Questions tagged [physics]

Use this tag for questions about the physical nature of reality and in particular claims that are strictly about the field of physics. Please use specific tags if the question is about other sciences such as chemistry. Also consider to add [electromagnetism] and [radiation] if appropriate.

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12
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1answer
12k views

Was the periodic table discovered in a dream by Dmitri Mendeleyev?

Did Dmitri Mendeleyev conjure the organization of elements into the periodic table in a dream? Among the several places I've seen this suggested is the review of a book (that I haven't read) on ...
20
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1answer
6k views

Is breaking bricks/wood "karate style" an impressive feat?

Related: How do Shaolin monks break spears with their neck? For anyone unacquainted with the fairly impressive looking feat of breaking bricks (or wood) in martial arts, see THIS 1.5min video. I'd ...
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1answer
2k views

Lawn umbrella as a parachute?

Just saw in a movie, a guy jumped off a building using a lawn umbrella as a parachute. Would that work in reality?
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1answer
447 views

How powerful are air cannons?

I wondered how powerful air blasters are. Is it possible for one to be so powerful that the shock wave passes through walls, floors and ceilings? Could it make bumps on metallic surfaces or at least ...
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4answers
1k views

Is ET watching "I Love Lucy" right now?

Is it realistic to suppose an alien civilisation 60 light-years away could now be receiving tv transmissions of "I Love Lucy"? This site says emphatically not, but my brother say ET could easily do ...
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2answers
2k views

Ultrasound pest control devices

A couple times I've seen advertised on TV and in supermarkets electronic devices that allegedly irritate all sort of insects and rodents, such as mosquitoes, mice, and rats, forcing them away from the ...
29
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1answer
69k views

Is leaving your AC fan (blower) on 24/7 during summer more efficient than leaving it on auto?

The AC guy that fixed my AC recently said I should turn my AC fan on 24/7 and this would increase the efficiency of my AC system. I looked it up and found this same claim in several places: City Data ...
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3answers
31k views

Do knives get dull in dishwashers?

Everybody keeps telling me don't put knives in dishwashers. And if I ask them why, nobody seems to have an answer or an argument to support his/her advice. So I thought I'll shoot the question to ...
38
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2answers
39k views

Can you recharge non-rechargeable alkaline batteries?

There are conflicting reports of whether it is possible to safely recharge alkaline batteries (not lithium) that are not sold as rechargable. The packaging for batteries regularly has cautions ...
12
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2answers
7k views

Does the Karpen Pile work, producing continuous energy without refueling?

According to Wikipedia, the Karpen Pile is: claimed by some to be a battery that has provided continuous energy for over 60 years, making the Karpen Pile either a supremely effective method of ...
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2answers
2k views

Is this magnetically-controlled balls video fake?

This video shows a cool trick involving a powerful electromagnet and balls with controlled electromagnets inside them. The result looks very cool. According to the video, the balls are controlled by a ...
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2answers
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Is there "vastly more matter than anti-matter" in the Universe?

From the Register, talking about the recent CERN antimatter experiment. I'm not concerned with the experiment itself, but rather this claim This, in turn, would help us understand how come our ...
16
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1answer
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Is it necessary to leave a pool during a thunderstorm?

Most schools and public pools have the policy of closing swimming areas during thunderstorms for fear of electrocution. I was wondering how logical or reasonable this policy is, given that most pools ...
8
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2answers
608 views

Did an X-ray burst interrupt radio signals shortly after D-Day?

I was told in the bar at a wargames convention about an event that is supposed to have taken place on 7th June 1944, when suddenly the Allies lost all radio communication. There was a great deal of ...
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5answers
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Are there more 40-moves chess games than atoms in the universe?

I read this tweet recently: "There are more possible games of chess lasting 40 moves than there are atoms in the entire universe. Intriguing to know." I find this highly doubtful. Could ...
27
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1answer
5k views

Is it possible to obtain current indirectly from power lines?

Can one obtain a sufficient amount of energy for a household's needs by indirect means (induction or otherwise) from nearby high-voltage power lines? Are there any documented cases of such attempts (...
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3answers
65k views

Can cats survive a fall from any height?

So here's the premise. A cat reaches its terminal velocity after around 10meters of free fall. A cat can survive a landing from a speed equal to its terminal velocity. Therefore a cat can survive a ...
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4answers
31k views

Does hot water freeze faster than cold water?

Is it true that hot water freezes faster than cold water and if so, what practical applications have there been found for this phenomenon?
185
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1answer
21k views

Do cats always land on their feet?

Assuming a fall from a survivable height, will a cat always land on its feet? Has this been studied? Is there real data to back it up?
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5answers
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Does the theory of evolution contradict the second law of thermodynamics?

I was reading about the Law of Thermodynamics, and the Second Law of Thermodynamics really interested me because the Law apparently stated that in any isolated system, the entropy of that system will ...
12
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1answer
1k views

Subway magnetic fields and laptop hard drives

I just heard a story of a guy who took the subway to transport his company's off-site data back-ups for storage. When the time came for restore after a disaster, the data was corrupt and erased. ...
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2answers
2k views

Can products that claim to to reduce electromagnetic radiation from mobile phones be substantiated?

There are some products, stickers that you put onto your mobile phone for example, that claim the following Boost your natural defenses in the presence of electromagnetic radiation (EMR) ...
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2answers
7k views

Is alcohol for consumption tested for carbon-14 radioactivity to be considered legal?

I just viewed this interesting video about radioactive ethanol from plants as opposed to non-radioactive ethanol from crude oil. In it, the professor says he's heard it's illegal in the USA to sell ...
35
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1answer
22k views

Reading while lying down is more strenuous (unhealthy) for eyes

My friend heard that reading while lying down is more strenuous (unhealthy) for eyes. I like reading in bed (books, tablet). Is there some study that confirms this hypothesis? I use two positions (...
28
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1answer
2k views

Is modern String Theory stuck in the "no predictions" land?

Back when I was interested in theoretical physics (>15-20 years ago), String theory was the Hot Thing. Imagine my surprise when, in a random browsing, I stumbled upon a science-themed blog "...
12
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2answers
953 views

Are there no two snow crystals alike?

I remember vividly that when i still was young, I'd examine the snow as it dropped on my winter cloths. Every time I was amazed by the nice textures I discovered. Now many years later, I'm wondering ...
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3answers
3k views

Is there any observable evidence of the Big Bang? [closed]

Is there any observable evidence of The Big Bang?
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4answers
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Is there hard science behind the benefits of home water softeners? [closed]

Does anyone know of any empirical studies or well-tested scientific theories on the benefits (or lack thereof) of using a home water softener? I have a water softener in my house that we installed ...
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0answers
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Risks of using a cast iron skillet on a flat/glass top electric range?

There are many claims about possible risks of cooking with a cast iron skillet on a flat/glass top electric range: the glass top can break if one is not careful; the glass can be scratched; the glass ...
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6answers
4k views

Is K-Ar a reliable method for dating rock ages?

Firstly: please try not to bring creation/evolution into this. I will award the correct answer to a response which provides links to evidence and sound explanations. Motivation for the question to ...
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2answers
2k views

Is there anything inexplicable about how the WTC Twin Towers collapsed? [duplicate]

Possible Duplicate: On 9/11, was Building 7 destroyed in a controlled explosion? Having just watched the movie Zeitgeist, I'm a bit unsettled because I don't know how to refute the idea that the ...
6
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1answer
2k views

Did Tesla say that one could get or transmit energy through thin air [duplicate]

Possible Duplicate: Can you create energy out of nowhere ? I recall reading that Nikola Tesla suggested that electricity could be created from the air. This claim is stated in the following quote ...
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5answers
6k views

Is it possible to get to the power needed to thrust a rocket so that it can escape from earth?

Note: Any velocity mentioned in this question is the velocity relative to the earth. Warning: Base your answers on formal proof and facts, moon images aren't really science... According to this book ...
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2answers
6k views

Does earthing reduce oxidative stress and inflammation?

The other day my friend asked what I think about "earthing" claiming that their products provide electrons we used to get from walking barefoot on the earth surface and that they have positive (...
16
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2answers
417 views

Japan's earthquake and the Earth's axis

I've been hearing a lot lately about how Japan's massive earthquake moved the Earth or changed its axis by 1°-4°. I personally feel that this is not possible, but I don't have nearly enough knowledge ...
14
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2answers
7k views

How can we know meteorites found on Earth came from Mars?

ALH84001 is a famous meteorite found in Antarctica. Scientists have since claimed that (1) this meteorite came from Mars (along with several other meteorites), and (2) that it contained evidence of ...
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3answers
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Does the Mount Washington wind speed record have scientific validity?

A record wind gust of 231 miles/hour was recorded in 1934, according to http://www.mountwashington.org/about/visitor/recordwind.php Wind speeds of this magnitude are commonly known to damage or ...
224
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2answers
36k views

Has man walked on the Moon?

Is there any concrete, solid proof of this space odyssey? Is there a way that I personally have a look a it? Let's say, with a nice telescope ?
107
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5answers
7k views

Are personal electronics a risk to commercial aviation?

Are personal electronics (of present or recent past; e.g. cell phones, mp3 players, iPads) a risk to commercial air travel? Is the typical request to "turn off all personal electronic devices" based ...
21
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1answer
16k views

Do we lose 7 pounds when we die?

I often hear people claim that it is a fact that humans lose seven pounds when they die. Some people believe that this is 'proof' of the existence of the 'soul'. Is there any truth to this claim? I ...
12
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1answer
555 views

Can big earthquakes trigger a domino effect?

Can one earthquake trigger another? For instance, the quake in New Zealand, then the one in China and finally the big one in Japan. This does not count aftershocks, but separate earthquakes in ...
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4answers
2k views

Can a "second Chernobyl" happen at the nuclear reactors damaged by the tsunami in Japan?

In the media, you hear predictions that the events in the damaged nuclear power plants could be "the next Chernobyl", but this sounds like hyperbole to me. Are the events at those nuclear reactors ...
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4answers
36k views

Can bullets fired into the air kill a person when they fall?

Lately, I've been watching the Libyan civil war in the media, and both sides in the conflict often celebrate success by firing their AK-47s into the air. Not to say that firing guns into the air is ...
51
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3answers
140k views

Is it unsafe to swim during a lightning storm?

I was cautioned by mom that I mustn't go swimming when there is lightning; the theory is that it is more likely for lightning to hit you when you are in the water. Is this fear justified?
53
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4answers
12k views

Does water swirl the opposite way on the other hemisphere?

I have heard this one several times but was never given a convincing explanation. Is this a real phenomenon? (Bonus points for a good physical description of the behavior or reasons it couldn't occur....
16
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3answers
4k views

Can an electronic device reduce scale buildup in waterworks?

I have recently received an ad for a device attaching to my inlet water pipe and a power socket, and claiming to massively reduce the scale build-up. This compact, computerised limescale remover uses ...
25
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7answers
7k views

Are there technologies that provide unlimited free energy?

Many different sources claim to be able to produce "unlimited free energy". For example: UNLIMITED FREE ENERGY IDENTIFIED Company claims to have developed new technology that provides unlimited free ...
65
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2answers
8k views

Does water have a memory as claimed in homeopathy?

In homeopathic remedies the original substance is often diluted to a point where statistically there should be not a single molecule left of the original substance. The most common explanation by ...

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