Pair Definition and 379 Threads

If you think of electrons with spin as bar magnets, you know bar magnets of opposite polarity when put next to each other in any respective rotation don't cancel each other's magnetic field out. So what's a more apt analogy for electron paired have no magnetic field?

The first one a M7.1 in the Kermadec Isl. region north of New Zealand M 7.1 - Kermadec Islands, New Zealand 2023-04-24 00:41:55 (UTC) 29.968°S 177.826°W 43.1 km depth It was followed by a couple of M5+ and a couple of M4.9 events. The Fault Plane Solution "beachball" shows a subduction (...

Can entanglement be detected in a single Bell pair? The canonical answer is NO, you can only see the entanglement in an ensemble of Bell pairs. For example, you could look at a stream of photon pairs coming from a PDC source. If you apply the CHSH formula (usually presented as an "S" value)...

How does the formation of electron positron pairs increase the energy density and softens the EOS? I trrying to understand the pair instability supernova. In many texts and articles, it is written that the formation of electron positron pairs lead to instability, the energy density is increased...

Hi Pfs, consider a pair of maximally entangled photons where the total momentum is null and the same thing for the total angular momentum. I suppose that this pair is like an universe: nothing outside the pair acts on it except maybe a device for the measurement of these two properties (no local...

Does anyone happen to know if there's a grinder flange pair, i.e. its spacer and fastener flanges, with 3/8" x 24UNF thread instead of M10 x 1.5?

I am reading the following article on Kirkendall effect leading to the Formation of a hollow binary alloy nanosphere: a kinetic montecarlo study. I am unable to understand or find in references the reasoning to obtain equation (1):

In Kaur, M., Singh, M. Quantum double-double-slit experiment with momentum entangled photons. Sci Rep 10, 11427 (2020). https://doi.org/10.1038/s41598-020-68181-1 and in C. K. Hong and T. G. Noh, "Two-photon double-slit interference experiment," J. Opt. Soc. Am. B 15, 1192-1197 (1998) it is...

Hello all, I would like to check my understanding and get some assistance with last part of the following question, please. For part (d), would I use f(x | y) = f(x, y) / f(y) ? Problem statement: My attempt at a solution, not too confident in my set-up for part (d). I drew a sketch of the...

I know there have been a number of previous threads discussing the work of Pavel Kroupa, and this work has generally been categorized as far out of mainstream because it deals with his views on alternative gravity theories and so forth. However, I have come across two of his papers that describe...

How did you find PF?: a web search on an item I am fact-checking. I have very little background in physics specifically. I do have a thirst for knowledge. I seek treasures in many places, when I find one I attempt to correlate and ingrate it with other tidbits I have found. I have more of a...

***Title should read: ``Is it appropriate to include more than one instance of a prose-dialogue pair in each prose-dialogue block?'' instance of `prose-dialogue pair'? I don't know what they're called, actually, so I'll give an example of what I mean. "Hello Bob," said Sally. "How is the...

As far as I can tell, the shape looks like a cuboid with 8 arms pointing in all directions.

$$(1+i)z+(2-i)w=3+4i$$ $$iz+(3+i)w=-1+5i$$ ok, multiplying the first equation by##(1-i)## and the second equation by ##i##, we get, $$2z+(1-3i)w=7+i$$ $$-z+(-1+3i)w=-5-i$$ adding the two equations, we get ##z=2##, We know that, $$iz+(3+i)w=-1+5i$$ $$⇒2i+(3+i)w=-1+5i$$...

When we read about the mass transfer between neutron star pairs in a binary system, how is it that the one receiving the matter can increase its spin rate. Adding mass to a spinning object ought to slow due to conservation of momentum. Where does the energy come from?

Hello . The goal is to look for what force F I need to apply in order to return the arms to the closed position. Attached is a schema in the hope that my purpose will be understood I want to know what forces are acting on the system of the arms as well as the springs Many thanks in advance

Does there have to be both a salt and the conjugate acid/base of the anion/cation to create a buffer? Or can just a salt (e.g. ammonium formate) be a buffer? Does a buffer require a salt that contains the same conjugate base as the acid, or not necessarily? Thanks.

Can light make two pairs? (assuming enough energy to make two pairs) If so, why? or If not, why not?

Summary:: probability, Probability and Combinatorics Hello, I need someone to check If I correctly analized the probability of the following event: A group of younglings formed by 5 girls and 5 boys, Is going to divide in two teams of 5 elements each to play a game. a) suposing that the...

Hi! I've been browsing the internet for information about supernovae and I came across this chart describing 4 types of core collapse causes (the chart may have copied weirdly because not all the information fits into this text box): Cause of collapse Progenitor star approximate initial mass...

Hi all. I have been reading the following article and have a couple of basic questions about the decay of the Higgs into photons process - https://www.physicsforums.com/insights/lhc-part-4-searching-new-particles-decays/ As i understand this decay - the photons will have the same frequency and...

Dear Physicsforum Mentors, For a pinion and gear wheel, the face width instead of 12mm for both, it should be 14mm and 12mm. The explanation I got is, when there's 0.2mm deviation in axial, then only 11.8mm width will be in meshing. later, when the system be worn out, that 0.2mm will be in...

If we have a photon being converted to a positron-electron pair, but we lack enough energy for this to happen (hv<2Me*c^2) but the difference is smaller than the uncertainty amount, such that tunneling may be possible, would the resultant pair have net negative energy? Would tunneling even be...

I was reading this: http://www.physics-astronomy.com/2020/04/set-your-alarm-jupiter-venus-and-moon.html It seems that for this to happen the Moon would need to be in-between the pair of planets and the Sun - but the Sun's path defines the Ecliptic, and the bright planets are all very close to...

Good afternoon folks, I have a pair of ODE's which I would like to solve. Firstly i'd want to correctly identify the problem and then find the best method for finding a solution. \begin{align} \frac{dP_{(z,t)}}{dz} &= An_{(z,t)}P_{(z,t)}-BP_{(z,t)}...

Conservation of Energy: 9GeV + E = 5.3GeV + 5.3GeV Therefore E = 1.6GeV for the threshold energy. How would I find the velocity of B0 mesons so that I can calculate their mean distance? Then it would just be distance = velocity of b0 * mean proper lifetime Right?

Hi, These questions may seem basic, yet, I do not have an answer for that. The density of electrons and the density of holes in an intrinsic semiconductor are equal at equilibrium. From this, it seems that holes are simply lack of electrons that are given enough (thermal) energy to escape...

Let say we have two line ##a_1x+b_1y+c_1=0## and ##a_2x+b_2y+c_2=0##. Then pair of straight line equation is ##a_1a_2x^2+(a_1b_2+b_1a_2)xy+b_1b_2y^2+(a_1c_2+c_1a_2)x+(b_1c_2+c_1b_2)y+c_1c_2=0## i.e ##ax^2+2hxy+by^2+2gx+2fy+c=0## Now if we take ##a_1=0##, then the first line becomes...

While determining the condition for the pair of straight line equation ##ax^2+2hxy+by^2+2gx+2fy+c=0## or ##ax2+2(hy+g)x+(by^2+2fy+c)=0 ## (quadratic in x) ##x = \frac{-2(hy+g)}{2a} ± \frac{√((hy+g)^2-a(by^2+2fy+c))}{2a}## The terms inside square root need to be a perfect square and it is...

Hello, I want to see word problems on pair of straight lines to know the real-time applications. I want to find out what it means if a straight line intersects/is parallel to other straight line. Thanks!

We know that an electron and a positron will annihilate and emit gamma ray. But the electron and positron possesses initial kinetic energy meaning that it is difficult for them to really collide in each other. Just like Earth is not dropping into the Sun even with the gravitational pull. So I am...

I've managed to stump myself in attempting to answer a member on another forum. He is attempting to demonstrate length contraction using two electrons a known distance apart and moving at a known velocity.My thought experiment is based on his proposal; that's why I've chosen the components I...

The force of repulsion between two identical point charges when kept with a separation r in air is F. Half the gap between the two charges is filled by a dielectric slab of dielectric constant K=4. What is the new force of repulsion between the two charges? This is the question. Now if I solve...

Finding all natural number ordered pair $(x,y)$ for which $\displaystyle \binom{x}{y} = 2020.$

Homework Statement The number of ways to choose a pair of distinct numbers a and b from the set {1, 2, 3, ...49} such that |a - b| ≤ 3 is a. 141 b. 144 c. 147 d. 150 e. none of the above Homework Equations not sure The Attempt at a Solution Is a = 41 and b = 42 considered the same as a = 42...

Hi, Suppose I had a pair of protons that are entangled, and one or both of those protons decayed( https://en.wikipedia.org/wiki/Proton_decay ) over time, does that mean the entanglement between the protons does not exist anymore, and would it be fair to say that the entanglement decayed over time?

Homework Statement Prove that there exists a pair of consecutive integers such that one of these integers is a perfect square and the other is a perfect cube. Homework EquationsThe Attempt at a Solution I got 0 for perfect square and 1 for perfect cube. Is this a trick or something? Maybe...

Homework Statement What is the minimal amount of energy that a photon needs to create a muon pair? What is the wavelength of an electron with the same total energy? Tip: Muons have a rest mass of 1.9*10^-28kg and electrons 9.1*10^-31. The Attempt at a Solution I tried to use this formula...

I am not sure this question has been asked here before but I am curious about it. From the Modern Physics Course, I learned that we need a nucleus to create an electron and positron pair (with a photon). And the reason is stated as to conserve linear momentum. If this is the case then how the...

What is the probability that an electron will be annihilated by a virtual electron-positron pair?

Homework Statement One of the reasons a single photon could not produce an odd number of electrons and positrons is a) energy would not be conserved b) unattainable photon energies would be needed c) matter would be created d) charge would not be conserved Homework EquationsThe Attempt at a...

1. Link to problem and the answer I got - https://ibb.co/ncGfDA 2. I got an answer, but I was wondering if this is correct or not? Am I correct to say (in part c) that the vertical component of the hinge's force will be equal to the sum of the vertical forces being exerted in the negative...

Generally speaking, would it be better to pair a CS/Math minor/minor or minor/major (respectively) with physics or an additional natural science major (e.g., biochem, biophysics, chemistry) with physics? I plan on going to grad school to either pursue a physics Ph.D. or a master's in...

On a multi-pair cable where each individual pair has its own isolated shield and there is one overall shield around all of the pairs, why do we ground the overall shield at both ends and the individual shields only at the cable origin. I can't find IEEE 518 right now, but i believe it tells you...

Hi I need help to understand how electric potential could be zero at the center of two equal but opposite charges. It seems, there is a no field free region anywhere inside the space between the charges. If I move a test charge from negative to positive charge or otherwise, there seems to be no...

Homework Statement In a few more months I have to present a report about pair production in quantum electrodynamics, using Feynman diagrams. I have been using the QFT Schwartz book, I find it a bit advanced for my level, could someone recommend me a book to study this phenomenon?. Thank you...

The light source in the DCQE experiment of Kim et al is a laser which illuminates two slits which are immediately followed by an SPDC. The latter is therefore excited coherently in two narrow stripes referred to as "slits". The output has a small amplitude of down-converted entangled pairs. The...

Hi, in determining the temperature of stars using colour index (U-B,B-V,V-R, etc), why do we need to use the appropriate pairs of filters based on their range of temperature? (this is what i read from wiki) For cool stars, we use R-I, and for hotter stars, we use B-V. I don't understand how...

Homework Statement You are presented with a circumstance in which three children are playing on a frozen pond. The three small children of mass 20.00 kg, 24.00 kg, and 16.00 kg, respectively, hold hands, and are pulled across a smooth frozen pond by a larger boy on skates, who pulls a...

In pair production, if the photon has an energy greater than 1.02 MeV, why can't a lower energy photon remain after creation of the electron-positron pair? For example, if you have a 10 MeV photon interacting with a carbon nucleus, why are the stated products of pair production the carbon...