Cause Definition and 572 Threads

Homework Statement What is the cause for the bump in the lower energies of this spectrum: http://en.wikipedia.org/wiki/File:Gammaspektrum_Uranerz.jpg The Attempt at a Solution Is it just normal Compton? I'm doubting that because that is very asymmetric. I can't find anything in any textbook I...

Regarding the thread St. Thomas Aquinas and "uncaused first causes", it appears the author is restricting causation to mean only an ordering of events into a "before" and "after," what Q_Goest perhaps means by saying that "the reductionist concept of cause and effect [...] may or may not be a...

Light normally doesn't interfere with itself because it is incoherent and unpolarized, right? So how is it that incoherent, unpolarized light passes through a circular aperture and interferes with itself? How does the aperture suddenly cause the light to be able to interfere with itself? In...

Homework Statement 1. There is a counterclockwise current I in a circular loop of wire situated in an external magnetic field directed out of the page as shown above. The effect of the forces that act on this current is to make the loop (A) expand in size (B) contract in size...

We learned yesterday that a voltmeter's resistance approaches infinity. And that infinite resistance means total disconnect. I'm trying to understand why is that? Why must a voltmeter's resistance approach infinity? Doesn't it mean that the voltage will be 0? BTW - I hope I'm translating...

Hi everyone. This is my first post and it's sort of related to homework because it's for a paper I'm writing for school but it's pretty conceptual so I thought I'd put it here. In Lewis Epstein's book Relativity Visualized, he says that it's actually the slowing of time rather than the...

What is the cause of Gravitation?

Ever since I have been taking psych meds, since I was 18 I think; my head and shoulders have grown really big. When I graduated from high school I looked completely normal, but now my head and shoulders are gigantic. Plus my back sticks out now. It is like I am a tall hunch back.

My friend told me that he heard from a friend that it does. I think it's a bit of a wild concept, but is there some validity in there if not any?

I am in business school and every year we do a charity event called hogs for the cause (http://www.hogsforthecause.org/ ). This year we are planning on putting a pig on a spit and have designed the cooking apparatus. I have combed craigslist and found an electric motor that should be able to...

Hi all, I was reading about eternal inflation however one thing that remains unclear to me is that how does one explain the force behind inflation, the word "force" is perhaps a non-technical term, the more precise term is "inflation field", the chaotic inflation model says that just...

First apologies for asking what is in all probability a misconceived question, but here goes. The accounts of the cause of lightning seems to explain it in terms of turbulence in high clouds causing ice particles to become electrically charged by bumping into each other. But this seems...

Prove that cause precedes effect in all inertial reference frames.

Hi all, I've been reading on phase changes that occur in manifolds such as flop transitions and conifold transitions for some time but I don't quite understand this one thing: flop transitions mathematically describe how one calabi-yau can change into another and most books mention that but...

Does consciousness cause thoughts? This question is central to the debate concerning free will. 1. Effect ( by definition) cannot precede cause. 2. It is impossible to be conscious of a thought before you think it. 3. Therefore, it is impossible for consciousness to cause thoughts.

This topic emerged in another thread but I find it interesting enough to warrant a new thread of its own. The premise is that GDP growth provides more money for investment, consumption, and other spending. To the extent that this extra money allows fiscal discipline to relax, it can have the...

Lightning is quite a common phenomena and yet i don't have a clear understanding of how it is caused. Can someone tell me the real cause of lightning?

The "cause" of entanglement / coupling Hi all, two questions. I don't have a physics background (but have a decent mathematical background, and have dabbled in QM). * What is the difference between entanglement and coupling? Wikipedia says they're "almost" the same thing, except for the...

Why does a can of soda "explode" when it's shaken? I looked online, but all the explanations were either very hand-wavy, or looked very wrong. Thanks!

If light travels through a perfectly transparent material, it will not be absorbed, and other than the reflection loss at the two interfaces, the energy that comes out will be equal to that which went in. Yet we know that the light field is causing all the atoms in its path to oscillate, thus...

1. The problem Remember that acceleration is a change in velocity. There are 3 driver-operated controls in an automobile that will cause the automobile to accelerate. 2. The attempt at a solution Is it axis of rotation, tangential speed, and uniform circular motion?

hi, at this site: http://www.amazing1.com/ultra.htm they have a device called a "phasor pain field generator" does it really cause pain and nausea etc? why does it cause any long term effects? why is there no scientific proof about this anywhere? lol jk thanks...

Hello everyone, I can understand how liver failure can cause jaundice, but not vise versa. Please help. Thanks :smile:

what causes the reflection of light from a surface?? why can't light simply move through the shiny surface that reflects it...ya difference in penetrating strength... if we try to explain it at the microscopic level... why would the particles of the shiny surface make it bounce back making an...

Hi! So I know what the Uncertainty principle states and everything, but I can't find anywhere the "causes" of the uncertainty. Like, what is it exactly that "causes" the uncertainty. If it's not the measurement tools/technology, then what is it?? Please explain in terms of physical phenomena...

Why does sun appear elliptical during sunset and sunrise? I have read that when the Sun (or Moon) is near the horizon, the rays from the lower edge are bent more than the rays from the upper edge. This produces a shortening of the vertical diameter, causing the Sun to...

If I rubbed my hands together in a dark room (no outside light source), could the heat i produce cause Infrared radiation? Or is the infrared radiation from our bodies dependent on outside radiation?

Suppose we have a wire and we pass electric current through it. When placed horizontally in a gravity field, the wire has some resistance. Now what happens, when we place this wire vertically? Suppose the electrons are flowing upwards. They have to counter gravity potential, so this should be...

Hi everyone! I'm simulating a gas mixture of He and Ar, and I'm trying to get them to separate via Thermophoresis. For clarification, http://en.wikipedia.org/wiki/Thermophoresis When I naively try it with what I have so far in my program, it exhibits Thermophoresis...but with the Ar going to...

Pretty straightforward question I hope. When the ray crosses into the material it will be refracted (ie. it's path changes direction). What is the explanation of this? All I have really been taught so far is that it does. I gather that it depends on the dielectric constant of a material but I...

Can anyone explain what is the cause of diamagnetism... to the extent i know is that the paired electron with opposite spin cancel out each other's magnetic moment... is there something more to this...? and on application of external magnetic filed why does it repel it... thanks for...

If it is not possible to tell the difference, then why should we conclude that something for which a cause is unknown is without a cause?

If temperature gradients cause wind in air, how about in zero gravity?? Hey guys, I'm aware that atmospheric temperature gradients causes changes in bouyancy so hot air goes up and cold air goes down and immediately fills in the 'void' the hot air left, thus causing wind. What about in...

I know the concept of diffraction of light, but not yet understood why light should bend passing the edges of objects ! I mean what makes it bend?

Hi, I'm a physics student but I have not done much astronomy/cosmology. I was sitting here thinking, and something struck me. This thought is only a couple of minutes old so it's not much more than half-arsed musings at this stage. However, I am curious about whether someone who knows what they...

I have always wondered if anyone has ever developed an understanding of why Back EMF happens? All I know is it happens when the the field inside of a transformer collapses at some low frequency during the collapse of the coil when the transistor shuts off creates a huge spike hundreds of...

Homework Statement Given F, b, and h, determine the angle θ which will cause the greatest strain. http://img844.imageshack.us/img844/5595/cusersjoshappdatalocalt.th.png The Attempt at a Solution I know to break it up into components so that I get Ma = F(bcosθ+hsinθ). But after that I'm at a...

Hello, while making my tea and watching the spoon inside the glass (with water), I start questioning myself what really is refraction. On class they just told me refraction is because light goes slower in a medium, so it bends according to Snell's Law. What is Snell's Law? Light bends to a...

I understand how a pressure differential caused by an altitude change can cause temporary pain, but can it actually cause a lasting infection? There are two suspected cases in my entourage.

My mother has suggested that I quit carrying my cellphone in my pocket, because having it sit there all day by my leg could lead to a tumor. I can't say how plausible this is, so what better place to ask than PF? Again, my question is whether merely carrying your phone in your pocket could...

Mass extinction as a result of oil spill. http://www.helium.com/items/1882339-doomsday-how-bp-gulf-disaster-may-have-triggered-a-world-killing-event" Any thoughts? Smells of crackpot to me.

What is the source of kinetic energy? If the Milky Way is moving toward the Virgo cluster at 600km/ sec, it has a kinetic energy of 4 e59 ergs. Second, take an electron "rotating" around a nucleus with a ionization energy of 15eV and then multiply by the number of electrons ,e79, for e68 ergs...

Let's say you are receiving photons from all over. The velocity of each photon coming to you is c. If you moved at velocity v compared to your initial inertial frame, without SR you would say that photons going the same direction as you are moving at c-v, while the photons going the opposite...

Hi, Lately I've been concerned about the Ohm's law J=\sigma E and the physical interpretation of this law depending on what is considered the cause and what the effect. More concretely, it is quite natural and intuitive for me the interpretation of this law in one direction: a electric field...

From what I have read: Tar causes cancer in road crews and smokers, gasoline causes leukemia in neighbors to gas stations and petroleum plants, benzene causes bladder cancer and leukemia in rubber workers - how about the BP bio-poisoning?

Hello! My name is Edward Solomon and I have found a very particular concept in classical physics to be more mystifying and puzzling than even more advanced topics covered in modern physics. This is the theory of "inertia." Although there is much literature covering the effects of inertia, I...

I was wondering what caused the big bang? The expansion would need some energy to start wouldn't it?

Hi all, In the attached image I have a cylinder shaped wheel with a air pocket embedded near its edge. The wheel has the same density as water and is fully submerged in a tank of water. Also the wheel is only free to spin about its center axis. If the wheel is rotated down the air pocket will...

I don't know what to say about this other than to wonder what this guy was thinking. :rolleyes: http://news.yahoo.com/s/ap/20100419/ap_on_re_mi_ea/ml_iran_earthquakes_promiscuity" I love the reaction though...

Hi, I believe the general notion is that gravity is an effect caused by the warping of spacetime. I've read that clocks are running faster in Satellites by about 50 micro seconds per day (or 2 micro seconds per hour) compared with on the Earth's surface. As one moves from the Satellite...