Science topics: Physics

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# Physics - Science topic

Physics related research discussions

Questions related to Physics

In my early education I was taught radioactive decay was - in general - not affected by environmental variables. This seems to have been disputed in recent years. I'm curious about the current state of the debate. Are there good reasons to think radioactive decay rates are affected by environmental variables?

A small eccentric motor vibrates on a floor supported by a single rod. Changing the voltage applied to motor the rpm frequency changes. Still why the frequency of whole system remains constant even if system is considered steady state response? I conducted an experiment and found the frequency remains constant for whatever voltage I choose for the motor. Shouldn't the forced frequency be equal to the frequency of oscillation of system. I also changed the rod dimensions but the frequency of system changed but remained constant for whatever voltage I used.

Every metal has its own work function. if several metals are used in multilayer structures such as [Co/Ni] multilayer what will be the effect of the work function of the electrode? Can these multilayer structures change the individual workfunction?

Is is possible to find out if a material can function as a cathode or anode by just looking at cyclic voltammetry.

What is the best way to teach physics? And what methodology could be adopted? Share your opinion or experience so that we can enhance our teaching whether in the classroom or even in the daily life of our social relationships.

Hi,

I am trying to measure resistivity/conductivity across a diamond shaped conductor with small extrusion so this is an irregular shape conductor. I am trying to find the geometrical effect on the shape of conductor.

Resistance = (Resistivity*Length)/Area (1)

This formula works very well for a uniformed section. e.g. a cube of (L=B=H=10 mm )of Copper

my results verifies my analytical calculation.

if I add a small extrusion(L:2mm B:2mm H:2 mm)to a Copper conductor (L:10mm B:10mm H:2 mm) and apply a small voltage through that extrusion.

analytically the Area of cross section should be the area of extrusion.(2X2= 4mm^2)

But the LS Dyna simulation results doesn't match this time with the analytical value.

I have kept all condition same.

Then I tried by taking the entire area of conductor (not just the extrusion) as the area of cross section of (10X2= 20mm^2)

The two sections have different area of cross section therefore current

injection will be spread outward in the section. In series circuit, current is same throughout

and the Voltage is a scalar potential. We impose a voltage at the inlet. Same as case1. For the

Case 1 our Equivalent Resistance was same as the Circuit Resistance. The Change in Geometry

Resistance is calculated using eqn (1) with 2 conductor in series. We have current injected through A1 which

then enters our model through A2. The A2 theoretically is same as A1. However, the results of

the LS dyna show a big margin of error when A1=A2, whereas the results give a good

approximation when the A2 is taken as Equivalent Area with the width of the section taken as

the entire width of 10 mm instead of 2 mm

Analytical and Simulation difference in value of current, due to difference.

I am stuck at this basic problem, Refer to the image for understanding the 2 cases.

help will be appreciated.

Thank you for reading this.

By dynamical systems, I mean systems that can be modeled by ODEs.

For linear ODEs, we can investigate the stability by eigenvalues, and for nonlinear systems as well as linear systems we can use the Lyapunov stability theory.

I want to know is there any other method to investigate the stability of dynamical systems?

What are different coil shapes used in Transcranial Magnetic Stimulation? What are their differences (in induced current)? Do they have different applications?

I am just asking the norms in the academic community where many review papers are being also published as book chapters with very little changes. Is it ethical or not.

As you know, a time crystal shows oscillations with a period

*longer*than the driving force. Is it possible to use this feature in molecular machine synthesis? Does this provide any advantages to molecular machines?The very common experiment in optics to demonstrate that light behaves same as the wave is single-slit diffraction.

If we assume that the thickness of the barriers is 0.1 mm, then the length of a slot along the optical axis will be a long route as a green photon will measure it nearly two hundred times larger than its own size.

Now the question is how the photon behaves along with that long route? Does it behave as a particle or wave? If the exit of the slot or a pinhole is causing photon behaves as a wave then why the entrance wouldn't do that? And if we accept that photon behaves like a wave as it enters the single slit or the pinhole, then formally we should apply the Fresnel diffraction equation from the entry of the slot that will lead us to nowhere.

In my opinion, wave-particle duality is leading us solely to some useful approximation but it doesn't talk about reality, as it cannot explain a sort of experiments that unfortunately have been ignored or left behind such as the glory of the shadow, and also the stretching the shadows when they meet each other and so on.

For sure, wave-particle duality is not the end of science and for sure five hundred years later people will not consider the existence as do we do now the same as us that we don't see the things same as our ancestors, so we should be open-minded to be able to open the new horizons.

As human population expand, our greed too. Growth in electricity network, causing substantially damage to bird’s population, like mostly collision with electricity line. as per my knowledge, there are two ways to prevent death from electricity, like if it is high or medium power voltage lines, then we made underground line, and if it is low voltage line then we do insulation of line, but it is much expensive and laborious. So, is there any other methods or interdisciplinary approach to avoid death of birds?

Mostly medium to large size birds face obstacle during flight like Crane sp, Bustard, peafowl, Flamingo etc

Indeed, I have observed that there is some scientific journals that listed in Scopus sources of not good quality from scientific point of view. At the same time some Universities are depending on Scoups in a similar manner to that of Thomson & Routers or Clarivate analytics.

Was Aristotle actually wrong when he stated: "Objects fall at a speed that is proportional to their weight. In other words, if you took a wooden object and a metal object of the same size and dropped them both, the heavier metal object would fall at a proportionally faster speed ". Or is it that he was smart enough to combine all the physical forces and give a sum up image of what would happen?!!

Currently designing power system for Lunar rover. Solar power and RTG are the planned power sources during sunlit periods however secondary Li-ion batteries will be used to operate in PSR's, these will of course rely on solar power to recharge as the RTG produces only 30We. By calculation the batteries should take around 3-5hrs to recharge however I'm concerned about the power required to do this? Simply, P=IV and so if the 60Ah 28V battery has a 7 amp charge current it would require 196W (7*28). This seems high but I can't seem to justify another method of calculating this??

I also ask for advice on how to distribute the batteries throughout the rover? Fewer large packs with high Ah ratings or smaller packs but more of them?

One day I heard from a Cosmologist professor that we have worlds with several times at the same time( or multi-time )! This subject makes my mind busy these days! I never saw that professor again. Do we have books about this? What is your opinion? What is the difference between a world without the time or a world with multi-time?

I'm currently designing solar panels for a lunar rover MSc project. Two options of the solar panel are being considered, 1) The solar cells are directly mounted to the rover body however the maximum space available is around 0.66m2, constraining power production but less mass of mounting/structure supports 2) A panel made up of solar cells is mounted slightly away from the body but in the same orientation, this would allow for a bigger size however increased mass for the construction of the panel and the mount structure. I'm asking for opinions on how to trade these methods off and the typical masses to expect, currently the bare solar masses is below 1kg for sizes around 1m2 and under. Thanks!

These are all very specific questions related to some lab questions I am supposed to fill out. I was able to do the first part, and know the equation for the Lande factor for the second, but I do not know exactly what the terms are going to be. Secondly, the Doppler question is very confusing to me because the reference material I have does not talk about this at all. Would the equation I want to use be the " full width at half maximum" equation I was able to find on Wikipedia here: https://en.wikipedia.org/wiki/Doppler_broadening? This just seems like the only thing I could find which has terms that I could look up and use from the problem. I have attached the questions for more details on these questions. Thank you.

physic and engineering properties of sub tropic peat because i want to compare with tropical peat

Dear all,

I am trying to compute the theoretical efficiency of a photovoltaic cell using the method described in the attached paper, which is based on the classical Shockley and Queisser arguments (available here: )

Part of the calculation involves the efficiency factor n_rec = V_oc / Vg where V_oc is the open circuit voltage and Vg the bandgap voltage (Equation 13).

As a far as I understand, from a physical standpoint n_rec should be smaller than 1, since V_oc cannot be superior to Vg. Nevertheless, I do obtain n_rec values higher than 1 (i.e. V_oc > Vg), when I consider for instance a blackbody emitter at 6000K, a PV cell temperature = 300K, 100% radiative recombinations (f_rec = 1) and a bandgap of 1 eV.

Therefore, I am wondering: is there something wrong with my calculation ? or does the model have some limitation that I am not aware of ?

From a mathematical standpoint, I don't see what enforces V_OC < Vg, would someone be able to explain this?

Thanks a lot for your help!

Dear Sirs,

I think many knows the ideas due to Jules Henri Poincaré that the physics laws can be formally rewriten as a space-time curvature or as new geometry solely without forces. It is because the physics laws and geometry laws only together are verified in the experiment. So we can arbitrary choose the one of them.

Do you know any works, researchers who realized this idea. I understand that it is just fantasy as it is not proved in the experiment for all forces excepting gravitation.

Do you know works where three Newtons laws are rewritten as just space-time curvature or 5D space curvature or the like without FORCES. Kaluzi-Klein theory is only about electricity.

I am interested in collaborating with any researcher working on modelling corona virus using fractional derivatives. If you are a researcher or you have a related project, please feel free to let me know if you need someone to collaborate with you on this research study. If you know someone else working on this research project, please share my collaboration interest with him.her. I would be very happy to collaborate on this research project with other researchers worldwide.

At the moment, only the lazy one doesn't investigate high-entropy materials. But what is that?

Distribution dominates policy. Resources are injected at a point and distribute across communities. Can the distribution be almost instantaneous as in the heat equation? Do the resources morph and distribute, drawing in the wave equation? Where is stability (cf. Laplace equation)? These seem basic questions of public policy. Yet, the big three rarely feature in scholarship on public policy. Why?

I was thinking of the fact that as far I know as a 2nd-year undergrad student, Economists always state their inference by taking other things constant or Ceteris Paribus. But in real state everything changes, so can we use the law of relativity or the illusion of time concept of physics and apply it to economics? Please do give your opinion. Thank You!

We know that by drawing a magnet close to a closed circular circuit, a current in the circuit is induced. Why? (I don't mean the mathematical description or the law of Faraday's induction, what is the cause of physics? What causes electrons to move?)

In experiments we only deal with hermitian operators and they are called physical observables. But in quantum theory non-hermitian operators also exist. Are we using them only as a mathematical requirement or is there any other reason for their existence?

In physics, we have a number of "fundamental" variables: force, mass, velocity, acceleration, time, position, electric field, spin, charge, etc

How do we know that we have in fact got the most compact set of variables? If we were to examine the physics textbooks of an intelligent alien civilization, could it be they have cleverly set up their system of variables so that they don't need (say) "mass"? Maybe mass is accounted by everything else and is hence redundant? Maybe the aliens have factored mass out of their physics and it is not needed?

Bottom line question: how do we know that each of the physical variables we commonly use are fundamental and not, in fact, redundant?

Has anyone tried to formally prove we have a non-redundant compact set?

Is this even something that is possible to prove? Is it an unprovable question to start with? How do we set about trying to prove it?

In the age of Covid19, is there a basic conflict between science and superstition in the discipline of medical knowledge? Are there some simple, sensible, robust and reasonable ways to distinguish a scientific statement (or fact) from a superstitious statement?

To stay focused, the topic will concentrate on science versus superstition in the scientific discipline of medicine. We will try our very best to stay focused and not stray off track. it is very easy to wander off message and be all over the map. i will try to summarize the key conclusions from time to time.

In the age of the Corona Virus, there are so many statements out there. The statements may not be scientific. But if they are not scientific, are they false? Are they fake? Are they simply statements based on superstition.

What should we do if people believe in statements that are not based on science? Should we be polite and tolerate their beliefs?

As long as people do not harm others, then from society’s point of view, the fact that people hold non-scientific hypotheses is probably benign. However, the trouble starts when the same people act these beliefs, and then cause harm to others. The question arises: what should society do in this case?

Based on the discussion, there are two assumptions and four categories.

Assumption1: Beliefs cannot be justified or unjustified.

Assumption2: hypotheses can be disproven

Scientific hypotheses that are based on justified facts in natural causation. Or scientific hypotheses have not been disproven (I prefer the negative formulation because we may never be able to prove anything but we are unable to disprove it.)

Since science cannot give a definitive answer, there are many competing answers that merit our attention, and we may not be able to select among them.

Non-scientific hypotheses are unjustified facts that may be “proven” in the future with better evidence and facts.

Pseudo-scientific hypotheses: not sure where these fit in?

Superstitions are unjustified beliefs in supernatural causation.

One of the consequences of relativistic physics is the rejection of the well-known concepts of space and time in science, and replacing them with the new concept of Minkowski space-time or simply space-time.

In classical mechanics, the three spatial dimensions in Cartesian coordinates are usually denoted by x, y and z. The dimensional symbol of each is L. Time is represented by

*t*with the dimensional symbol of T.In relativistic physics x, y and z are still intactly used for the three spatial dimensions, but time is replaced by

*ct*. It means its dimension has changed from T to L. Therefore, this new time is yet another spatial dimension. One thus wonders where and what is time in space-time?Probably, due to this awkwardness,

*ct*is not commonly used by physicists as the notion for time after more than a century since its introduction and despite the fact that it applies to any object at any speed.The root of this manipulation of time comes directly from Lorentz transformations equations. But what are the consequences of this change?

We are told that an observer in any inertial reference frame is allowed to consider its own frame to be stationary. However, the space-time concept tells us that if the same observer does not move at all in the same frame, he or she still moves at the new so-called time dimension with the speed of light! In fact, every object which is apparently moving at a constant speed through space is actually moving with the speed of light in space-time, divided partially in time and partially in spatial directions. The difference is that going at the speed of light in the time direction is disassociated with momentum energy but going at the fraction of that speed in the other three dimensions accumulates substantial momentum energy, reaching infinity when approaching the speed of light.

Hi,

I'm attempting to create nonlinear metamaterial structures in comsol and I don't know how to measure second harmonic generation.

How do I measure that frequency x goes into structure and generates frequency 2x ?

Thanks for any help.

Einstein, based on his argument in section 6 of 1905 paper, claimed:

“If a unit electric point charge is in motion in an electromagnetic field, the force acting upon it is

**equal**to the electric force which is present at the locality of the charge, and which we ascertain by transformation of the field to a system of co-ordinates at rest relatively to the electrical charge.”Simply, total electromagnetic forces, acting on a moving charge, claimed to be equal calculated in any inertial reference frame; F’ = F.

Using an example, Feynman, in his lectures, failed to prove that electromagnetic forces are equal if calculated in the two inertial frames suggested by Einstein.

His result was F’ =

*γ*FWhy did Feynman fail? Can you find an example to support Einstein’s claim?

Attached file presents and reviews Feynman’s analysis and calculation.

All metaphors are false. But, on restricting this discussion to natural sciences, we hope to use a particular metaphor to clarify important areas in physics and often in dispute by researchers -- also in other areas, including those not a natural science.

The metaphor is that, all one can do in natural sciences is to be a "customer service rep" for someone else's product -- nature.

For example, I did not invent it, and works for billions of years, without halting. I am just the front-end of nature's message, the customer service rep. One can always ask questions and consult the manual, the universe, in case of doubts.

Of course, natural scientists are much more. Some view that our task is to find in all the relative data from phenomena (which is all physics is limited to measure), the absolute, the universally valid, the invariant, that is hidden in them, as Max Planck said first.

But the metaphor above can be useful, especially in other areas, including those not a natural science.

Some "disgruntled customers" (DC), familiar to any well-intentioned customer service rep, remain disgruntled, even when explained that it is not a bug, such that the speed of light is constant to all inertial observers in vacuo, it is a feature of the universe. A feature, not a bug.

When a DC understands, the average DC does not say "thank you", it should be a selfless customer service, good for the soul.

There is also a tendency for a DC to all but hide in silence until all his false answers (in nature, which is the arbiter of falsehoods) are diluted. By RG, or hidden in life. Then, he likely goes back and says it is a new feature, the old bug, that he just invented, and is just "spreading around".

Or, a DC can also repeat a fallacious interpretation, say we never measured it otherwise but locally. Natural science can explain that the Earth moves, the Sun moves, across the galaxy, we launch transmitters beyond the Solar system, and we can see and measure electromagnetism, light, billions of years away, across many galaxies. Then, what is a DC to do?

The average DC understands, but there is always the probability that a DC will name another fallacious argument, ad infinitum if life would physically allow, to deny what could be simply explained, it is not a bug, the DC bug -- it is a supposed feature.

It is a good customer service of someone else's product, though, because there is, actually, no DC. The concept of a DC is a mirage, itself a bug.

Everyone counts, DC or not, in the school called life, and even non-cooperation clarifies, inspires selflessness, is cooperation. Everyone cooperates.

Cooperation is a collective effect, producing unexpected efects.

Even those who try their mortal hand and time in life to be contrarian, a DC, just like Humpty-Dumpty, using nursery rhymes as a scholarly principle, trying strategies to get points at RG, get into a cabal to dialogue and create hits in search.

All is a legitimate, defensible, good use of their limited time, in the school of life, even as if, so may seem to them, that there is no future to account for, to earn.

So, a good customer service should handle all cases, sometimes with silence -- The trust that all is fine, there is no disaster in the whole universe, no wars but progress, it is an open-ended universe in harmony with laws we ignore, but feel more and more in the few laws we already know, and find out.

Nature is in no danger by humans. Everything is already solved, we just have to find it.

To help, Nature has many good customer service reps, in what should be done as a selfless customer service, a good task for the soul. And anyone can always ask questions and consult the manual, the universe, in case of doubts.

The invisible hand was a vivid metaphor for how the market works. No more, no less. It was an attractive metaphor. It was simple and perhaps simplistic. However, people are reading too much into this metaphor, and the misunderstanding has created tremendous confusion.

My question is Can we attain 50-60 Hz Sound frequency on flowing water through tubes? while in background pump is working or other sounds are there (no noise cancellation).

What happens if we have high crossflow velocity of the water lets say 2 to 3 m/s.

Dear Sirs,

Everybody knows plane and spherical wave solutions of Maxwell equations, e.g for decaying plane wave E=E0*exp(-kx)*cos(w(t-x/v)). But seems to me they give the unreal situation that the wave amplitude is nonzero at different points of space at given time moment. Could you advise the experiment or natural phenomenon which produces such a wave in nature?

Maybe we have infinte speed of the EM interaction? Do you know any real solution of Maxwel equations which exists only in one space point at the given time moment? Maybe using delta function? Or maybe there is my mistake?

Is there any matematerial which can reflect right handed circular polarization into Left handed circular polarization or vice versa of the EM waves operating in ultra-wide band?

What does it actually mean to exist? How is it different from non-existence? How can we be sure if something exists or does not exist? I have made a case that these questions are more fundamental than the usually dubbed first question "Why is there something rather than nothing"? Here is a ready link for which I would appreciate your comments.

Please do feel free to share the link with your colleagues and friends who you think might be interested in this topic.

Hello, fellow researchers, I'm looking for the drivers for a plasma diagnostics instrument. PlasCalc 2000, Originally from Mikropack GmbH , later sold to Ocean Optics, now Ocean Inside. We lost the software disk, contacted Ocean Inside and they told us that the instrument is obsolete and no longer provide software/service. I appreciate your help.

Thanks.

Dear all. The

**Normal distribution**(or Gaussian) is mostly used in statistics, natural science and engineering. Their importance is linked with the**Central Limit Theorem**. Is there any ideas how to predict the numbers and parameters of thos Gaussians ? Or any efficient deterministic tool to decompose Gaussian to a finite sum of**Gaussian basic functions**with parameter estimations ? Thank you in advance.Please don't answer because U(T,V) don't have S entropy as argument!!!!!!

May I ask a question on thermodynamic? We know that U(V,T) (caloric eq. of state) and S(P,V) (thermodynamic eq of state) can both be derived from thermodynamic potentials (U F G H) and the fundamental relations. However, U(V,T) doesn't hold full thermodynamic info of the system as U(S,V) does, yet S(P,V) also holds full thermodynamic info of the system.

In which step in derivation to get U(T,V) from U(S,V) lost the thermodynamic info? (the derivation is briefly：1. derive U=TdS+ PdV on V, 2. replace the derivative using Maxwell eq. and 3. finally substitute ideal gas eq or van der waal eq)

Why the similar derivation to get S(P,V) retain full thermodynamic info?

Even if we only have U(T,V), can't we get P using ideal gas eq, then calculate the S by designing reversible processes from (P0,V0,T0) to (P',V',T')? If we can still get S, why U(T,V) doesn't have full thermodynamic info?

The Riemann zeta function or Euler–Riemann zeta hypothesis is the more challenging and unsolved problem in mathematics. What's the applications in physics and science engineering ? Some research advances to solve it ?

Angular shape not spherical

Or

Other than spherical geometry.

Movement in musical scores does not have an equation of motion or a calculus of variations.

Is there any other kind of harmonic motion that does not obey Newtonian law?

Of course, frequency is velocity-like but I do not see this in the literature.

I understand that the force field may be uniform so dF = 0, but is it not true there must be a force if movement occurs.

Some petroleum and geophysics companies use controlled-source seismology for Mineral Inspection and cavity detection. These methods based on impulsive source controllers such as (dynamite, air gun seismic source, etc.). More efficient techniques use a Seismic vibrator for seismic wave generator such as chirp, sine or square seismic waves.

I wonder if recents detections of Gravitational Waves coming from earth or space using optical interferometry, and how to distinguish between each of them, especially when seismic wave have a same chirp form such as Gravitational Waves?

Example of Seismic Source: http://seismicsource.com/html/index.php

Economics struggles with rigour. Development struggles with prejudicial questions. So, why don't we teach our young people social physics? Look at social space as a phenomenon of physics. Deeper economics tried that. But that attempt seems to have ended with Paul Samuelson and his lot. Why? Anyway, it is time for the more complex emerging economies to teach social physics instead of development economics.

In the literature, fractal derivatives provide many physical insights and geometrical interpretations, but I am wondering where we can apply this particular derivative appropriately. Please refer me to references or examples because I am very interested to learn more about new derivatives and their applications!! I greatly appreciate all the brilliant efforts in this discussion!!

If global warming cannot be resolved by controlling/minimising gas emissions, then extraordinary measures may be the only viable options, one of such ideas is placing a solar shield between the sun and earth at the L1 lagrangian point to obtain a reduction in solar insolation . It may sound crazy, more like science fiction to know that a disk of 2000km in diameter would be necessary to reduce solar radiation reaching earth by 1.7%. I wonder about the sort of stresses that would be experienced by such an enormous body. Also, what sort of materials' properties would be required to withstand the conditions at L1, for example solar radiation, other rays. While it is possible to calculate the disk's orbital velocity around the sun, its angular velocity (around its axis) is difficult to calculate. I would be grateful if those with relevant experience could share their thoughts about how such calculations could be achieved.

Hi there

what is the formula of magnetic field force applying on Ferromagnetic material?

can we use the formula of magnetic field applying on magnetic dipoles force to calculate the magnetic field force applying on Ferromagnetic material?

There are many existing publishers that publish high quality books in mathematics, but my question here is: I want some suggestions about publishers who most likely publish books in the field of fractional calculus and fractional differential equations because I am interested in submitting a book proposal for a suggested publisher. Could you please share you information/knowledge about such recommended publishers in this specific field of research in mathematics? I would greatly appreciate your brilliant efforts and time!!

I need steps for measuring the Fatigue endurance and retention of polarization. I soft. There is no option for these measurement. They have other option like P-E loop, hysteresis, I-V, leakage etc.

We have a solution with an oxygen concentration of 6.5 ppm. How to Calculate Oxygen Pressure in a Solution Using Oxygen Concentration?

I am trying to couple light from Laser with M^2=1, wavelength = 1030nm and beam diameter = 1.3mm. Please suggest a lens for efficient coupling into PCF (say 2um core). As far as I know, I have two options, either to use Aspheric lens or Microscope objective, however, I am not really sure which one would be a best choice. As I understood (Please advice if right or wrong)

For efficient coupling, these points should be considered.

1) N.A of lens should be equal or close to that of fibre (PCF)

2) Lens focus diameter should be equal to core size of the fibre (PCF)

3) Input beam should be parallel to Optical axis (Collimated)

Please advice.

Thanks

Are there any good comprehensive review article on qubits? As in, one that gives a whole summary of all the possible platform and compare their strengths and weaknesses, like trapped ion, superconducting qubits, nuclear spin, quantum dots,etc.

Hello everyone,

I was just wondering what is the conception of an infinite ground plane when it comes to the metamaterials. For example, there are times that you need to use an infinite ground plane and I want to know how it affects the metamaterials' properties at the atomic level or how the electrons interact in the Physics point of view??

Or maybe, what are the interactions between E-fields and H-fields inside the structure??

Any answer would be a huge help...

Tnx

In the theory of relativity the upper bound of velocity is included by using the Lorentz transformation. Therefore the theory of relativity can give no answer to my why question. However, in my preprint I explain why:

Preprint On the upper bound of velocity

In theoretical electrical engineering you learn that the group velocity of electromagnetic waves in wave guides can not exceed c. The reason is the electromagnetic properties of empty space and the group velocity of electromagnetic waves. This is derived without needing the Lorentz transformation.

how to spliced different different core size (MFD) fibres ( single mode to graded index multimode). I am trying to splice SMF to GIMF, to fabricate SMF-GIMF-SMF saturable absorber.

Although, I could splice with apparently no power loss (shows 0dB loss). However, splicer shows "Bubble Error", even after several attempts.

note:Please have a look at the photos attached

Thanks

I am manipulating water vapor data obtained by radiosondeo, according to the manual these are given in units of water vapor mixture ratio (g / kg) but in the article I use this data are used in g / cm **2. I am a beginner in the subject of atmospheric chemistry and do not handle this type of units much.

Hi there,

my question concerns a situation in which the law of free fall and the relativity of simultaneity come into play simultaneously.

The general assumptions are as follows:

1. if we let two objects fall at the same time, they will reach the surface at the same time, regardless of their mass (although gravity has a stronger effect on larger masses, inertia is also greater to the same extent).

2. the relativity of simultaneity shows impressively that different observers moving relatively to each other do not have to agree on whether two events really happen at the same time, depending on their reference system.

My question now is, what happens, if we combine both things. A person is standing in a space ship and lets two objects with different masses fall simultaneously through a technical apparatus (atomic clock). In his frame of reference this person has no problem - he sees that both objects arrive at the floor at the same time.
But what does an external observer see when the space ship passes? Does he now have the impression that the objects no longer fall onto the surface at the same time, even though the law of free fall implies uniform acceleration? Or must all external observers agree that both objects reach the floor at the same time, because the law of free fall cannot be circumvented? Or is it the case that the external observer could observe that the person in the space ship does not drop the objects at the same time, although the person in the space ship observes that the objects are dropped at the same time?

As the explanation goes, hole is

*a figment*to the absence of electron as it moves to some different energy state as a result of absorption of energy of some kind. That is, I think of holes as*voids,*which are "*have positive charge for the sake of charge neutrality because there once happened to be an electron at that place. But, it doesn't have it's own actual charge like any other physical charged particle (like an electron), right? Then, how can we define an exciton that is based on coulombic forces between an electron (in conduction band) and a hole (valence band), which actually requires presence of***said to"****two physical charges**?Mass attracts and Energy spreads,

Both Matter and Energy is essentially one and the same thing interchangeably but still it differs in this respect that Energy spreads,

Sir Isaac Newton in his book (Principia Mathematica), stated that it is the property of matter to attract and hence gravitational force is the force of attraction.

Can I say in this regard that Energy is responsible for the force of gravity?,

Since Energy following the second law of thermodynamics and moving from higher state to lower state is in motion as it spreads outward and by Newton's laws of Motion:

The movement(referring Newton's first law) is due to a force outwards, possibly due to the second law of thermodynamics,

Then by Newton's third law, there must be a force equal and opposite that contracts.

This might also explain why matter which is in the form of energy does not spread out completely (being interchanged into energy all at once) and hence remains compressed,

Then is it true that Gravitational Force is the opposing force that balances the force of entropy..., Which is but the property of energy.

So can one say that gravitational force is the result of spread of Energy?

Let us consider two boxes of different energies that are separated by a barrier and box 1 is filled with many electrons. The barrier allows the electrons to tunnel from box 1 to the other side with a 1% probability. In the event that an electron in a given time frame does tunnel through the barrier, does this affect the probability that a different electron teleports through the barrier during the same time frame, or is this probability statistically independent? Therefore in the extreme case, do we know if the probability of ALL electrons tunneling is equal to P(1 electron tunneling)^(Number of electrons). Let us assume that the change in energy due to electrons filling/leaving certain energy levels is negligible.

One remembers, first, that all matter used in anything is constructed of atoms, where atoms are made of particles, where quantum mechanics (QM) physically works.

Any physics, chemistry, engineering, computer science, even mathematics -- where the electrons, light, wave, and number behaviors are determining these fields by Nature -- will

**obey quantum rules**, such as NO "law of the excluded middle" and NO "axiom of choice", and where QM principles play main roles.One reads, for example, at Stanford U. that:

*the concepts and techniques of quantum mechanics are essential in many areas of engineering and science such as materials science, nanotechnology, electronic devices, and photonics.*Nominations by participants here (in order of appearance) include:

**Superfluidity, superconductivity, HVDC with QM rectification by a thyristor (semiconductor), incandescence, laser, quantum decoherence, entanglement, P-type or N-type semiconductors, transistor radio, and the entire known universe for 13.8 billion years so far.**

What is your reasoned opinion? What is your best example of QM having visible effects on microscopic and macroscopic scales?

Lazare Carnot, the father of Sadi Carnot who laid the foundations of thermodynamics with his 1824 monograph on the motive power of heat, authored the 1786 Essai sur les machines en général. Since Sadi Carnot is said to have used some of his father's ideas in his 1824 monograph, for historical reasons (at least) it would be interesting to read the 1824 monograph in view of the 1786 essai. Hence the question: is there an English translation? If so, where?

The 1786 work can be found online at the BnF: Bibliothèque nationale de France.

Hey all

Technical papers or not

Is there one search engine that embraces all the detailed procedures and guidlines for lab scale processes and synthesis methods

As the "distribution lecturer" from the once cult film "Carnival Night" said: "Is there life on Mars, is there life on Mars - this is unknown to science." 66 years ago, when the Eldar Ryazanov took off his famous tape, any other answer would not give a synod academics. And what does today's science say, and not only about the Red Planet? If you ask the question a bit, are there other residences of life in the Universe?

Please explain to me step by step method to calculate the

**Electron Density**of a*Low-Temperature***using***Argon DC Glow Discharge Plasma***Optical Emission Spectroscopy**.This laboratory plasma is produced by

**DC Glow Discharge**of(i) Argon gas

or

(ii) Some other gas mixed with Argon gas

The applied voltage ranges from 300 - 500 volt, whereas the pressure ranges from 0.10 - 0.20 millibar.

I expect my Electron Temperature and Electron Density to be approximate of the order of1 eV and 10^14 - 10^15 per meter cube, respectively.

While I am looking for academic positions in Canada, they are constantly asking for a research proposal in NSERC format. I never had an experience of making a proposal in that format.

Hence, I am requesting the research community here in to share their proposals. If you want to share with me only, please send it as a message. I will keep it confidential.

Any sample of proposal (awarded/non-awarded) in that format will be great help for me to fasten up and amend my proposal. I am very much grateful if someone can share their sample proposals.

Journal, Magazines and Letters publish scientific articles. What is technical difference between these articles and their recognition?

Writing Style, technical soundness, number of words etc.