• Physics Discussion
    973 replies, posted
Relevant to physics [I]and[/I] math: [url]http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.118.130201[/url]
Reading the abstract with my (very) limited math knowledge, I got that they are almost there on proving the Riemann Hypothesis, if that is right, it sounds very exciting!
I don't think I've come across this thus far, what are the consequences of the paper and thus the impact of the Riemann Hypothesis? Seems very number-theory based but can't immediately see the consequences on Physics - something Statistical Mechanics-y?
[QUOTE=Cosa8888;52039366]Reading the abstract with my (very) limited math knowledge, I got that they are almost there on proving the Riemann Hypothesis, if that is right, it sounds very exciting![/QUOTE] I don't know if I'd say they're almost there. It's a nice heuristic to believe the hypothesis is true, but we have those already. It still needs to be made rigorous. [editline]3rd April 2017[/editline] [QUOTE=Instant Mix;52053264]I don't think I've come across this thus far, what are the consequences of the paper and thus the impact of the Riemann Hypothesis? Seems very number-theory based but can't immediately see the consequences on Physics - something Statistical Mechanics-y?[/QUOTE] The "Relation to Quantum Mechanics" section on page 4 talks about that a bit. I doubt there will be much impact on physics, it's more of a physics-inspired heuristic/possible avenue for proof.
guys I need to do a final project for my computational physics course. I want to do something with cellular automata that isn't percolation related because that's boring. If I can make the abstract before the weekend (when the abstract is due) I can submit it to a computational physics conference and attend with a poster.
[QUOTE=Garry #2;52053641]guys I need to do a final project for my computational physics course. I want to do something with cellular automata that isn't percolation related because that's boring. If I can make the abstract before the weekend (when the abstract is due) I can submit it to a computational physics conference and attend with a poster.[/QUOTE] Oh lovely, another Comp. Physicist. Can't say I'm particularly versed with cellular automata so anything I suggest would probably have already been considered by yourself..
[QUOTE=Instant Mix;52053674]Oh lovely, another Comp. Physicist. Can't say I'm particularly versed with cellular automata so anything I suggest would probably have already been considered by yourself..[/QUOTE] Nice! Are you still a student? Never know, maybe I haven't considered what you're thinking. Shoot
[QUOTE=Garry #2;52053760]Nice! Are you still a student? Never know, maybe I haven't considered what you're thinking. Shoot[/QUOTE] Almost finishing my Junior Honours year, wasn't a particularly fun one apart from some quantum computing assignment. Can't say I'm actually really versed on the subject itself, so I can't really give a valid example! Would've suggested attempting to simulate the evolution of an automata system via a neural network based on a normal system, but realised you're wanting to deal with the outcome of the automata ( I think?)
Not really sure where else to ask but you guys seem the most[I] science-y[/I]: Are there time based rules on when research goes public? Like for copywright, you can own that intellectual property for a certain amount of time, and with research papers and articles, you have to go through a paywall. After a certain amount of years, does that research go public or is it forever pay-walled?
I think that highly depends on the type of research as well as the publisher. Usually they're greedy cunts and they'll paywall stuff even if it's 100+ years old (e.g. [URL="http://onlinelibrary.wiley.com/doi/10.1002/andp.v322:10/issuetoc"]the Annals of Physics 1905[/URL])... There's ways around it but I don't know if linking those is counted as warez...
Can someone point me to a good guide on why neutrons have a short half-life when not part of a nucleus?
I wonder if space and time can be converted to energy or if there's any relation between them? It makes sense to me because you have to use energy for mass to move across space and more energy is needed for mass to go faster, therefore less time.
[QUOTE=chocolatedrop;52154310]I wonder if space and time can be converted to energy or if there's any relation between them? It makes sense to me because you have to use energy for mass to move across space and more energy is needed for mass to go faster, therefore less time.[/QUOTE] How would you convert space to energy? One argues that energy is required to transfer information; moving things faster requires more energy but it's a fallacy to imply that due to that, time can be converted to energy.
So, a thought struck me about a month ago, and now I figured I want a second opinion to set me straight in terms of which physic rules one can and can't apply. So, to start off, my hypothesis would be anti-matter whether it exists and how I think you can find it (maybe). We don't know for sure if it exists or not, but logic dictates that for something to exist there must be some sort of count-part for it, right? Matter is everywhere with a gravity pulling downwards. So my theory on anti-matter would be that it's gravity field would be pulling upwards. If that's the case, then perhaps that's why the universe is expanding, and why it's accelerating faster as time goes by. (Just like a boulder down a hill, it keeps gaining more momentum the longer it travels) So somewhere we should be able to find a pattern of this - somehow using a calculation on where stars gets pulled away from different location. They must then all be going in the opposite direction of where the anti-matter is located at. I don't know if observing many different stars many light-years apart, can truly measure their path due to the distance from the stars to us. I have no background in physic whatsoever, I'm just genuinely curious as to how things go around in our universe. Is my thought-process even slightly viable or is it all to be considered impossible due to facts that I am simply unaware of?
[QUOTE=Ponator;52199383]So, a thought struck me about a month ago, and now I figured I want a second opinion to set me straight in terms of which physic rules one can and can't apply. So, to start off, my hypothesis would be anti-matter whether it exists and how I think you can find it (maybe). We don't know for sure if it exists or not, but logic dictates that for something to exist there must be some sort of count-part for it, right? Matter is everywhere with a gravity pulling downwards. So my theory on anti-matter would be that it's gravity field would be pulling upwards. If that's the case, then perhaps that's why the universe is expanding, and why it's accelerating faster as time goes by. (Just like a boulder down a hill, it keeps gaining more momentum the longer it travels) So somewhere we should be able to find a pattern of this - somehow using a calculation on where stars gets pulled away from different location. They must then all be going in the opposite direction of where the anti-matter is located at. I don't know if observing many different stars many light-years apart, can truly measure their path due to the distance from the stars to us. I have no background in physic whatsoever, I'm just genuinely curious as to how things go around in our universe. Is my thought-process even slightly viable or is it all to be considered impossible due to facts that I am simply unaware of?[/QUOTE] We know for sure anti-matter exists, it has been produced in labs and its decay particles and quarks are found in the experiments at CERN. What you are describing though, something which has a repulsive effect due to mass rather than an attraction - are the effects of dark matter, rather than anti-matter. We can't really pinpoint masses of dark matter because it's virtually impossible to detect - how can we conclude that a moving object is such due to a repulsive or attractive force and as such whether to consider it being affected by dark matter, and if the matter is invisible to most forms of observation, how can we distinguish it from the vacuum of space? You would be partially correct though; it's a common hypothesis in the field that dark matter is responsible for the expansion of the universe; but as dark matter is still a technically hypothetical type of matter, we can't say for sure that it is the sole reason
Thank you very much for the clarification. In my head those words should be swapped around, but I guess I have to look into what anti-matter is used for exactly. Does that mean we can have like a periodic table, only like reversed though? I agree it can't be observed by vision nor have we spotted anything with our wide arrange of equipment's. But since dark matter have a repulsive effect as you describe (pushing) wouldn't we somehow see a big (really big) empty space somewhere? That's nice to know my hypothesis is valid, granted I'm not an physicist.
[QUOTE=Ponator;52199694]Thank you very much for the clarification. In my head those words should be swapped around, but I guess I have to look into what anti-matter is used for exactly. Does that mean we can have like a periodic table, only like reversed though? I agree it can't be observed by vision nor have we spotted anything with our wide arrange of equipment's. But since dark matter have a repulsive effect as you describe (pushing) wouldn't we somehow see a big (really big) empty space somewhere? That's nice to know my hypothesis is valid, granted I'm not an physicist.[/QUOTE] I couldn't comment on the first; however each quark has an antiquark; and in turn protons, electrons, etc. have opposites such as anti-protons and positrons. Yes, you could argue that each element has an anti-twin and as such an anti-periodic table could be created ( however that'd be a bit pointless as it would have virtually no use as antimatter is fucking difficult to produce; and one can garner the properties of the antiparticle from the properties of the normal particle ). We have yet to observe complex antielements due to their rarity and difficulty to produce however. What I was trying to imply is that a large empty space does not necessarily imply that it's filled with dark matter. When you look at smaller situations, like dropping a ball, you can make a fairly correct prediction that the net force on that ball is due to an attractive force towards the earth. However, you could also technically argue that the force on it is due to some repulsive force in the opposite direction. Because an object is undergoing a force or movement, you can't determine exactly that the effect causing this is repulsive or attractive; and as such you can't necessarily say that any empty areas around moving planets are filled or contain dark matter. We do see large empty spaces in the universe; but again; we can't explicitly determine whether this is because matter has been repulsed from this area, or it has been attracted to more massive objects surrounding it.
[QUOTE=Instant Mix;52199015]How would you convert space to energy? One argues that energy is required to transfer information; moving things faster requires more energy but it's a fallacy to imply that due to that, time can be converted to energy.[/QUOTE] Ideally, one would like to develop a physical model from which both spacetime and matter dynamically emerge. Given the link between gravity, matter, and geometry it wouldn't be too surprising for spacetime and matter to both emerge from the same underlying thing. One of my supervisor's colleagues, [URL="https://en.wikipedia.org/wiki/Sundance_Bilson-Thompson"]Sundance Bilson-Thompson[/URL], came to visit my university a week or so ago and we had a chat about what he's working on. He's working on trying to see how much (if any) of the standard model of particle physics can be made to emerge out of loop quantum gravity. So far he's not got any dynamics in the model that he's working on, but if you take the ideas of loop quantum gravity seriously and imagine there to be some underlying graph from which spacetime emerges, it seems like you can construct what looks like the first generation of leptons from topological degrees of freedom of the graph.
[QUOTE=Instant Mix;52201028]I couldn't comment on the first; however each quark has an antiquark; and in turn protons, electrons, etc. have opposites such as anti-protons and positrons. Yes, you could argue that each element has an anti-twin and as such an anti-periodic table could be created ( however that'd be a bit pointless as it would have virtually no use as antimatter is fucking difficult to produce; and one can garner the properties of the antiparticle from the properties of the normal particle ). We have yet to observe complex antielements due to their rarity and difficulty to produce however. What I was trying to imply is that a large empty space does not necessarily imply that it's filled with dark matter. When you look at smaller situations, like dropping a ball, you can make a fairly correct prediction that the net force on that ball is due to an attractive force towards the earth. However, you could also technically argue that the force on it is due to some repulsive force in the opposite direction. Because an object is undergoing a force or movement, you can't determine exactly that the effect causing this is repulsive or attractive; and as such you can't necessarily say that any empty areas around moving planets are filled or contain dark matter. We do see large empty spaces in the universe; but again; we can't explicitly determine whether this is because matter has been repulsed from this area, or it has been attracted to more massive objects surrounding it.[/QUOTE] I kind of get it now, thanks. Like in the beginning there were created bot matter and anti-matter, but since then anti-matter have been nullified due to the mass amount of matter around us. Like when the big bang occurred the universe was so dense that they all collided into each other thus picking it's winner as being matter - in this matter hehe. So by re-creating an antimatter electron, we simply proved this thesis to be true thus making it a theory. But it's not something we will keep creating because it's basically hard and unnecessary at this given time. Alright, so we basically need something to measure a force's origin, sort of. Can't specific mathematically methods be used to determine such a thing? We can measure matters effect on gravity, which is an effect caused by attraction and an asteroid can be measured due to it's constant orbit repetition.
[QUOTE=Ponator;52203915]I kind of get it now, thanks. Like in the beginning there were created bot matter and anti-matter, but since then anti-matter have been nullified due to the mass amount of matter around us. Like when the big bang occurred the universe was so dense that they all collided into each other thus picking it's winner as being matter - in this matter hehe. So by re-creating an antimatter electron, we simply proved this thesis to be true thus making it a theory. But it's not something we will keep creating because it's basically hard and unnecessary at this given time. Alright, so we basically need something to measure a force's origin, sort of. Can't specific mathematically methods be used to determine such a thing? We can measure matters effect on gravity, which is an effect caused by attraction and an asteroid can be measured due to it's constant orbit repetition.[/QUOTE] Unfortunately this in point in which your previous statement, that you don't have a background in physics, begins to become detrimental. You seem incredibly interested in it though; I'd highly recommend reading books about the subject. If you take an even keener interest, have a scour of youtube; and if you're up for it, give walter lewin's lectures a shot.
Yeah, alright. I have always lacked the fundamental understanding of mathematics. I can't get my head wrapped around all those numbers somehow. Is there a good book in physics for the common man? Something written like Stephen Hawkins book of Black Holes if you have read that particular book. (I can't remember it's exact name though) I've seen one of Walter's lectures and he is indeed a great educator.
To follow up on you both, Ponator and Instant Mix, there is a theory out there on anti-matter having an opposite gravity "charge" just like how electric charge can be positive or negative. It's by a retired CERN physicist and has pretty elegant explanations for dark matter, inflation theory, and a few other things while only using Standard Model particles. I really like this theory since like any good one it explains multiple phenomenon with a single assumption which is testable in the next decade. There [I]are[/I] techniques to address the problems of measuring forces yall describe, which would be used to figure this out. It also has a different model for the big bang that necessitates a cyclical universe. As far as I know there is no evidence or any arguments against the theory as of now. I can link it for anyone interested. Ponator, we create antimatter particles all the time and will continue to do so. It's difficult but necessary for some high energy physics. It's hard, but not nearly the hardest part of high energy physics. BUT, the fact that antimatter exists doesn't mean that a big bang event happened how most people think it did. As with the model I describe, there are different ideas of how the universe arose. It's too complicated of a system to look at one aspect of it, antimatter vs matter, and think you've solved the puzzle. Theories become theories by being able to answer many problems thoroughly, and with a system so complex you need to take much more into account.
[QUOTE=DOG-GY;52207425]To follow up on you both, Ponator and Instant Mix, there is a theory out there on anti-matter having an opposite gravity "charge" just like how electric charge can be positive or negative. It's by a retired CERN physicist and has pretty elegant explanations for dark matter, inflation theory, and a few other things while only using Standard Model particles. I really like this theory since like any good one it explains multiple phenomenon with a single assumption which is testable in the next decade. There [I]are[/I] techniques to address the problems of measuring forces yall describe, which would be used to figure this out. It also has a different model for the big bang that necessitates a cyclical universe. As far as I know there is no evidence or any arguments against the theory as of now. I can link it for anyone interested. Ponator, we create antimatter particles all the time and will continue to do so. It's difficult but necessary for some high energy physics. It's hard, but not nearly the hardest part of high energy physics. BUT, the fact that antimatter exists doesn't mean that a big bang event happened how most people think it did. As with the model I describe, there are different ideas of how the universe arose. It's too complicated of a system to look at one aspect of it, antimatter vs matter, and think you've solved the puzzle. Theories become theories by being able to answer many problems thoroughly, and with a system so complex you need to take much more into account.[/QUOTE] Sounds really interesting, especially if it insinuates a cyclical universe which seems fairly counterintuitive given the observed expansion of the universe. Please link it!
[QUOTE=Instant Mix;52208887]Sounds really interesting, especially if it insinuates a cyclical universe which seems fairly counterintuitive given the observed expansion of the universe. Please link it![/QUOTE] Here's a paper and a slideshow from a talk: [url]https://arxiv.org/abs/1405.5792[/url] [url]https://indico.cern.ch/event/361413/contributions/1776293/attachments/1135100/1623933/WAG_2015_UCL_Hajduk.pdf[/url] I [I]really[/I] like this idea. From the understanding of physics I have, not super deep but definitely a lot more than most people, it seems pretty damn sound and is certainly testable as he points out, so I find this fascinating and hopefully promising. He does address the observed expansion and it fits within the theory. Basically the expansion we see holds for now, but under this theory will change as it continues. Really cool how he explains it all, especially without needing tons of hypothetical stuff. If any the well studied peeps in this thread have holes to poke here I'd be super interested in learning more.
I've a quantum mechanics exam tomorrow. If I do so much as even pass by the skin of my teeth, I will be unbelievably happy.
Almost completed my first year in physics now and I've liked it so far. Can't say I've given it my 100% considering I got 2's and barely passed the courses on electricity and electromagnetism... Already looking towards the master's degree years and the particle/nuclear physics program.
IMO the master years are more fun, much more choices and you start to figure out which direction you want to go.
What do you mean by "double angle effect?"
I'm hoping someone might be able to help me. I've got an assignment for engineering maths I'm doing. I've got to figure out the moment of inertia of of several solids and then do some stuff with them. There's a section in Calculus (Stewart) that discusses MoI but for some reason it's saying that the mass of the solid (in this case a disk) is area*density... which just doesn't make sense. I'm probably missing something really stupid and/or simple. It's on page 1031 of the seventh edition for anyone who has a copy.
[QUOTE=download;52326709]I'm hoping someone might be able to help me. I've got an assignment for engineering maths I'm doing. I've got to figure out the moment of inertia of of several solids and then do some stuff with them. There's a section in Calculus (Stewart) that discusses MoI but for some reason it's saying that the mass of the solid (in this case a disk) is area*density... which just doesn't make sense. I'm probably missing something really stupid and/or simple. It's on page 1031 of the seventh edition for anyone who has a copy.[/QUOTE] For a (non-zero volume) cylinder you would have area[m^2]*density[kg m^-3] height [m] = mass [kg]. For a disk, the result is area[m^2] * density [kg m^-3] = "linear mass density" [kg m^-1]. So if you had a wire with a cross-section like that disk, you could calculate the mass of a wire of some length l as follows: linear mass density [kg m^-1] * length [m] = mass of the entire wire [kg] If this linear mass density is called mu, then we could say that this disk (or an infinitely thin cylinder): dm = mu dz. So I think the author implicitly left out the dz and just called dm (an infinitesimal mass of a cylinder) "the mass of a disk". I think it's a bit shaky in terms of units, or at least it could use some clarification. The example, for reference: [img]http://i.imgur.com/XcJEtIy.png[/img]
Sorry, you need to Log In to post a reply to this thread.