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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81
votes
11answers
11k views

Why must a physical theory be mathematically self-consistent? [closed]

I always read in modern physics textbooks and articles about the need for physical theories to be mathematically self-consistent, which implies that the theories must not produce contradictions or ...
2
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3answers
311 views

What is “normal” about normal frequencies and normal modes in coupled oscillations?

So, my question is what does the "normal" part mean when one talks about normal frequencies and normal modes in coupled oscillations. Does it have to do with the normal coordinates that one uses when ...
1
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1answer
167 views

How are you the special points/critical points in the Brillouin Zone pronounced? [closed]

I know that this isn't exactly physics, but I don't know where to ask. http://en.wikipedia.org/wiki/Brillouin_zone#Cubic_lattice_system_CUB.281.29.2C_BCC.281.29.2C_FCC.281.29 The critical points/...
11
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14answers
8k views

How to pour water from a bottle as fast as possible

When one pours water out of a bottle, it first flows smoothly but then a pressure 'blockage' develops and the pouring becomes interrupted and turbulent, so that the water comes out in splashes. This ...
0
votes
1answer
182 views

Fun to read non-Feynman introductory physics book [duplicate]

I am an almost layman in physics, and don't know much in math (only basic knowledge upto trig ), and want to learn physics . . As I am completely inexperienced, and considering most of ...
0
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0answers
54 views

Causal networks and “local” entanglement

On his Opus Maximus, a new kind of Science, Stephen Wolfram suggests that causal networks can create behaviour similar to entanglement because the local structure of space is only an averaged ...
-4
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2answers
396 views

Soft question - Why do theoretical physics ? and what is its motivation? [closed]

Okay some background - I am a Theoretical physics graduate student (and i would go even further calling myself a math person) and quite recently I have been into this question and am finding it hard ...
0
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1answer
207 views

Notation of integrals

Hi I am relatively new to quantum mechanics. I encountered a certain use of notation which I am curious about, I will provide the context and question now: We have the basis $\{ | \vec{r} \rangle \} ...
-1
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2answers
2k views

Is electromotive force really a force? [duplicate]

As far the definition goes emf of electromotive force is basically potential difference. It even has dimensions of potential. Then why is it called a force?
3
votes
0answers
422 views

How are these modern, sexy physics figures made? [closed]

I am curious to know how the figures in these popular introductory physics textbooks are made. As examples of what I mean, see the posted figures and my comments, all from various editions of Serway ...
3
votes
3answers
5k views

What is beyond Gamma Rays and Radiowaves in the Electromagnetic Spectrum?

The electromagnetic spectrum is commonly refered to as consisting of; Radio-waves, Microwaves, Infrared, Visible Light, Ultraviolet, X-rays, Gamma Rays - of increasing frequency from left to right. ...
1
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1answer
210 views

Quantum teleportation and macroscopic objects

Purely speculative. If not allowed, I'll delete. If quantum teleportation was scalable to macroscopic objects, I assume it would require an amount of matter at the destination, equal to the amount of ...
26
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3answers
2k views

The scope of physics, as taught in modern times

I am asking this question based on my recent experience as a physics major at a well-known school of science and engineering. My basic question is, Why does the field of physics (at least at an ...
0
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1answer
2k views

What is gate symmetry?

I just read this interesting interview with Frank Wilczek and he talks a couple of times about gate symmetry, without ever defining the term. This isn't a term I've come across, and google throws up ...
-1
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1answer
162 views

Sequence of topics for studying quantum theory (Research strategy) [duplicate]

I am trying to learn about the higher level basics of physics. I want to cover up all that is included in particle physics/quantum physics. Now being in high school, I only know partially about ...
2
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0answers
403 views

Self Learning Quantum Mechanics and QFT, how to? [closed]

I've searched the board and several threads were found, but they all were very old and closed. I'm interested in learning and understanding quantum mechanics, after that possibly also QFT. I have ...
0
votes
1answer
109 views

How to consolidate what you've learned? [closed]

I'm reading through two books right now on the topics on quantum mechanics and particle physics. I'd like to know, how does one generally go back and consolidate what they've learned? There are ...
0
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0answers
298 views

Does the analogous saying: “matter is essentially 'condensed' energy” have any merit?

Einstein in his derivation of special relativity came upon the equivalence of energy and matter, and given the right circumstances, the relation can go either way - matter can become energy, and ...
-1
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2answers
214 views

Disproving the mathematical universe hypothesis [closed]

The mathematical universe hypothesis is claimed by Lee Smolin to be falsifiable: [...] it is easy to disprove the mathematical-universe hypothesis. Simply exhibit one property of the natural world ...
0
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2answers
438 views

How are unitary matrices and unitary random matrices associated with physics or quantum mechanics? [closed]

Please forgive my ignorance, my back ground is not physics. I am looking for distance measure between two unitary matrix (for my work). So my starting point is where else unitary matrix is applicable?...
3
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0answers
74 views

Lab equipment - where to start [closed]

I've started to seriously study physics on my own, using various resources such as edX courses etc. However I believe that carrying out experiments will help me gain a deeper understanding of the ...
-1
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2answers
433 views

What causes the expansion of space? [closed]

What is causing space to expand? Is it due to some kind of innate property or is it due to some force? I did a google search on this and found lots of articles explaining that space is expanding ...
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2answers
108 views

Could I create a banana? [closed]

As I understand it, until such time as stars were formed and heavier elements could be created, there was just hydrogen and helium, plus trace amounts of lithium an beryllium. Question: if everything ...
2
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0answers
76 views

How to teach/learn physics - reference request [closed]

I remember reading a paper (or a transcript of a talk) which describes the process of learning/teaching physics as a landing on a planet. In order to find a suitable place to land, you need to orbit ...
1
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1answer
77 views

Note and homework organization [closed]

I am currently in a mechanics class and have some trouble trying to figure out how I should structure my lecture notes and my homework. I recently began rewriting my notes after class but I am still ...
-5
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1answer
95 views

Strange equation on notebook [closed]

It could sound like a silly question, but I found this equation written in my notebook and never knew what was the meaning and who wrote it. I think it could be related to some physics equation, and ...
2
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0answers
111 views

What is the “single equation” in string theory that's an inch long? [duplicate]

Michio Kaku, famous theoretical physicist claims to be one of the founders of string field theory and to have contributed a equation that's "no bigger than your thumb" that ties general relativity and ...
1
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1answer
336 views

$3$ dimensional representation of Electric Field lines between Two particles

I have seen in many books the $2$ dimensional representation of field lines (between two particles having equal positive charge) as- But I am trying to visualise this $3$ dimensionally as how the ...
1
vote
1answer
197 views

Controlling the universe through the “Many-worlds” interpretation [closed]

I was reading upon a comic when I found some interesting content concerning the "Many-worlds" interpretation and how it could be used in quite an extreme manner. Imagine we had a "END" machine. When ...
4
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1answer
552 views

How much QFT do I need to get started on String Theory? [closed]

I want to get started learning String Theory (most likely from David Tong's lecture notes) and I would like to know which topics I need to know from QFT. In particular, if I were to follow Peskin, ...
6
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1answer
181 views

Methodology: how to deal with non-rigorous derivations [closed]

This is a reformulation of https://physics.stackexchange.com/questions/238371/why-are-non-rigorous-derivations-in-classical-mechanics-and-electromagnetism-tau which got closed as off-topic because it ...
3
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0answers
54 views

Direction about future [closed]

I am finishing high school this year and i want to be a theoretical physicist. My academic result in mathematics is not good throughout last 5 years. But physics is my dream. I want to overcome every ...
0
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1answer
310 views

What is the meaning of this Feynman's statement? [closed]

Richard Feynman has a strange statement in first lecture of his known book "Feynman Lectures on Physics. He says If a piece of steel or a piece of salt, consisting of atoms one next to the other, ...
12
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2answers
576 views

Are derivations of physical laws less important than the laws themselves? [closed]

The proportionality between the kinetic energy of gas molecules and temperature is a well-known result. This is usually shown by considering a cubical box containing an ideal gas, and postulating that ...
-1
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1answer
94 views

Where would you go to get feedback, advice and assistance for a new theory of physics? [closed]

I know that crackpots are constantly running down physicists to pitch them on a "new theory" that solves everything. This has understandably led to extreme skepticism for anyone not affiliated with a ...
1
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0answers
73 views

What are some of the best Physics resources online? [duplicate]

Are there any sites similar to (in terms of function and quality) Paul's Online Math Notes, 17Calculus.com, or PatrickJMT.com, for Physics (besides Khan Academy)? I've googled this, but the sites I'...
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2answers
1k views

Can Newton's law of gravitation and Einstein's GR be considered true and complete laws of gravitation? [closed]

Newton's law of gravitation and Einstein's general relativity (GR) are empirical laws of gravitation that are strong on description and prediction but lack deterministic and/or causal rigor, which ...
5
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2answers
379 views

Are ergs commonly used in astrophysics? If so, is there a specific reason for it?

I was reading the recent LIGO paper and one passage stuck out to me: The system reached a peak gravitational-wave luminosity of $3.6^{+0.5}_{−0.4}× 10^{56}\:\mathrm{erg/s}$, equivalent to $200^{+30}...
4
votes
0answers
118 views

Are there any open questions in physics that a layman can analyze? [closed]

In math, there are questions like "What is the minimum number of crosses that this knot has?" which can't fundamentally be solved and simply take a lot of trial and error for an answer. This means ...
7
votes
3answers
3k views

Is it too late to study physics? [closed]

I'm 24 year old student and I study Bachelor's degree of information technology. This is my last year there. Before I applied to this school I didn't know (remember) anything about mathematics or ...
2
votes
1answer
73 views

Do the equations on this piece of art have physical significance

Someone I know owns a piece of art, which is shown in the figure. $$[\varphi_\alpha(x), \varphi_\beta(y)]= -i\Delta_{\alpha\beta}(x-y)$$ and $$U[\sigma,\sigma_0]= I-i\int_{\sigma_0}^\sigma\...
1
vote
4answers
129 views

How to explain to a child why can acceleration be positive or negative? [closed]

I want to find out how can acceleration be negative? I have an answer and this answer is: $$a=\frac{v_f-v_i}{t_f-t_i} < 0$$ because $v_f < v_i$ where $v_f$ is final velocity and $v_i$ is ...
0
votes
2answers
415 views

do Significant Figures apply with numbers without units?

say i need to divide a number with a unit to a number without a unit, e.g.: 16.4 meters / 2 Following the rules on significant figures, will the correct answer be 8.2m (since 2 has no unit), or 8 m (...
2
votes
2answers
558 views

What is the opposite of quantization?

Is the opposite of quantization just taking the limit $h \rightarrow 0$ ? Or are there more steps involved (maybe related to bosons and fermions?)? How would one call the the opposite of quantization? ...
0
votes
1answer
109 views

If you play more than one music track at once on a computer, does the sound heard get louder?

Say you are using a computer and have multiple Youtube videos playing music (or any other video) at the same time, does the sound produced by the computer's speakers (or a pair of headphones) become ...
0
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0answers
66 views

Why is Bohr's explanation called Bohr's model and not Bohr's theory?

I have seen an answer which tells the difference between model (specific) and a theory (general). And it makes sense 'coz Bohr explained it for the hydrogen atom only. But did he not make a set of ...
0
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1answer
91 views

Understanding this metaphor involving e-mails, chaos and phase transitions [closed]

I asked this question on the English Stack Exchange and people advised to try get the answer here. I can’t get the idea of metaphor in the last sentence of the following quote: Instead, email ...
1
vote
1answer
307 views

Will an Electrical Engineering Minor give me a significant advantage in experimental physics? [closed]

I'm currently choosing courses to complete in my university degree (science) and thought completing some basic electrical engineering may be useful if I go into academic experimental physics research. ...
1
vote
1answer
265 views

Why is there empirical evidence in physics more than an analytic evidence? [closed]

In case of mathematics, you can make your own rules and play with them. For example, Euclied made his own rule of Eucledian geometry, and Reiman (or other Non-Eucledian geometers) made their own rule ...