in protons and neutrons? And how do they know they are fundamental particles?

A:

,That's a tough question to answer since no one has actually seen a real isolated quark You have to rely on indirect evidence. Fortunately there is plenty of that.

Just as Ernest Rutherford determined that the nucleus of the atom was a small compact object by observing alpha particles back-scattering from it, today's physicists perform similar experiments by scattering high energy electrons off of protons.

The resulting angular distribution of these scattered electrons can be explained only if there are tiny constituents inside the proton (as well as neutron). Additional evidence comes from the observed patterns of mesons and baryons that are produced at high energy accelerators. These patterns can be neatly explained by assuming a few types of fundamental quarks that combine with each other to form the observed particles.

As to whether the quarks are made of still smaller sub-quark things, we don't know for sure but as of now there is no evidence for that.

How can one be so confident of the quark model when no one has ever seen an isolated quark? There are good reasons for the lack of direct observation. Apparently the color force does not drop off with distance like the other observed forces. It is postutated that it may actually increase with distance at the rate of about 1 GeV per fermi.

 A free quark is not observed because by the time the separation is on an observable scale, the energy is far above the pair production energy for quark-antiquark pairs. For the U and D quarks the masses are 10s of MeV so pair production would occur for distances much less than a fermi. You would expect a lot of mesons (quark-antiquark pairs) in very high energy collision experiments and that is what is observed.

Basically, you can't see an isolated quark because the color force does not let them go, and the energy required to separate them produces quark-antiquark pairs long before they are far enough apart to observe separately.

One kind of visualization of quark confinement is called the "bag model". One visualizes the quarks as contained in an elastic bag which allows the quarks to move freely around, as long as you don't try to pull them further apart. But if you try to pull a quark out, the bag stretches and resists.

Another way of looking at quark confinement is expressed by Rohlf. "When we try to pull a quark out of a proton, for example by striking the quark with another energetic particle, the quark experiences a potential energy barrier from the strong interaction that increases with distance." As the example of alpha decay demonstrates, having a barrier higher than the particle energy does not prevent the escape of the particle - quantum mechanical tunneling gives a finite probability for a 6 MeV alpha particle to get through a 30 MeV high energy barrier.

But the energy barrier for the alpha particle is thin enough for tunneling to be effective. In the case of the barrier facing the quark, the energy barrier does not drop off with distance, but in fact increases.

In 1977, an experimental group at Fermilab led by Leon Lederman discovered a new resonance at 9.4 GeV/c^2 which was interpreted as a bottom-antibottom quark pair and called the Upsilon meson. From this experiment, the mass of the bottom quark is implied to be about 5 GeV/c^2. The reaction being studied was

where N was a copper or platinum nucleus. The spectrometer had a muon-pair mass resolution of about 2%, which allowed them to measure an excess of events at 9.4 GeV/c^2. This resonance has been subsequently studied at other accelerators with a detailed investigation of the bound states of the bottom-antibottom meson.
Next!  :roll:  Solitary
There is nothing more frightful than ignorance in action.

missingnocchi

Quote from: "the_antithesis"[ Image ]

Ferengi?

This thread:
Solitary: Are quarks real? No one has ever seen one!
Everyone: Yes, because we have observed them through indirect methods.
Solitary: FOOLS! I tricked you! You thought I was saying quarks aren't real, but they are! We can observe them through INDIRECT methods!
What's a "Leppo?"