Mystery — 395 discussions

We know the answer, but don't know how it makes sense given trigonometric principles. Borrowed from HiSet free practice test

While I am reading this article, it says moment of inertia is same at radius of ring and at the center of it. How is that possible?

"An international team has constructed the most detailed, highest resolution simulation of a black hole to date. The simulation proves theoretical predictions about the nature of accretion disks—the matter that orbits and eventually falls into a black hole—that have never before been seen. The...

we know that when a electron lost its energy , it will emit photon , but why electron have a photon inside ? does it already exit in a electron from the beginning or it comes from environment ? if comes from environment , where does photon come from?

A friend of mine got this from an estate sale today. We're trying to figure out what it is. top view: Side view lying flat, moving parts sticking out further than central part: Center pulled up, moving parts pulled in toward center: I'm think if used upside down, it could be lowered into...

If you change the spin of an entangled particle without knowing its original spin, what happens to the other entangled particle?

I thought I'd create a new thread rather than derail. In https://www.physicsforums.com/threads/if-quark-stars-exist-why-do-neutron-stars-become-black-holes.937452/#post-6143231 it was explained to me that gravitational waves do not escape the interior. The reason I thought they did is that we...

When photons from distant stars [etc] are received why does the rest of the electromagnetic spectrum not reach us.

Greg Bernhardt submitted a new blog post Wigner's Friend Continue reading the Original Blog Post.

Hi, I was wondering if there are any proposed ideas for the mystery particle at 28 GeV? Please see article http://theconversation.com/mystery-particle-spotted-discovery-would-require-physics-so-weird-that-nobody-has-even-thought-of-it-106260

In Abraham Pais book (which was first published in 1982), he states the following: "Quantum field theory has taught us that particles nevertheless have structure, arising from quantum fluctuations. Recently, unified field theories have taught us that the mass of the electron is certainly not...

Mystery particle spotted? Discovery would require physics so weird that nobody has even thought of it http://flip.it/Y6A5he Could be DM ? Or really an error

A new form of ice has been discovered dubbed ice VII: https://arstechnica.com/science/2018/10/weird-water-phase-ice-vii-can-grow-as-fast-as-1000-miles-per-hour/ https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.121.155701

What would cause a hole to form in the top aluminium tank of a radiator of an earthmoving machine. The tank material is 6mm thick and is made from 1050 aluminium plate. The material around the hole has bubbles almost like pitting corrosion or like somebody went and took a flame to it. The rest...

It is 9:45 am in my city in British Columbia, and it is pitch black. All the streetlights are on!

It has been an unusually hot summer where I live. I am not surprised to be getting ads for 'room coolers' due to this. However are not such devices contrary to well known physics? In regions where hot summers are usual. air conditioners are used, they pump the excess heat outside. How though can...

If atom are invisible then how can one say that atoms are made up of electrons nucleus and quasi particles.

Plasma ball has a high voltage. Why don't we get an electric shock when we touch it?

Question: There are three non-negative integers with the following property: If you multiply any two of the numbers and subtract the third number, the result is a perfect power of 2. Find these three numbers that satisfy this property. My attempt: I worked out that the three numbers must be...

I'm trying to learn more about this alloy and there is scant little on Google. William Godfrey Lecomber created a copper alloy for use in frictionless bearings and apparently huge amounts were sold to America and South Africa. WGL called the alloy Cantaba and named his farm in Ruthin (which he...

What if the mystery of unified theory is solved (i.e we found a TOE)? What would be the next mystery in physics(will their be any or will the context of physics would be completed(i don't think so,what do you think?).

I'm having a difficult time understanding why the internal resistance of the EMF source is disregarded in this problem. 1. Homework Statement You are asked to determine the resistance per meter of a long piece of wire. You have a battery, a voltmeter, and an ammeter. You put the leads from the...

A Mystery re Fluorescent Lights I have a fixture F1 from the 1960s with two 2' fluorescent lights B1 and B2. Recently they both began to flicker. A second fixture F2 has a single 2' light B3 which did not flicker. In F2 I replaced B3 with B1. It did not flicker. I then replaced in F2 B1...

It will be interesting to see what comes of this. https://www.yahoo.com/news/homo-naledi-mystery-human-species-091635429.html

When a heating experiment for example when measuring the specific heat capacity of an aluminum block, why is it practical to turn the heater off and wait for the highest temperature reading on the thermometer and take that reading. Why does the reading even rise when the heater is turned off...

I have noticed a phenomenon I cannot explain in my kitchen. Whenever I place a warm object on the granite counter [e.g. plate from microwave], when I remove the object, the counter is covered with moisture where the object was. I'm guessing it is condensing from the air due to the temp...

Hello everyone, This is my second year teaching Physics and I have come upon an interesting apparatus that no one can seem to identify. It appears to be two vacuum tubes protruding from a casing which includes two sets of three parallel brass plates, presumably with some sort of dielectric...

Why do we exhausted sometimes even when no work(in terms of science) is done.where does our energy go?

If \[x^{x-\sqrt{x}} = \sqrt{x}+1\]- then what is the value of \[x + \frac{1}{x}?\]

Hi This example of KEnergy and resistance seems incorrect. Sabot. An artillery projectile with narrow core and wide plastic rings to give energy to smaller drag . .. "This, in combination with the sub-projectiles’ higher sectional density, gives the resulting sub-projectile vastly reduced...

I recently got a 5 cm high radio tube from a old radio in my house. It has 9 pins ,arranged in a C shape at the base, a getter at the top and parallel metal plates inside. I decided to use my GMC-300E plus ,Geiger counter to check if it had a thoriated cathode. It did not. Just for fun, I two...

Today I was leading my students in an experiment that would reveal "the rule for what floats." We had previously floated (or sank) various objects in regular, room temperature tap water. I then weighed out 100 grams each of sugar and water, mixed them together and weighed them again. To my...

List contains 1, square root of 2, x and x squared and the list range is 4. I guessed 2 but it is not correct.

There is a well known rule of thumb amongst sailors that a boat has a theoretical maximum speed called the hull speed, given by v_h \approx 1.34 \sqrt{L_{wl}}, where LWL is the waterline length of the hull. This so-called rule is pretty much complete rubbish; a boat can overcome this speed with...

What is exactly the dark matter? There are lot's of things hitting at a particle nature of dark matter I mean observation of the bullet cluster, freeze out times in the earlier universe, the third peak in the CMB power spectrum. I think there is no known consistent explanation by modified...

Hey guys, Regarding the cosmic void between galaxies, is it really empty? If you read articles from pop science sources mostly said "cosmic voids are devoid of matter", "there are full of dark matter", etc. Thoughts?

Hi guys, I recently extracted a motor from an old washing machine and came across some really interesting things when I hooked it up to a D.C. power pack. Firstly, I connected a lead to each brush and powered it will 12V D.C. and it span really fast. I cannot work out why because the startor...

Hello everyone. As far as I know, any unit can be expressed in terms of basic units: time, length and mass. It quite clear that we could choose them differently but in any case we get three units as the base.. And I ask: Why? What fundamental properties of nater make it It happens that any...

hi guys, I'm new to this beautiful forum and i signed up to ask a question that drives me nuts for weeks. I am german so my english sucks but, i learned about this experiment with the quantum eraser. basically the experiment goes like this. you shoot photons through a double slit and behind the...

it's not all that sophisticated but it has given a hard time even to some math people. 3 people on a trip go to a hotel to get a room to spend the night in. the desk clerk just happens to not be there, so the bellhop says can take care of you but I'm not sure how much a room cost, i think...

Hi, It's known that ## \bar{\psi}_L \psi_L = \bar{\psi} \psi_L## I tried to work this out but i do not reach that Here what I do : since ## \bar{\psi} = \psi^\dagger \gamma^0##, and ## \gamma_5 \gamma_0 = - \gamma_0 \gamma_5 ## then ## \bar{\psi}_L \psi_L = \frac{1}{4} (1-\gamma_5 )...

Hello everyone, I have been thinking about binaural beats, and after learning about the inner workings of the ear, there is something that I cannot explain. A binaural beat is the pulsating effect perceived by the brain when slightly offset frequencies are played in each ear. In my example...

Has anyone an idea where these X rays come from? https://www.sciencedaily.com/releases/2016/09/160926104700.htm From Science daily, Space is filled with types of light we can't see -- from infrared signals released by hot stars and galaxies, to the cosmic microwave background. Some of this...

Why we sleep is said to be one of the greatest unsolved mysteries of science. Haven't they cracked it yet? is there any animal or even living system that doesn't sleep?

I build new desktop computers every few years and I like quiet machines. Hard drives (to my ears) are noisy, so my last four machines have used a combination of solid state drives and spinning lap top drives. When I use any of these machines I hear faint sounds that I've always interpreted as...

For some time now there has been a phenomenon in my home that I consider to be a mystery, since I do not understand it. I am hopeful that someone at this site may have a helpful suggestion. My home was built in 1962, and the florescent light fixtures are the original hardware. Our kitchen has...

My teacher told me the other day that a semiconductor does not have a fermi surface. I didn't understand this remark. As I understand it the Fermi Surface is just the surface in k-space spanned by the highest occupied energy levels. Surely in a semiconductor you will also have some highest...

Homework Statement Ball lightning is a sphere shaped lightning that stays long before it explodes. they are sometimes created in a lightning storm. The theory says they are made of nitrogen ions surrounded by water molecules. the temp' inside is 6000C and outside 200C. Nitrogen: ##N_7^{14}##...

Hello, I am new to this forum. I work at a major science museum in the US. I have been thinking a lot about gravity lately, and would like to start a general discussion on this topic, especially because of the recent discovery of gravity waves, the higgs field, as well as some of my own, less...

How do the northern lights work? I have already know why it emits light, but why in waves? Why does it move? Are the particles that excite oxygen the ones that were deflected, or the ones that were already heading straight towards the Arctic Circle? Feel free to post any questions as they come...