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oquen
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Is dark matter physics considered a low or high energy physics, and why?
phinds said:What do you think and why?
rootone said:What do you mean by low energy?
Low energy means that nothing nothing interesting changes, things don't interact much.
oquen said:There is a subforum called High Energy, Nuclear and Particle Physics.
What falls under Low Energy Physics then?
nikkkom said:There is no "Low Energy Physics".
"High Energy Physics" is actually a misnomer, originating from the time when ~1GeV energies were considered big for a single particle. In fact, High Energy Physics means "smallest scale physics", a branch of physics which studies elementary particles.
nikkkom said:It's all "High Energy Physics".
One step lower from it is chemistry.
nikkkom said:It's all "High Energy Physics".
One step lower from it is chemistry.
I don't see how this discussion applies to the topic at hand. It's a pretty speculative discussion about what might lie beyond the standard model.oquen said:I think you are mistaken. See this thread of the conversations between seasoned Science Advisors: https://www.physicsforums.com/threads/new-experiments-supporting-bohmian-mechanics.913098/page-2 message 27 & 28
vanhees71: Of course, the theory breaks down at very high energies, when you come close to the Landau pole, but you are in the realm of relativistic physics at much lower energy scales than that.
atyy: If the theory breaks down at high energies, then we can consider the possibility that the low energy relativistic theory - including the Lamb shift - emerges from a non-relativistic high energy theory.
nikkkom... if the words "low energy" doesn't exist.. why would they use them? Or maybe there are two meanings of "High Energy".. one about scales where closer to the Landau pole would be High Energy. The other meaning would be the accelerator energies? Are you referring only to the latter? please clarity, and others too. Thanks!
kimbyd said:I don't see how this discussion applies to the topic at hand. It's a pretty speculative discussion about what might lie beyond the standard model.
As far as we know, our current model of high-energy physics is exceedingly accurate everywhere (except for systems where self-gravity is a significant component). Relativistic physics reduces to non-relativistic physics in the appropriate limit. Quantum physics reduces to classical physics in the appropriate limit. The standard model is the most accurate theory of the behavior of small things that we have at present. Its application to larger systems (but not large enough for self-gravity to be important) is only really limited by the excessive computational difficulty of applying the theory.
oquen said:If i'll write an article.. which should I follow..
PeterDonis said:We can't answer that question here. The terms "high energy physics" and "low energy physics" don't have standard definitions. You can define them however you like, as long as you make your definitions clear. In other words, this thread appears to be about terminology, not physics.
Which leads to the obvious next question: do you have a question about physics?
oquen said:The thread title is the question.. Is Dark Matter physics low or high energy physics?
oquen said:what MeV, GeV, or TeV are the scale of dark matter?
We're understanding you. We're saying that your categorization does not exist.oquen said:You still can't understand my questions. Let me illustrate it by means of definition...
PeterDonis said:That's a question about terminology, not physics.
That's a question about physics. The short answer is that we don't know because we don't know what dark matter is. All we know is that it's not one of the Standard Model particles.
A longer answer requires getting more specific about what this "energy scale" actually means. There are at least two factors involved: the mass of the particle, and the strength of the interactions it has with other particles. For example, photons are massless, and they're easy to detect because they are involved in the electromagnetic interaction, which is strong enough that it has all sorts of observable effects in experiments even at room temperature. The weak gauge bosons are quite massive as elementary particles go, plus their interactions are not as strong as EM, so you need to run pretty high energy experiments to detect them, at least directly. (Note that there was considerable indirect evidence for them from lower energy experiments well before they were directly detected.) But neutrinos, for example, are very light (we know now they're not massless, but their masses are very small as elementary particle masses go), but they're still hard to detect because they interact so weakly with anything else. The interactions themselves are not very high energy--you don't need a particle accelerator to detect neutrinos (the Kamiokande experiments for detecting solar neutrinos are just large tanks of liquid at more or less room temperature)--but they're so weak that they happen very rarely.
The problem with dark matter is that we don't know which of the last two reasons (large mass or very weak interactions) is the reason we haven't directly detected particles that match its properties. Is it because they are very massive particles (for example, supersymmetric partners of one or more of the Standard Model particles)? Or is it because they're so weakly interacting (for example, very small mass like neutrinos plus no interactions other than gravity)? We don't know.
Because the Standard Model, our current best-fit model, cannot describe things that happen above somewhere between a few hundred GeV and a few TeV. Physicists want to discover how to accurately describe the universe at these higher energy levels. This includes discovering the nature of dark matter, how gravity and quantum mechanics interact, and number of other unanswered questions.oquen said:In this theoretical probing business of the Planck scale.. do we wish to probe it because we want to create Planck mass or we want to see how the inside of the Planck interacts with the wavelength probe (theoretically because I know it's hard to probe the Planck scale)?
PeterDonis said:That's a question about terminology, not physics.
That's a question about physics. The short answer is that we don't know because we don't know what dark matter is. All we know is that it's not one of the Standard Model particles.
A longer answer requires getting more specific about what this "energy scale" actually means. There are at least two factors involved: the mass of the particle, and the strength of the interactions it has with other particles. For example, photons are massless, and they're easy to detect because they are involved in the electromagnetic interaction, which is strong enough that it has all sorts of observable effects in experiments even at room temperature. The weak gauge bosons are quite massive as elementary particles go, plus their interactions are not as strong as EM, so you need to run pretty high energy experiments to detect them, at least directly. (Note that there was considerable indirect evidence for them from lower energy experiments well before they were directly detected.) But neutrinos, for example, are very light (we know now they're not massless, but their masses are very small as elementary particle masses go), but they're still hard to detect because they interact so weakly with anything else. The interactions themselves are not very high energy--you don't need a particle accelerator to detect neutrinos (the Kamiokande experiments for detecting solar neutrinos are just large tanks of liquid at more or less room temperature)--but they're so weak that they happen very rarely.
The problem with dark matter is that we don't know which of the last two reasons (large mass or very weak interactions) is the reason we haven't directly detected particles that match its properties. Is it because they are very massive particles (for example, supersymmetric partners of one or more of the Standard Model particles)? Or is it because they're so weakly interacting (for example, very small mass like neutrinos plus no interactions other than gravity)? We don't know.
oquen said:There is an irony in this last paragraph. Dark matter is supposed to be so weak interacting with our normal matter.. so we assume dark matter has so few mass. yet it is possible they are very massive particles (for example supersymmetric partners of one or more of the Standard Model particles). Does the dark matter appearing low mass is after supersymmetry breaking or prior? In other standard model particles. What particle appear in different mass before and after symmetry breaking? I'm trying to think of the analogy.
I wonder if another particle that is very massive yet not so massive.
oquen said:I think you are mistaken. See this thread of the conversations between seasoned Science Advisors: https://www.physicsforums.com/threads/new-experiments-supporting-bohmian-mechanics.913098/page-2 message 27 & 28
vanhees71: Of course, the theory breaks down at very high energies, when you come close to the Landau pole, but you are in the realm of relativistic physics at much lower energy scales than that.
atyy: If the theory breaks down at high energies, then we can consider the possibility that the low energy relativistic theory - including the Lamb shift - emerges from a non-relativistic high energy theory.
nikkkom... if the words "low energy" doesn't exist..
oquen said:Dark matter is supposed to be so weak interacting with our normal matter.. so we assume dark matter has so few mass
Dark matter is a hypothetical form of matter that does not emit or interact with electromagnetic radiation, making it invisible to traditional telescopes. It is believed to make up about 27% of the universe and plays a crucial role in the formation and evolution of galaxies. Studying dark matter can help us better understand the structure of the universe and the laws of physics that govern it.
This is a matter of debate among scientists. Some argue that dark matter should be considered a low energy phenomenon since it does not interact with light or other forms of radiation. Others argue that it should be classified as high energy physics because it is thought to interact with other particles through gravity and may have a significant impact on the formation of structures in the universe.
Currently, there is no direct way to observe dark matter. Instead, scientists use various indirect methods such as studying the effects of dark matter on the rotation of galaxies, gravitational lensing, and particle colliders to try to detect and understand its properties.
There are several theories that attempt to explain the nature of dark matter. Some propose that it is made up of Weakly Interacting Massive Particles (WIMPs), while others suggest it could be composed of axions, sterile neutrinos, or other exotic particles. Another theory, known as Modified Newtonian Dynamics (MOND), suggests that dark matter does not exist and that our understanding of gravity needs to be revised.
At this time, there are no known practical applications for dark matter. However, studying it could lead to a better understanding of the universe and potentially help us develop new technologies or improve our understanding of fundamental physics principles.