DO NOT USE THIS TAG if a more descriptive tag applies.
-5
votes
0answers
65 views
Isn't Experience of Nature important for General Theory Of Physics? [duplicate]
Every law of Physics that we have, is there because it has been experienced by us. Based on our direct experience with the forces of Nature, people used their intellect and gave a mathematical model ...
2
votes
1answer
196 views
Do quantum computers manufactured by D-Wave Systems, Inc. work? [duplicate]
D-wave claims to have built 128 qbit quantum computers which are commercially available?
What I don't understand is that have they really been able to do this given that the scientific community is ...
1
vote
1answer
50 views
recommendation for a physics history/non-fiction book [closed]
I know that there are a lot theses being published on lives of physicists. Is there a history/non-fiction book that tracks the development of a problem chronologically? Like pieces of a puzzle.
I ...
1
vote
1answer
69 views
Power radiated by the sun at different locations
I am wondering can someone help to solve second part which extends first part;
The power radiated by the sun is ${3.9*10^{26}}_{watt}$. The earth orbits the sun in a nearly circular orbit of radius ...
1
vote
2answers
184 views
The meaning of 'postulate' in physics?
What does postulate mean in physics? What is its role in physical theories?
Is it possible to break physical postulates?
0
votes
2answers
206 views
How to teach myself physics needed at undergraduate electrical engineer level? [closed]
I want to learn electrical engineering on my own, specifically because I'm interested in loudspeaker design, more specifically how to design active dipole loudspeakers using DSP crossovers.
I have ...
2
votes
0answers
121 views
What are the biggest unanswered questions in physics today? [closed]
Are there fundamental big questions in physics that most scientists encounter no matter what they're working on, or are most questions details of smaller subtopics? What are the great unknowns of our ...
1
vote
1answer
83 views
Electric Flux Contradiction
I am currently reading about electric flux; and from this passage I am reading, I am sensing a bit of a contradiction:
"If the E-field is not perpendicular to the surface area, then the flux will be ...
3
votes
1answer
258 views
Why does the monitor make a cracking noise?
After switching off the monitor, there's a single crack after a while. I wonder where exactly it comes from.
I know that this is normal and not an indicator of being defect. This sound is also not ...
6
votes
5answers
429 views
Is physics rigorous in the mathematical sense?
I am a student studying Mathematics with no prior knowledge of Physics whatsoever except for very simple equations. I would like to ask, due to my experience with Mathematics:
Is there a set of ...
1
vote
0answers
83 views
Scales and Hooke's Law
Bob weighs $B$ kg and when he steps on a scale, the spring inside gets compressed by $c$ meters. Assuming the scale obeys Hooke's Law, if Alice weights $A$ kg, how much work is done compressing the ...
1
vote
1answer
91 views
Retarded field interaction
I was doing the following thought experiment: imagine a particle that moves at a certain velocity. Imagine also that the particle generates a field that propagates at velocity $v_f$. Well, if the ...
-1
votes
1answer
153 views
Percentage of water that is void or empty space?
At the atomic level, at sea level on earth, what percentage of normal pure drinking water is void or empty space? What percentage of lead (the kind used to insulate from nuclear radiation) is void or ...
1
vote
3answers
263 views
when an object moves downward, is its height negative?
the question is:
A ball is thrown directly downward with an initial speed of 8.00m/s from a height of 30.0m. After what time interval does it strike the ground.
so i went through the problem and ...
2
votes
2answers
73 views
What's the meaning of dimensionality?
I got amazed with this answer and as you can see, I had a little talk with joriki. He suggested me some examples such as the 2DEG. I'm stuck with some aspects on dimensionality, see this line:
A ...
4
votes
4answers
482 views
Why the breath sometimes warm and sometimes cold? (2 different explanations!)
If you blow air against your hand with your mouth open, you feel warm breath. If you do with with your lips closed except for a small opening, you feel cold breath.
One explanation from here says ...
0
votes
0answers
309 views
When is a quantity “non-physical”? [closed]
The wikipedia says
A physical quantity is a physical property of a phenomenon, body, or substance, that can be quantified by measurement.
Formally, the International Vocabulary of Metrology, 3rd ...
12
votes
11answers
5k views
How do you start self-learning physics [closed]
I think this question has its place here because I am sure some of you are "self-taught experts" and can guide me a little through this process.
Considering that :
I don't have any physics scholar ...
0
votes
1answer
140 views
is there any difference between these Differential $dx^2$ and $(dx)^2$? [closed]
is there any difference between these Differential $dx^2$ and $(dx)^2$!?
what is relation between them?
4
votes
5answers
805 views
Can a scientific theory ever be absolutely proven?
I personally cringe when people talk about scientific theories in the same way we talk about everyday theories.
I was under the impression a scientific theory is similar to a mathematical proof; ...
0
votes
2answers
97 views
Weight on planet earth?
I was wondering :
does the weight on the planet earth is equal over the years ?
meaning :
all the people , ground , water ,gas.
does the weight stays the same over the years ?
1
vote
1answer
47 views
Why is it that when you pick up a cup from a stack of solo cups too quickly, they stick together?
Intuitively I think it makes sense but can somebody explain very clearly to a non-physics person why it is that when you pick up a cup from a stack of solo cups very quickly, the cup below it seems to ...
3
votes
1answer
191 views
interpretation of Green function
Is there a physical interpretation of the existence of poles for a Green function? In particular how can we interpret the fact that a pole is purely real or purely imaginary? It's a general question ...
0
votes
0answers
207 views
(where) Can I buy a miniature Foucault pendulum? [closed]
Or are they not made to to air resistance being too high a factor?
I think it would be really cool to have one on my desk in my room. I could start it when I wake up and then a few hours later see ...
3
votes
1answer
4k views
Is there any significance to 1.21 GW?
In connection with a related question on Science Fiction & Fantasy Stack Exchange page: does this number 1.21 GW make any sense? What is 1.21 GWatts? With what can you compare it? Can the ...
0
votes
4answers
251 views
Age of universe estimates
I was recently involved in a discussion on a sister site regarding how tightly coupled Physics is with the age of the Universe (and Earth).
I believe that the Earth and the Universe are both billions ...
0
votes
1answer
69 views
Are a measured object always part of the theory?
Is there a notion of measurement, which doesn't correspond to a yes/no question or with the idea of the comparison of two real world objects, which produces a real number?
And does at least one of ...
2
votes
8answers
573 views
What are the frameworks of physics?
Are there physical theories in use, which don't fit into the frameworks of either Thermodynamics, Classical Mechanics (including General Relativity and the notion of classical fields) or Quantum ...
2
votes
2answers
573 views
Please recommend a good book about physics for young child (elementary school aged)
I'm looking for a book that would be appropriate for an advanced elementary school aged kids (say, 6-11 YO) describing the basics of physics (or sciences in general) in entertaining way.
The ...
2
votes
3answers
289 views
What does physics study? [closed]
Wikipedia definition: Physics (from Ancient Greek: φύσις physis "nature") is a natural science that involves the study of matter[1] and its motion through spacetime, along with related concepts such ...
6
votes
3answers
779 views
Interesting topics to research in mathematical physics for undergraduates
I'm planning on getting into research in mathematical physics and was wondering about interesting topics I can get into and possibly make some progress on.
I'm particularity fond of abstract algebra ...
6
votes
4answers
406 views
What is the physical definition of causality?
Maxwell's equations give a physical relationship between the electric and magnetic fields $\vec E$, $\vec B$ at the same time, which some interpret as changes in one causes changes in the other etc. I ...
3
votes
1answer
696 views
Cooking pasta: why does adding a lid lead to overflow?
When cooking pasta, some organic foam usually forms on the surface of the boiling water and the situation can be kept under control by adjusting the heat (and/or adding some oil).
Covering the pot ...
12
votes
2answers
4k views
Why can't energy be created or destroyed?
My physics instructor told the class, when lecturing about energy, and that it can't be created or destroyed. Why is that? Is there a theory or scientific evidence that proves his statement true or ...
8
votes
4answers
233 views
What fundamental principles or theories are required by modern physics?
We have been taught that speed of light is insurmountable but as we know an experiment recently tried to show otherwise.
If the experiment did turn out to be correct and confirmed by others, would ...
1
vote
0answers
80 views
Practical personal aircraft today? [closed]
Is it possible to build, today, a personal aircraft that not use an impracticable amount of fuel for everyday use? What are the physical concepts that could be used to build it?
2
votes
2answers
461 views
Why does a balloon spiral in air instead of moving in a straight line?
When an air-filled balloon is released without its opening tied up, it moves in a circular path rather than a straight line. Why is that?
PS: I don't know what to tag this question as.
2
votes
1answer
459 views
How does a V formation save fuel for the lead plane?
I'm watching an episode of Mythbusters where they show aircraft saving 3-5% fuel when flying in a tight V formation. Interestingly, this also applies for the lead airplane.
How is that possible for ...
7
votes
5answers
684 views
units and nature
I am wondering whether the five$^1$ units of the natural unit system really is dictated by nature, or invented to satisfy the limited mind of man?
Is the number of linearly independent units a ...
-3
votes
2answers
452 views
Why Are Maxwell's Equations Preferred Before Those Proposed by H. Hertz?
In a recent exchange it was pointed out that in certain situations Maxwell's equations need Lorentz force as a patch (the latter not being part of those equations neither is it derivable from them).
...
0
votes
0answers
39 views
Anyone Know Details About the New Nobel Prizes in Physics and Chemistry? [closed]
The physics prize seems to be in astronomy but, I guess, that falls into the realm of physics for the lack of a separate astronomy prize. The chemistry prize, however, seems to also belong to physics ...
0
votes
2answers
347 views
Inertial and non inertial frames of references
I've heard from a physics professor that there's no stationary platform to observe and analyze a body in motion.Why did he mention that? Is it because even seemingly stationary objects like a parked ...
1
vote
3answers
6k views
Uses of Vectors In Real Life
I always wonder how vectors are used in real life.Vectors and decomposition of vectors,dot and cross products are taught in the early stage in every undergraduate physics course and in every ...
5
votes
2answers
296 views
Old Russian Physics Papers?
Where can one find old Russian scientific papers in physics, say, in the Proceedings of the Russian Academy of Sciences or Zhurnal Eksperimentalnoy i Teoreticheskoy Fiziki? Can they be found online ...
6
votes
2answers
626 views
Hydrostatic friction: why do water droplets stay at rest on an inclined glass surface?
Tjis is a non-expert question on a (seemingly simple) text-book topic.
The question is about "hydrostatic friction", defined as follows.
Consider a drop of water resting on a flat surface. If the ...
0
votes
0answers
151 views
Why do we fall when we ride bicycle slowly but we don't when riding it fastly [duplicate]
Possible Duplicate:
Why doesn't the bike fall if going with a high speed?
Why is it that, when we ride bicycle at good speed, it is perfectly balanced and we don't fall. But we lose ...
3
votes
3answers
292 views
Is there any physics behind flocking?
There are many articles published in physics journals about flocking. Is there a physical reason for these phenomena or is it just because physics methods are being used to study collective motion?
...
-4
votes
1answer
348 views
A new idea on unifying sound and light [closed]
Got a new idea regarding the unification of light wave and sound wave into a single entity , may be probably a wave. Is it possible to proceed in that manner,and has it been done previously,like i ...
1
vote
2answers
177 views
Publication Authorship Credits
Many physics papers now have dozens of authors per paper. Experimental physics may have multi-organizational and multi-country contributing staffs, but I'd guess that most of the names don't ...
7
votes
2answers
5k views
Why do car keys have longer range when held next to your head?
I first saw this on Top Gear, and assumed it was a load of rubbish, but today I tried it out and it actually works, if you walk away from the car continuously unlocking/locking it until it stops, and ...
