Lots of smart folks right here, but I was wondering if there are any good Physics forums where informed laymen like myself can ask questions but not be dismissed because I’m not an actual physicist?
Short of that, does anybody here know why everything in fundamental physics seems to be particle based? For example, I’m watching a show on the Higgs-Boson particle. Evidently the LHC can create energies that will result in being able to observe the H-B. But why do they think it’s a particle in the first place? Or is “particle” just a handy term they use and not really an actual particle in the more common sense.
Thanks, these both look great.
Short of that, does anybody here know why everything in fundamental physics seems to be particle based? For example, I'm watching a show on the Higgs-Boson particle. Evidently the LHC can create energies that will result in being able to observe the H-B. But why do they think it's a particle in the first place? Or is "particle" just a handy term they use and not really an actual particle in the more common sense.Intriguing question. Apparently, quantum "particle" is a misnomer from classical physics. http://en.wikipedia.org/wiki/Particle_physics
To be specific, the term particle is a misnomer from classical physics because the dynamics of particle physics are governed by quantum mechanics. As such, they exhibit wave-particle duality, displaying particle-like behavior under certain experimental conditions and wave-like behavior in others.There are no defined particles per se (as there are in the macro realm) in the micro quantum realm. Apparently, there are only fields (whatever they are). http://arxiv.org/ftp/arxiv/papers/1204/1204.4616.pdf
Particles are epiphenomena arising from fields. Thus the Schroedinger field is a space-filling physical field whose value at any spatial point is the probability amplitude for an interaction to occur at that point. The field for an electron is the electron...bold added by me. So, is it fields and/or particles? From the introduction of the above cited paper:
But fields-versus-particles is still alive and kicking, as you can see by noting that "quantum field theory" (QFT) and "particle physics" are interchangeable names for the same discipline!Also:
Physicists are schizophrenic about fields and particlesAnd what are fields? Don't ask. Fields are supposed to extend to infinity.... Ignorance is bliss. :cheese:
Short of that, does anybody here know why everything in fundamental physics seems to be particle based? For example, I'm watching a show on the Higgs-Boson particle. Evidently the LHC can create energies that will result in being able to observe the H-B. But why do they think it's a particle in the first place? Or is "particle" just a handy term they use and not really an actual particle in the more common sense.It just seems so, because it is the easiest way of speaking. Matter of fact is that the Higgs field was needed to explain why particles have mass. As a consequence of the existence of the Higgs field, there also should exist a Higgs particle, i.e. an local interaction of the Higgs field with other fields. Because that is what a particle is: the interaction between quantum fields. Quantum fields develop deterministically in time when left on their own, but when they interact this interaction is local. This local interaction gives the 'particle-impression'. Where and when exactly the interaction takes place is a statistical process, it cannot be predicted exactly. Measurements are interactions per definition, so we measure 'particles', even that they were no particles until they interacted. Maybe they should have found a new word for quantum objects, to stop all confusions, something like 'potactons' (the 'potential to act')... For the best lay explanation about the Higgs 'particle' I know until now, see MinutePhysics ]on Youtube.
Quantum fields are not real unlike the electromagnetic (EM) field which is a physical field produced by electrically charged objects which can be detected, observed and measured.
What is a quantum field?
No one has ever observed a quantum field. Quantum fields are purely mathematical constructs within quantum field theory.OTOH, quantum "particles" are real. They can be detected, observed and measured:
Every quantum field has associated with it a particle that is called the "quantum of the field." The photon is the quantum of the electromagnetic field. The electron is the quantum of the Dirac field. The Higgs boson is the quantum of the Higgs field. In other words, like love and marriage, you can't have one without the other. The building blocks of our theories are fields and particlesThe rationale of describing particles instead of fields:
And, the workers at the LHC do not talk about colliding the quantum fields of two protons together to measure the wavelengths of some abstract wave oscillating in some imaginary aether. They speak of banging particles together and measuring the particles they see coming out. The point is, while our mathematical theories are expressed in terms of abstract fields, what we always measure is best described as particles.So, quantum fields are abstract mathematical constructs whereas quantum "particles" are real entities.
This is becoming a ‘how many angels fit on the point of a needle’ discussion.
Is light a particle? No, because in the two slit experiment on photon passes both slits, which a particle can’t. Is it a field? No, because the photon is measured locally.
The Higgs field was introduced to explain the mass of particles. However when there is a quantum field, then its excitation, the Higgs particle, must also exist. As you know it was found. As a result of ‘just a mathematical abstraction’?
The quantum mathematical formalism is consistent in itself and with experiment. So there is no scientific problem. The problem arises when we try to understand what happens based on concepts of our everyday life. They just do not fit. And so we can discuss endlessly about which concepts fit best.
What is a field in physics?
A field is a physical quantity that has a value for each point in space and time.This is so for the classical electromagnetic (EM) or the Newtonian gravitational fields. However:
....a field can be either a classical field or a quantum field, depending on whether it is characterized by numbers or quantum operators respectively.The consequence of defining a field as "numbers in space"
Defining the field as "numbers in space" shouldn't detract from the idea that it has physical reality. “It occupies space. It contains energy. Its presence eliminates a true vacuum." The field creates a "condition in space" such that when we put a particle in it, the particle "feels" a force.Bold added by me. This is true for the classical EM or gravitational fields. However, wrt the quantum field, where is the "particle"? Is it that the field is the "particle" or is it the epiphenomenon arising from the field? Whatever it is, the quantum field has no physical reality, unlike classical fields. For instance, has anyone observed a quantum field? From http://en.wikipedia.org/wiki/Quantum_field_theory
In theoretical physics, quantum field theory (QFT) is a theoretical framework for constructing quantum mechanical models of subatomic particles in particle physics and quasiparticles in condensed matter physics, by treating a particle as an excited state of an underlying physical field.Bold added by me. So, if "QFT is a theoretical framework for constructing quantum mechanicals models of subatomic particles" and as it is expressed in mathematical terms, it is a mathematical construct. A model is only "the map, but it is not the territory". OTOH, quantum "particles" exist and they can be observed i.e. they are real. That is the territory.
Lots of smart folks right here, but I was wondering if there are any good Physics forums where informed laymen like myself can ask questions but not be dismissed because I'm not an actual physicist?Depends on what what kind of physics your asking and what your question is. My physics professor actually warned me once to be very skeptical of physics websites and forums which try to help students get through undergrad physics. Many of them are often wrong. But of course, that isn't to deny that there are some good physics on the web somewhere
What is a field in physics? http://en.wikipedia.org/wiki/Field_(physics)
In the late 1920s, the new rules of quantum mechanics were first applied to the electromagnetic fields. In 1927, Paul Dirac used quantum fields to successfully explain how the decay of an atom to lower quantum state lead to the spontaneous emission of a photon, the quantum of the electromagnetic field. This was soon followed by the realization (following the work of Pascual Jordan, Eugene Wigner, Werner Heisenberg, and Wolfgang Pauli) that all particles, including electrons and protons could be understood as the quanta of some quantum field, elevating fields to the most fundamental objects in nature.Bold added by me.
From http://en.wikipedia.org/wiki/Quantum_field_theoryItalics added by me. Your bold phrases just say what is true for every theory in physics: that it is a model and theoretical framework. How many angels? Stop citing. Start thinking. When you know what you cite, you show you are thinking.In theoretical physics, quantum field theory (QFT) is a theoretical framework for constructing quantum mechanical models of subatomic particles in particle physics and quasiparticles in condensed matter physics, by treating a particle as an excited state of an underlying physical field.
Specifically, if quantum fields are "the most fundamental objects in nature" has anybody observed, detected and measured these ubiquitous quantum fields as can be done for EM fields? From the same wiki:In the late 1920s, the new rules of quantum mechanics were first applied to the electromagnetic fields. In 1927, Paul Dirac used quantum fields to successfully explain how the decay of an atom to lower quantum state lead to the spontaneous emission of a photon, the quantum of the electromagnetic field. This was soon followed by the realization (following the work of Pascual Jordan, Eugene Wigner, Werner Heisenberg, and Wolfgang Pauli) that all particles, including electrons and protons could be understood as the quanta of some quantum field, elevating fields to the most fundamental objects in nature.
Quantum fields It is now believed that quantum mechanics should underlie all physical phenomena, so that a classical field theory should, at least in principle, permit a recasting in quantum mechanical terms; success yields the corresponding quantum field theory.Bold added by me. Belief....at least in principle...seems like faith and religious dogma! :)
From http://en.wikipedia.org/wiki/Quantum_field_theoryItalics added by me. Your bold phrases just say what is true for every theory in physics: that it is a model and theoretical framework. A model and theoretical framework is precisely that: it is a map and not the territory. Maps can be useful, but we must not conflate the map with the territory. What is that "underlying physical field" i.e. the quantum field? Can we observe, detect and measure it as we can, with an EM field? If not, is it real, is it just a mathematical construct or what (whatever it is).In theoretical physics, quantum field theory (QFT) is a theoretical framework for constructing quantum mechanical models of subatomic particles in particle physics and quasiparticles in condensed matter physics, by treating a particle as an excited state of an underlying physical field.
How many angels?Not how many angels, more like how many epicycles.
Stop citing. Start thinking. When you know what you cite, you show you are thinking.Stop prejudicing, start thinking critically and remove the shackles of received wisdom. :lol:
This is becoming a 'how many angels fit on the point of a needle' discussion. Is light a particle? No, because in the two slit experiment on photon passes both slits, which a particle can't. Is it a field? No, because the photon is measured locally. The Higgs field was introduced to explain the mass of particles. However when there is a quantum field, then its excitation, the Higgs particle, must also exist. As you know it was found. As a result of 'just a mathematical abstraction'? The quantum mathematical formalism is consistent in itself and with experiment. So there is no scientific problem. The problem arises when we try to understand what happens based on concepts of our everyday life. They just do not fit. And so we can discuss endlessly about which concepts fit best.All arguments fall into how many angels can fit on the point of a needle, sooner or later. There is no avoiding it except by removing oneself from the discussion when it seems to be leaning in that direction. Once that happens there is no saving it in most cases. Lois
Why is wikipedia being quoted so much?
Wikipedia itself says:
Wikis, including Wikipedia and other wikis sponsored by the Wikimedia Foundation, are not regarded as reliable sources.
Why is wikipedia being quoted so much? Wikipedia itself says: Wikis, including Wikipedia and other wikis sponsored by the Wikimedia Foundation, are not regarded as reliable sources. http://en.wikipedia.org/wiki/Wikipedia:Reliable_source_examplesIntriguing question. Fundamentally, what is a source? http://en.wikipedia.org/wiki/Wikipedia:Identifying_reliable_sources Definition of a source
The word "source" when citing sources on Wikipedia has three related meanings: * the piece of work itself (the article, book); * the creator of the work (the writer, journalist), * and the publisher of the work (for example, Random House or Cambridge University Press). Any of the three can affect reliability. Reliable sources may be published materials with a reliable publication process, authors who are regarded as authoritative in relation to the subject, or both. These qualifications should be demonstrable to other people.As such, wikipedia and wikis are not reliable sources per se. However, from the same wiki:
Many Wikipedia articles rely on scholarly material. When available, academic and peer-reviewed publications, scholarly monographs, and textbooks are usually the most reliable sources. However, some scholarly material may be outdated, in competition with alternative theories, or controversial within the relevant field. Try to cite present scholarly consensus when available, recognizing that this is often absent. Reliable non-academic sources may also be used in articles about scholarly issues, particularly material from high-quality mainstream publications. Deciding which sources are appropriate depends on context. Material should be attributed in-text where sources disagree.Bold added by me. There are lists of sources below the end of most wiki articles which are referred to by [numbers] in the wiki article, as sources. Wrt wikis on the natural sciences: http://en.wikipedia.org/wiki/Wikipedia:Identifying_reliable_sources_(natural_sciences)
Wikipedia's science articles are not intended to provide formal instruction, but they are nonetheless an important and widely-used resource. Scientific information should be based on reliable published sources and should accurately reflect the current state of knowledge. Ideal sources for these articles include comprehensive reviews in independent, reliable published sources, such as reputable scientific journals, statements and reports from reputable expert bodies, widely recognized standard textbooks written by experts in a field, or standard handbooks and reference guides, and high-quality non-specialist publications. Although news reports are sometimes inappropriate as reliable sources for the technical aspects of scientific results or theories, they may be useful when discussing the non-technical context or impact of science topics, particularly controversial ones. The scope of this page is limited to the natural sciences, including astronomy, biology, chemistry, geoscience, physics, and interdiscliplinary fields.Bold added by me. What is a resource? http://www.merriam-webster.com/dictionary/resource
e : a source of information or expertiseOf course, there are other resources online but wikipedia has established itself as an accessible open and free resource (which is subject to constant discriminate revisions and updates). This is the strength of wikipedia, notwithstanding criticisms of it's perceived weakness in being open. Wikipedia depend on the the "wisdom of the crowd" for the reliability and accuracy of it's articles. http://en.wikipedia.org/wiki/Wisdom_of_the_crowd
The wisdom of the crowd is the process of taking into account the collective opinion of a group of individuals rather than a single expert to answer a question. A large group's aggregated answers to questions involving quantity estimation, general world knowledge, and spatial reasoning has generally been found to be as good as, and often better than, the answer given by any of the individuals within the group. An intuitive and often-cited explanation for this phenomenon is that there is idiosyncratic noise associated with each individual judgment, and taking the average over a large number of responses will go some way toward canceling the effect of this noise.[1] This process, while not new to the information age, has been pushed into the mainstream spotlight by social information sites such as Wikipedia and Yahoo! Answers, and other web resources that rely on human opinion.[2]In other words, there exist a "system of checks and balances" (negative and positive feedbacks) for these open systems which is the source of their strength and robustness, analogous to nature. Also, there is the issue of copyleft instead of copyright wrt wikis. http://en.wikipedia.org/wiki/Copyleft
In other words, copyleft is a general method for marking a creative work as freely available to be modified, and requiring all modified and extended versions of the program to be free as well.[1]This is the rationale behind why wikipedia is so often quoted.
Understandable.
But one must still go to the sources Wikipedia uses and then use them as sources.
Wikipedia itself is questionable
Understandable. But one must still go to the sources Wikipedia uses and then use them as sources.Not necessarily so. That depends on how deeply one wants to know about a topic and the time involved in order to do so. If one is not doing research but is curious about a particular topic, there is no necessity to do so. Consequently, one can rely on wikipedia as an accessible and valuable resource to inform and/or educate, without prejudice. Many wiki articles are comprehensive essays which are carefully written by experts and as such, are useful and helpful overviews on any particular topic for one to obtain knowledge without the necessity to tediously search for sources (of which some are not free or they are highly technical complex papers), understand and evaluate them to determine their reliability wrt other sources and then and only then, to cite them. OTOH, it is essential for one to learn and practice critical thinking rather than to look for, understand, evaluate and/or cite sources, with time constraints as the reality. http://en.wikipedia.org/wiki/Critical_thinking
Critical thinking is a way of deciding whether a claim is true, partially true, or false. Critical thinking is a process that leads to skills that can be learned, mastered and used. Critical thinking is a tool by which one can come about reasoned conclusions based on a reasoned process. This process incorporates passion and creativity, but guides it with discipline, practicality and common sense. It can be traced in the West to ancient Greece with its Socratic method and in the East to ancient India with the Buddhist kalama sutta and abhidharma literature. Critical thinking is an important component of education, politics, business, and science.Bold added by me.
Wikipedia itself is questionableGenerally, anything and everything, are questionable. Wikipedia and wikis are resources, not sources. As such, and for the reasons stated in my last post, they are valuable resources and should be evaluated/used appropriately.
Why is wikipedia being quoted so much? Wikipedia itself says: Wikis, including Wikipedia and other wikis sponsored by the Wikimedia Foundation, are not regarded as reliable sources. http://en.wikipedia.org/wiki/Wikipedia:Reliable_source_examplesThe reason Wikipedia is so often cited is beacuse it is handy, usually reliable and correctible. Wikipedia always gives the sources of what they are presenting, and they are usually scientific and scholarly sources. All you have to do is investigate those sources. It does no good to shoot the messenger. If you don't like Wikipedia, tell us about another source of information that is more reliable and as accessible as Wikipedia. It is no less reliable than any encyclopedia. Nobody with any sense would take Wikipedia to be the final word on anything. It represents a digest of current information. If you don't like it, point out specific errors in the sources. You sound as if you think Wikipedia is engaging some sort of conspiracy to spread misinformation. In that case, don't use it, don't read it and don't cite it. Get your information from elsewhere, but make sure you investigate all the sources. Wikipedia's statement is simply a disclaimer to avoid legal challenges. It's like a parking lot disclaimer that says they are not responsible for any losses. They ARE responsible for some losses but they prefer not to publicize that fact. Lois
What is an encyclopedia?
An encyclopedia (also spelled encyclopaedia or encyclopædia) is a type of reference work – a compendium holding a summary of information from either all branches of knowledge or a particular branch of knowledge.Examples of modern encyclopedias including wikipedia:
The modern encyclopedia evolved out of dictionaries around the 17th century. Historically, some encyclopedias were contained in one volume, but some, such as the Encyclopædia Britannica or the world's largest Enciclopedia universal ilustrada europeo-americana, became huge multi-volume works.Some modern encyclopedias, such as Wikipedia, are electronic and are often freely available.In the 21st century:
On-line encyclopedias offer the additional advantage of being dynamic: new information can be presented almost immediately, rather than waiting for the next release of a static format, as with a disk- or paper-based publication. The 21st century has seen the dominance of wikis as popular encyclopedias, including Wikipedia among many others.Bold added by me. Here is a list of online encyclopedias: http://en.wikipedia.org/wiki/List_of_online_encyclopedias Some good online encyclopedias are not free for full access, except for a free trial or become defunct. OTOH, wikipedia allows free full access to the wikis with copyleft and as such, it is the online encyclopedia par excellence.