# Tagged Questions

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.

4answers
63 views

### How to explain to a child why can acceleration be positive or negative? [on hold]

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 ...
2answers
35 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 ...
2answers
99 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? ...
1answer
44 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 ...
0answers
22 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 ...
1answer
73 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 ...
1answer
40 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. ...
1answer
72 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 ...
1answer
29 views

### How do we call in English scientific terms the Fermat's principle about back and forth light traversal?

We know that the path followed by the light from point A to point B is independent of the direction of propagation of light. This is what is called in French "le principe de retour inverse de la ...
3answers
2k views

### Can we tell when an established theory is wrong?

I was reading the following answer from this question: In physics, you cannot ask / answer why without ambiguity. Now, we observe that the speed of light is finite and that it seems to be the ...
1answer
59 views

### Dot product and divergence [closed]

Divergence is represented by dot product. How is the divergence related to dot product? And curl is represented by cross product. How is the curl related to cross product?
0answers
43 views

### What type of physicist studies quantum physics the most? [closed]

I want to become a physicist, and I am particularly interested in quantum physics. I know quantum physics has applications in many branches of physics. Condensed matter physicists use it among others. ...
0answers
90 views

### Which scientist is this?

Okay so I was watching discovery channel, in that i saw a man cleaning live electric wires of 10k volts in the air, he was not touching the ground. They said he was able to do this because of the ...
0answers
93 views

### My bathroom door stays open in summer [closed]

My bathroom door remains open in summer, but in the winter it stays about halfway between fully open (90 degree angle, against a window) and closed. The door is between bedroom and bathroom and it is ...
2answers
60 views

### Computational advantages of various notations for electromagnetism [closed]

Most undergraduate electromagnetism classes and textbooks use vector notation to describe Maxwell's equations. However, there are other notations like differential geometry and geometric calculus ...
0answers
21 views

### Classical Mechanics Resources [duplicate]

I hope that my question doesn't violate the posting rules. I was wondering if any of you have any resources (websites, books, etc.) for classical mechanics. My first week of classical mechanics has ...
1answer
86 views

### What defines a physical property? [closed]

The physical world around us has all sorts of properties, shape, color etc. If you move on to more complex systems, there are even more like some emotional properties etc. Why do we deem only ...
0answers
35 views

### How exactly are the relative strengths of gravity and electromagnetism quantified? [duplicate]

I've often heard it said that gravity is much weaker than electromagnetism, and after looking at several questions on SE, I feel that I've got at least a qualitative handle on the concept -- gravity ...
4answers
805 views

### Physics after a Theory of Everything [closed]

There is a lot of controversy over the existence of a Theory of Everything (ToE), and as far as I know, we are a long way from having a possible candidate. But what interests me is, what after that? ...
2answers
100 views

### What are some “I wish someone had parted that wisdom onto me” tips for beginning a bachelor's degree in Physics? [closed]

I start classes next Monday for Physics and I am beyond nervous. I don't really know what to expect in the big world of upper-level science. Granted, I'm only going for an Undergrad right now, but I'm ...
1answer
54 views

### What are some physics books written in dialogue or story form, e.g., a teacher explaining to a student? [closed]

A good example would be How to Teach Quantum Physics to Your Dog by Chad Orzel.
0answers
24 views

### Good book to self learn physics from beginner level [duplicate]

I am looking for a book that is similar to the Gelfand books on Algebra or Trigonometry. These really help the reader understand the material. Any recommendations for a similar book for physics?
0answers
43 views

### Why do many equations need squared powers? [duplicate]

It seems that an equation factor must be “squared” as a convenient approximation to balance out some other series of factors invisibly . Might $E=mc^{1.95}$ work as well as $E=mc^2$? Might ...
0answers
24 views

### Types of research problems [closed]

I got curious about the general types of research problems which one encounters in theoretical and mathematical physics like.... Creating new laws out of data like Dirac or Einstein. Considering a ...
1answer
92 views

### How do hotel peepholes only work in one direction?

Basically the title. Light can go into my room through some lenses so that I can see it, but light can't escape my room so that people outside? The article about peepholes on Wikipedia doesn't ...
1answer
82 views

### Why does the symbol have an arrow? [closed]

What does the arrow in the symbol mean? Does it mean that it is a variable voltmeter and ammeter?
1answer
46 views

### Difference between escape velocity and speed [duplicate]

What is the difference between escape velocity and escape speed , is their any error if we use them interchangeably?
0answers
80 views

### What depth of learning must be achieved to sufficently understand advanced physics topics? [closed]

I was recently asked the following question by a friend of mine who is an undergraduate mathematics student, and I thought it would be beneficial to see what the members here have to say about it, as ...
1answer
52 views

### How can I properly learn relativity with an electrical engineering background? [closed]

I want to properly learn the theory of relativity, purely for self-interest. When I say relativity, I mean both flavours: special and general. Are there any good books which go into both the ...
0answers
35 views

### Frozen water cooler bottle [closed]

My water bottle for my water cooler is frozen. Should I place it onto the water cooler while it is frozen, wait till it thaws a bit, or wait till it thaws completely?
1answer
41 views

### Is there a name for leptons that are not neutrinos?

Is there a name for leptons that are not neutrinos? Not sure if its exists, its not particularly easy to search for. Is there a name for the set of charged leptons (or leptons that are not neutrinos)? ...
0answers
71 views

### Why are so many relationships in physics described by equations? [closed]

Consider $f$, some mapping between two ordered subsets of the natural numbers, $A$ and $B$. I see two ways $f$ can be expressed. The first way is an equation that defines $f$ (i.e. $f(A) = 2A$). ...
2answers
65 views

### What exactly is an arbitrary parameter?

I was reading the article Turning Points: A meeting with Enrico Fermi by Freeman Dyson (available e.g. here), and I had a question about Dyson's use of the term 'arbitrary parameter'. More ...
0answers
59 views

### Why isn't $G=1$ as common as $c=\hbar=1$? [closed]

It is standard practice in theoretical physics to use a system of units in which $c=\hbar=1$. However, even though you could also set $G=1$, most physicists prefer not to. For example, in my cosmology ...
4answers
119 views

### What does “the fabric of space and time” actually mean? [closed]

I've heard the term "the fabric of space and time" in both physics and science fiction, and although I know it has something to do with general relativity, I don't understand what, specifically, ...
1answer
48 views

### Does gravity affects on electrons in a noticeable way? [closed]

Is there a way to force a free electron move in a low speed in order to observe it actually hitting 'on the floor'?
1answer
51 views

### Is there a way to study mechanics without having to rely on free body diagrams?

For example, consider a very simple situation often used as example in teaching: a horse pulling a stone through a rope attaching them. The analysis goes something like this: There is a force ...
1answer
72 views

### Feynman's question on the mathematical machinery underlying nature [duplicate]

Physicist Richard Feynman said in his lectures "It always bothers me that according to the laws as we understand them today, it takes a computing machine an infinite number of logical ...
0answers
28 views

### Approximating Gallons of Gas Needed for Trip (read: physics grad. with too much free time)

My departure from college has left me with an itch for physics-y problems to solve, and my boredom and free time gave way to this approximation of the gallons of gas I use for the trip to my ...
4answers
236 views

### Confusion about the concept of cosmological horizon

This question was inspired by this one By definition we cannot see any event happening beyond the cosmological horizon. Let us assume that the expansion rate of the universe is such that the radius ...
0answers
18 views

### Hiccup in frequency domain

Main question: What would the Fourier transform of hiccup look like? This question is too general so let me elaborate a few possible approaches. Hiccup just as a series of pulses (of no matter what ...
1answer
124 views

### Why do astronomers call all elements heavier than helium “metals”?

I understand that a scientific term need not be constrained by its etymology. But is there some significant reason why astronomers choose to call all elements heavier than helium "metals"? Are ...
2answers
108 views

### Does it make sense for physics to predict the unphysical? [closed]

I hear people say things like "inside a black hole the laws of physics are not valid" or "there can be parallel universes with different physical laws" or "before the big bang there was nothing". ...
0answers
96 views

### Real world applications of post-1950s High Energy Physics [closed]

Imagine a world where people knew everything we know today except for high energy physics, where their knowledge ends at our ~1950s level. Is there any real world application, any particular piece of ...
0answers
45 views

### Sticky physics of pasta mixture [duplicate]

When you mix cooked noodles or other "prevailing 1D pasta" like spaghetti with other ingredients like olives, pieces of meat (not minced) etc. you will probably experience the fact, that the mixture ...
1answer
53 views

### Do physicists subscribe to Occam's razor? If so, how do you define 'all things being equal'? [closed]

The question here is the title: Do physicists subscribe to Occam's razor? If so, how do you define 'all things being equal'?
1answer
46 views

### How Does Rotational and Turbulent Motion Contribute to the Pressures of Dynamical Systems?

Rotational and turbulent motion can deepen a gravity well in a galaxy or galaxy cluster. In an analysis of the mass components of a large body, this would appear to be one of the components. Does it ...
0answers
21 views

### What exactly is wavefield extrapolation?

I am trying to understand what exactly wavefield extrapolation is. I can understand extrapolation of a function, 'wave' and 'field' as well; but could not understand the meaning or the problem ...
1answer
41 views

### Why did the inflation era not produce decompactification of the extra dimensions of string theory?

My question is undoubtedly naive, due to lack of background, but any answers, or simply comments with short explanations of my incorrect assumptions, would be appreciated. I must point out this ...
0answers
24 views

### Book for quantum field theory similar to Ballentine's quantum mechanics book [duplicate]

I have been studying quantum mechanics from Ballentine's book. I enjoy such books. I want somebody here to recommendation a book for qft with similar approach.