Questions tagged [soft-question]

Questions that ask about some aspect of physics research or study which doesn't involve the actual physics. In general, soft questions can be answered without using physical reasoning.

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Columbic vs. coulombic efficiency : Is it a pun? [closed]

I just read a paper which seemed to completely unironically use the term "columbic efficiency" instead of "coulombic efficiency". I said "Well that must be a typo/autocorrect&...
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Probability in the Multiverse Interpretation of Quantum Mechanics [duplicate]

The Multiverse Interpretation of Quantum Mechanics interprets a quantum decision as different universes, each with each outcome. I was wondering how probability plays into this. For example, if we ...
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1 vote
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Couldn't understand an example used in explaining fundamental and derived quantities

In my book under topic of fundamental and derived quantities, there is an example which is supposed to explain this concept and it goes like this, As a simple example, if a unit of length is defined, ...
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3 votes
1 answer
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What is this dynamics book that has questions and it's solutions?

I found these questions online and was amazed by how organized this book was so it would be really helpful to know it's name
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When or why to use the $\equiv$ symbol in place of the $=$ symbol?

In literature, I read the following: A typical relationship*, often appearing in the literature, is: $$|-\nabla(\bar p+\rho g z)|\equiv \rho g J=q(\mu w+\rho Bq^m)$$ The nomenclature does not define ...
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Uncertainty principle in deformation quantization

Deformation quantization procedure is a well-known way to quantize a classical phase space (at least formally for Poisson manifolds which is known as formal deformation quantization). Although it is a ...
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How to make sure that I got the solution to a problem correctly?

I'm a physicst autodidact and I've always relied on solution manuals up till now. There are however a lot of great books with no solution manuals that I'd like to study. What should I do? How do I ...
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Problem Solving Books in Physics

I am looking for a book like Paul Zeitz' "Art and Craft of Problem Solving", but applied to physics. Essentially something which simultaneously has both problem solving strategies and ...
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Even at an elementary level, can "force" be defined as "cause of motion"?

In Leçons de physique (Lessons On Physics) (auth. Perez, De Boeck editor) can be found this informal definition of force: "forces are what cause motion". Is this definition accurate? What I ...
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11 votes
2 answers
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If a measurement has 5% error, can we say it has 95% accuracy?

Most often when, in a numerical problem, it is demanded that we calculate the accuracy of the final result, we write the final result in terms of the error. So I want to know if, in a measurement, ...
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Collection of Roger Penrose's scientific drawings [closed]

Being fascinated by the scientific illustrations by Roger Penrose, I am searching for a more comprehensive collection of them. Preferably with concise captions explaining the context and principle of ...
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Do analytical results always "trump" numerical ones? [closed]

Suppose I have a system that can be described by some differential equation(s). If I can manage to write down a proper analytical solution to it, but which I can't quite replicate numerically, whether ...
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Utility of Topological Data Analysis in Theoretical Physics

I audited a lecture on Topological Data Analysis, and I found it really interesting, primarily because of the connection to algebraic topology. I asked the professor if there are any connections to (...
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What branches of electromagnetics (or its interdisciplinary applications) do not require knowledge of electronics for research?

I am extremely interested in electromagnetics and would like to pursue research and later on some job in the field. However, I never found any appeal in electronics, especially since it was introduced ...
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4 votes
2 answers
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How can one generally prevent silly mistakes in very long physics calculations? [closed]

I am a student working on certain open-ended research problems in quantum systems that mostly have long calculations and deal with a large number of terms. I tend to make a lot of silly mistakes ...
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Are there any best websites for physics problems to enhance problem solving skills? [duplicate]

I actually prepare for International physics olymiad. Can anyone please tell me what are the best websites for physics problems (like codeforces, hackerrank, codechef)?
2 votes
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How were old-style Feynman diagrams drawn before software? [closed]

I wasn't sure where to put this question as it's not directly about physics, but before software to draw them was around how were Feynman diagrams drawn in papers? For example ones that look like,
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2 votes
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What research in theoretical physics could a high school student do? [closed]

I already know what I want to conduct my research on (topic: magnetic monopoles), the problem is just that I don't know what to investigate or analyze. What are some research methods you would ...
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How much depth of mathematical understanding do you need to understand (theoretical) physics well at graduate level? [duplicate]

How much depth of mathematical understanding do you need to understand (theoretical) physics well at the level of graduate texts in E&M, relativity, quantum mechanics, quantum field theory etc? I ...
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1 vote
2 answers
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What is a "fundamental law of nature"? [duplicate]

The trigger for this question is from "University Physics with Modern Physics" (by Young & Freedman) when they mentioned that Ohm's law is not actually a law; this sentiment was echoed ...
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Is Gibbs/Boltzmann probability the 'true' probability of a particle being in a particular state in the canonical ensemble

Based on the classical interpretation of probability, the probability for a single particle to be in the $i$th energy state, in an $N$ particle system, should be given by the number of particles in ...
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Question about time dilation and what an observer sees

This is a soft question I was discussing with a friend. Suppose a portal opens up (I know this is fiction) but for the sake of argument, let's suppose something like that happens. And the observer can ...
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Physical meaning of iterated commutators (soft question)

I observed an identity in associative algebra: for $x_1,x_2,x_3$ associative words and $w_1,w_2,w_3$ scalars the following is true \begin{equation} \begin{split} (w_1+w_2+w_3)\;x_1x_2x_3\equiv&\; ...
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1 vote
1 answer
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Brachistochrone Problem without Trigonometric Substitution

I'm trying to numerically reproduce the cycloid solution for the brachistochrone problem. In doing so, I eventually ended up with the following integral: $$ x = \int{\sqrt{\frac{y}{2a-y}} dy} $$ ...
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Criteria for breaking

Consider a system with $1$ degree of freedom. Suppose $2$ particles, each of mass $1$ are placed next to each other. The 1st particle is being acted upon by a $100\text{ N}$ force. In general the ...
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1 vote
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Websites on knowledge of physics [closed]

Here http://mathonline.wikidot.com/ you can see a great website where some mathematical knowledge is organized, and I am wondering if there is a similar website for physics.
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Does inertia imply that a cyclindrical mass in frictionless motion on a horizontal plane keeps moving forever ( with $\vec F = O$)?

Suppose I have a perfectly cylindrical pencil and set it in motion on a perfectly smooth and horizontal table, in such a way that the axis of the pencil is in translation. Is the state of this object ,...
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What is the meaning of the eigenvalues in a damped system?

I am studying the eigenvalues of a an $n\times n$ damped system, such that I get a quadratic eigenvalue problem in the following form: $$\text{det}(\lambda^2\mathbf M + \lambda\mathbf C + \mathbf K)=\...
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What if the radioactive atom in schrodinger's cat was quantum entangled with another radioactive atom

What if the radioactive atom in schroedinger's cat was quantum entangled with another radioactive atom? If we measured the other atom as 'not decayed' from 1000 miles away, then the atom in the box ...
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1 vote
2 answers
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Is there any level of physics that is "solved"? [closed]

At each level of physics, between rotating galaxies, orbiting planets, wind and motion of matter, to motion of molecules, atoms, particles, and maybe strings, there's always some degree of uncertainty ...
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If traveling with relativistic speeds can observer find space denser than normal?

I know that outer space contains few particles per cubic meter, but I am curious if travelling that fast for our brave traveller all of these particles will look like a dense pool of molecules. And ...
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Is this a mistake in a Stanford Encyclopedia article on Quantum Mechanics?

In the SEP's article dealing with Quantum Mechanics , I read this ( Section 2.1, " Vectors and Vector Spaces") https://plato.stanford.edu/entries/qm/: $|A⟩$ and $|B⟩$ are mutually ...
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1 vote
1 answer
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Distinguishing between different types of elliptical polarization

How to distinguish between a mixture of plane polarized and unpolarized light, and a mixture of elliptically polarized and unpolarized light? When we pass plane polarized wave though quarter wave ...
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5 votes
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Will a bullet penetrate farther through 1,000 sheets of paper with no space between the sheets, or with space between them?

Consider a gun pointed at (normal to) a 1,000-page stack of paper. Which would a bullet penetrate farther into in terms of number of pages: the stack as-is, or the same 1,000 pages stacked with spaces ...
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2 votes
2 answers
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Why is string theory considered the best candidate for quantum gravity if it cannot resolve singularities? [closed]

The reason we want a theory of quantum gravity is to be able to understand singularities like the big bang and black holes. However the best candidate so far for such a theory, string theory, does not ...
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3 answers
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Context based teaching pedagogy in physics [closed]

Apologies if this is not the place for such type of questions, please suggest the related community. Q1) Why most of the college physics textbooks are descriptive in nature, like they give the ...
2 votes
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Equilibrium and the derivative of potential energy

In his Classical Mechanics popular lectures ( Lecture 3, at the beginning) , Susskind illustrates the idea of a stationary quantity using an example involving the notion of equilibrium. Link : https:/...
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2 answers
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Understanding Time Dilation in Special Relativity

The equation commonly taught to deal with Time Dilation is $$t'=\gamma t=\frac{1}{\sqrt{1-v^2/c^2}}t$$ where $t$ is the time measured by the observer $A$ at rest (stationary frame of reference), and $...
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4 votes
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When does the interference pattern of DSE disappear as size of "projectile" is increased? [closed]

In trying to learn about Quantum mechanics (QM) from popular science books and Stack Exchange (I of course expect my knowledge to be anything but complete) I regularly come up with seemingly childish ...
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-3 votes
2 answers
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Why do authors write mathematical expressions in their books? [closed]

I'm currently interested in and new to QM and I'm reading a book, that teaches QM in an easy way. But there are many mathematical expressions about various things, like the quantum state of a spin ...
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Does photoelectric effect play a part in the rotation of Crookes radiometer

In this video, a person puts low frequency light in front of a Crookes radiometer, and the vanes don't spin. But they do when he puts a high frequency one. He then later makes some weird claims and ...
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What are applications of the karcher mean in physics?

Given a complete Riemannian manifold $M$, and $x_1,...,x_N \in M$, a karcher mean is defined to be a point $\bar{x}$ that globally minimizes $\frac{1}{N}\sum_{j=1}^Nd_g(x,x_i)$, where $d_g(.,.)$ is ...
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2 votes
2 answers
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Is "Particle Phenomenology" done by Particle Theorists or Particle Experimentalists?

I came across the term "Particle Phenomenology", which is "the application of theoretical physics to experimental data by making quantitative predictions based upon known theories" ...
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Switching from Research in Experimental Particle Physics to Theoretical Particle Physics [duplicate]

It is quite common for physicists to change research areas in the middle of their careers. However, given that currently there's a big difference between experimental particle physics and theoretical ...
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-1 votes
1 answer
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Why do I keep forgetting the physics I've learned? [closed]

I've taken quite a few physics classes over the years and I read about physics when I can. However, I always forget what I've learned. When someone talks about a concept, until I go review briefly ...
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1 vote
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Switching to Theoretical Particle Physics as an Experimental Particle Physicist [closed]

It is quite common for physicists to change research areas in the middle of their careers. However, given that currently there's a big difference between experimental particle physics and theoretical ...
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1 vote
0 answers
90 views

Why has String theory gained so much ground among physicists given that there is no evidence that it is correct? [duplicate]

First I must say that I am not an expert in string theory so my understanding is minimal and therefore feel free to correct any misunderstandings I may have. String theory is very popular among ...
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1 vote
7 answers
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When Sean Carroll says "The Laws Underlying The Physics of Everyday Life Are Completely Understood" , is he being click-baity or is he correct? [closed]

I read three posts of his on his blog: The Laws Underlying The Physics of Everyday Life Are Completely Understood Seriously, The Laws Underlying The Physics of Everyday Life Really Are Completely ...
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2 votes
3 answers
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Name of a class of mechanical systems similar to the $n$-body problem

I am wondering if there is a particular name for the class of mechanical systems defined by "$n$ copies of the same system linked together". I know this is not completely clear, however, my ...
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4 votes
1 answer
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The basic ontology of Statistical Mechanics [closed]

Motivated by the question ("Ontology of QFT", the accepted answer is the perfect example of how ontology questions can be answered and I strongly encourage to read that answer if one is ...
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