Questions in this tag must be answered in a manner that can be understood by a general audience with at most a basic understanding of physics, mathematics and related sciences. Apply it to questions where the asker clearly requests such answers.

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1
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3answers
135 views

How is this possible that photons are absorbed?

From the lessons on QM, I got impression that there are some discrete orbitals that emit light when electron drops from one to another. Specific molecules emit light in very narrow bands, therefore. ...
2
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1answer
85 views

How does a tightrope walker return to equilibrium?

I do not understand how tightrope walkers return themselves to equilibrium. I am not concerned with the direction along the rope or wire where their base can be large, and they are able to move ...
0
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0answers
49 views

Is this a good explanation of electron mobility to the layman?

I'm writing an informative paper on graphene for my writing class (layman-oriented), and was describing electron mobility in very simplified terms. Let me know if anything is mistaken, badly ...
0
votes
0answers
12 views

How 2nd-order nonlinear optic response is used in the telecom market?

References According to this paper, 2nd order NLO response is important for telecom. According to Wikipedia, Lithium niobate is used extensively in the telecoms market, e.g. in mobile telephones ...
0
votes
1answer
73 views

Scientific Laws for Engineering Materials [closed]

I have a conceptual question. There is a law in science for every phenomenon in nature, like gravity or electric field. But also there are laws for springs or capacitors etc... I mean the ...
1
vote
3answers
129 views

Why did scientists need to invent light years?

Why did scientists need to invent light years? What's so important about having a light year? I have been learning that a light year is $9.461 \times 10^{15} \, \mathrm{m}$. My question is, why are ...
2
votes
1answer
60 views

The fly and the sphere of iron

When I was a child, I read something like the following in a book whose name I have now forgotten (I tried to find the original quote on the web, but although there are some similar passages the ...
6
votes
3answers
528 views

Why are gasses difficult to see? [duplicate]

Why are gases difficult to see?
4
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1answer
118 views

String Theory: Why should(n't) the string snap?

My question is related to a comment in the margin of the popularising site The Official String Theory Web Site. There are two basic types of string theories: those with closed string loops that ...
0
votes
1answer
906 views

Does car colour affect car temperature? [duplicate]

My family will buy a car, so to minimise the car's air conditioning and heating (and thus fuel) costs, how should we choose a car exterior's colour and the interior's colour and material (eg fabric ...
0
votes
1answer
51 views

Can rotational motion can be reduced to translational motion?

Susskind says that all physics (dynamics of the world) can be described in terms of particle positions and their first order derivatives. Does such translational motion gives rise to rotation?
0
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3answers
223 views

How much does the Earth's population affect the force of gravity? [duplicate]

If everyone on earth except one person were to gather up in one location, say the North Pole, and jump at the exact same time and stay airborne for about 1.5 sec. And that one person who did not jump ...
31
votes
2answers
7k views

What are Stephen Hawking's main contributions to research-level physics?

Without a doubt, Stephen Hawking is the most famous living scientist; indeed, his public visibility in all of history seems to be rivaled only by Einstein and easily eclipses giants of physics such as ...
15
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1answer
816 views

Which hemisphere am I on?

Inspired by this answer to a question on Puzzling.SE (which contains the old but wrong idea that the Coriolis force determines the direction in which a bathroom vortex rotates, and also an approach ...
3
votes
2answers
124 views

Food calories vs gravitational potential energy [closed]

Imagine you could use all of the energy you have ever extracted from your food as a source of propulsion. Is the energy contained in the food you’ve eaten over the course of your lifetime enough to ...
1
vote
0answers
77 views

A model that predicts the universe is finite in space and time

A physics professor talked in a YouTube video about a paper he and his colleagues published. The paper presents a model that ties the mass of particles to the size of the universe. He summarizes their ...
1
vote
0answers
32 views

What forces are involved to enable a rock to skip in water?

Does the surface tension matter or is it something else that is providing the upward force? Can someone explain the phenomenon to me physically?
27
votes
4answers
7k views

Blowing your own sail?

How it this possible? Even if the gif is fake, the Mythbusters did it and with a large sail it really moves forward. What is the explanation?
2
votes
2answers
119 views

Scientists observe the laws of the physics but, Where do they come from? [closed]

Has anyone ever considered how the laws of physics that we study came into being.
2
votes
1answer
93 views

Why aren't train headlights brighter? [closed]

I suspect a valid scientific, physics answer for this question, because I'd venture that train, insurance companies would've calculated and contemplated this question. Yet the train headlights at ...
63
votes
5answers
7k views

How literally should you take “The Higgs boson gives other particles mass”?

A standard phrase in popular discussions of the Higgs boson is that "it gives particles mass". To what extent is this a reasonable, pop-science, level of description of the Higgs boson and it's ...
5
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1answer
1k views

How could we travel to the nearest supermassive Black hole?

I have just watched a trailer for the upcoming movie Interstellar and started to wonder about some physics involved. In the end of the trailer, they are obviously plunging into a Black hole hoping to ...
2
votes
1answer
96 views

Are these guard rails truly strong enough?

I'm lay about physics, but I'd like to learn about it behind this question. A friend criticises and claims that the single strip of traffic barriers (as shown below) would fail and is useless. For ...
2
votes
0answers
104 views

Are the elements of physics different on the upper deck, of a double-decker bus, than those on the lower deck? [closed]

In this question, I hypothesise an event that affects the entire bus; I'm not asking about menace unique to upper floor passengers, such as an overly high upper floor or hanging objects (because this ...
2
votes
1answer
121 views

Does the Night Mode of the screen display (LCD) save more energy?

In some cases, we can enable the Night Mode (reversing the bright and dark color of the display; such as White Text, Black Background) for the screen display. LCD(Liquid-crystal display) seems to be ...
4
votes
1answer
104 views

Quantum field theory defines its own bounds of applicability

I recall hearing in a lecture something along the following lines: "Due to some intrinsic feature of quantum field theory in general (or maybe it was the standard model?), we know where it is ...
0
votes
1answer
52 views

Does the ground beneath a levitating object change due to the rotation of the earth? [duplicate]

I don't know whether this question pertains to physics. But anyways, here goes... If I were to hover 1m above the ground in a helicopter, would the ground below me change after 1 hr due to the ...
3
votes
1answer
213 views

Difference between horizon and flatness problems & how inflation solves flatness (w/out math)

Layman here so I'm hoping for an answer for my query that doesn't involve math. I'm reading about inflation and how it solves the flatness and horizon problems. I get that the horizon problem deals ...
3
votes
1answer
267 views

Does decreasing the length of the line between a harness and zip wire increase the velocity at which you travel?

My friend is an instructor at an outdoor adventure centre which has lots of zip wires. The instructor's harness has a shorter line that attaches to the zip wire than the normal harness does and she ...
1
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1answer
289 views

So physicist's really do think the Universe could be a holographic Illusion?

http://www.nature.com/news/simulations-back-up-theory-that-universe-is-a-hologram-1.14328 http://guardianlv.com/2013/12/compelling-evidence-says-our-universe-is-a-hologram/ I thought the holographic ...
3
votes
4answers
126 views

Coherence effect on collecting sun light by mirrors

There are systems that collect sun light in one spot. I wonder, why does it accumulate additively, without destructive interference?
-1
votes
1answer
119 views

What is the physics concept in sponge filter

I really need help I want to ask what is the physics concept in Sponge Filter?
2
votes
2answers
580 views

Behaviour of duvet covers in washing machines

When you put a duvet cover in a washing machine without buttoning it up any other items of bedding (e.g. pillow cases) inevitably end up inside it. Instinctively, I would think that the opposite would ...
1
vote
3answers
1k views

Is a real life electric shield possible? [closed]

I got this question from playing games like Halo and Borderlands (I know kinda dumb but raised a good question) in which the primary protection is an electric shield. Now I'm wondering if it would be ...
0
votes
0answers
90 views

Is that true that neutron activity on Earth in 2013 is unusual?

I have just read curious statement on this website: http://www.trinitas.ru/rus/doc/0016/001d/00162241.htm (unfortunately this is in Russian, but I will try to translate) "В заключение можно отметить, ...
5
votes
2answers
259 views

Better explanation of the common general relativity illustration (stretched sheet of fabric)

I've seen many science popularisation documentaries and read few books (obviously not being scientist myself). I am able to process and understand basic ideas behind most of these. However for general ...
2
votes
1answer
408 views

Black Hole evaporation through virtual couples at the horizon

I read about vacuum energy. It explains the Hawking radiation, the black hole necessary radiation: Physical insight into the process may be gained by imagining that particle-antiparticle ...
1
vote
3answers
855 views

Whats left at the center of the Universe after Big bang?

If you consider big bang. According to that What's left at the center of universe where the Big bang occured?
5
votes
1answer
129 views

Predominant light frequency over the day?

I'm not well-versed in physics, so I hope you'll forgive me if this question is significantly off the mark. I'm interested in the predominant frequencies of light over the course of one day. My ...
4
votes
1answer
225 views

Revisiting the microscopic concept of Touching with some more questions

This question is regarding the amazing answer given by Terry Bollinger at this Phys.SE post. I think this answer is very helpful but i do have some standing questions. He says Once the bonding ...
7
votes
2answers
562 views

Is there an intuitive way of thinking about the extra dimensions in M-Theory?

Why are 11 dimensions needed in M-Theory? The four I know (three spatial ones plus time) have an intuitive meaning in everyday life. How can I think of the other seven? What is their nature (spatial, ...
16
votes
6answers
1k views

How to argue that time travel to past would not be possible even in future?

I am a science fiction writer. I know how to time travel to the future (using black hole or speed). But I need to argue in my novel that time travel to the past might not be possible. Is there a way ...
6
votes
3answers
2k views

What are the fundamental problems of being in a 2 dimensional world?

I was reading through Stephen Hawking's explanation of two - dimensional space. In that he mentioned that it will be very difficult to design a living being that could exist only in 2 dimension. What ...
1
vote
2answers
200 views

What is the universe expanding into? [duplicate]

Due to curiosity, it made me wonder what is outside of the universe, is it a new chemical or just empty space? But empty space have protons appearing and disappearing in it, it basically still has ...
-4
votes
2answers
2k views

Is the total mass of the universe constant in time? [duplicate]

Is the total mass of the universe constant in time?
4
votes
1answer
228 views

Identifying the position of the moon

I encountered the following question in a previous year paper of a graduation-based test. On a certain night the moon in its waning phase was a half-moon. At midnight the moon will be (choose one ...
6
votes
5answers
7k views

Is coherent light required for interference in Young's double slit experiment?

In this Veritasium video, a home experiment is presented which appears to produce a very good double-slit interference pattern with normal sunlight. The experiment is an empty cardboard box with a ...
0
votes
2answers
486 views

3 Questions about modern Physics [closed]

First i'd like to apologize for both my writting skills (i'm not english) and for my physics knowledge (being them very basic and/or naive). With general relativity from Einstein, gravity is no ...
2
votes
2answers
301 views

Many-worlds interpretation vs 'just' randomness?

I have this question about MWI I always wanted to ask but never dared to! It could be that I just don't know enough physics to understand the answer, or the question! Anyway, here goes: What is it ...
0
votes
1answer
382 views

Time travel, is it possible? [duplicate]

I see there are many questions with this title, but this one is different, so please give it due thought: Is time travel possible? If so, Can we go both forwards and backwards in time? Paradox: I ...