Observed Definition and 195 Threads

I am currently doing a bit of research into the history of our understanding of the solar magnetic field. It is quite interesting. As I understand it, sunspots, which were observed at least as early as the time of Aristotle, were the first solar magnetic phenomenon to be observed. Can...

hi all i have two questions. 1. Quantum entanglement is observed experimentally. But how can that be. Does not Quantum decoherence effect it from being observed? 2.The general notion is that M String theory if proven is theory of everything. But without explaining entanglement how does it...

in q zeno effect, measuring, or observing a particle will effect its outcome. however, its been said on this forum that the hup is there whether we observe it or not. contradiction?

The site http://physics.nist.gov/PhysRefData/Handbook/Tables/hydrogentable3.htm shows the intensity of various photon energy values from hydrogen. I was not able to see how this intensity was observed (ie. was it from a specific experiment, or does one simply look at the sun and count photons...

Edit. I think the topic is misinformative and I don't know how to change it. Hey I have to translate this into english so bear with me. Two spaceships are approaching Earth from two directions along the x-axis. Earth observer(EO) calculates their speeds to be 0,8c each. Calculate at what...

It seems to me, from my understanding of the Lagrange points, that a binary system with the appropriate mass ratio between stars could support planets in the L4 and L5 Lagrange points (I've encountered this, actually, in science fiction; Larry Niven put such a planet in the Procyon system for...

The precession of Mercury is presented as one of the threshold moments for general relativity. Are there any publicly available summaries of the classical anomaly? Most refer to a 1947 paper that uses an outdated reference frame. Clemence, G. M. (1947). "The Relativity Effect in Planetary...

Why does rain appears to be inclined when observed from inside of a moving car? Assume that the rain is straight. Then the person in the moving car sees that rain is inclined and a person standing on the road sees the straight rain. Is my observation correct? When I first saw this I...

This is not homework problem, but I am using a problem from Elementary Modern Physics by Weidner and Sells as context for my question. It reads "A star is moving away from the Earth at 0.60c as measured in inertial system S, at rest with respect to the earth. At time t=0, when the star is 1.0...

Hi there, I'm thinking of an experimental set-up that incorporates cameras behind a double-slit screen. The cameras will take a picture if a particle goes through the applicable slit. For me to know which slit it goes through, I need to check the camera to see if its taken a picture. For...

I've observed that by putting great effort into learning concepts which initially seem incomprehensible or very difficult to conceptualise, even if it may at first appear like I made little or no progress, I usually end up with enhanced cognitive abilities which extend beyond the concepts I was...

Colourful moon dog observed, or what?? Look at the following picture, taken 12/9 by Thomas Sannes: http://www.storm.no/nyheter/fotograferte-sjeldent-vaerfenomen-3583707.html He sent the picture to meteorologists, and they made their bet that this rainbow-coloured bright spot on the night...

Homework Statement A flying saucer maneuvering with constant acceleration is observed with the positions and velocities shown below: http://imgur.com/gq1g0 What is the saucer's acceleration? *note: I created the image in paint and I did forget to label the vectors. The one starting...

Hello All, I hope my question isn't too simplistic for this forum. I've been giving my kids this illustration for a couple years, and have begun to doubt my story a bit. Hoping someone here might be able to clarify for me. It's simple really, here's the setup: *You're going to a star 10...

I know the constant ΛCDM model predicts the expansion factor a (= 1/[1+z] providing we impose the condition a = 1 now) to be of the form (sinh bt)2/3 for recent times. Are there any papers that determine either a(t) or z(t) from the supernova data, showing error bars? I think that the present...

Hey, We can observe the build up of photons on a photographic plate, but we can't observe this build up with our bare eyes. i.e. without needing a photographic plate - just by looking like how we look right now. how come?

I know that in general the arrow of time does not itself reverse but is it possible for there to exist 'observers' in our universe that see its progression from, what we think as, finish to start? I just read http://arxiv.org/pdf/hep-th/0611088v3" by Brett McInnes so I understand why the...

Homework Statement Determine the observed angular velocity from the origin of the reference frame for an object shown in the figure. The observed angular velocity is defined as the rate with which the observed direction on the object (measured in radians) changes in time. Hint: The observed...

I was reading about electron-positron annihilation and I got to the part where it says that this is a reversible process, meaning that an electron and a positron could be created from photons. About this reverse process the article says "In nuclear physics, this occurs when a high-energy photon...

I thought you might find this interesting. I'm not sure it fundamentally changes any interpretation issues but it does have some intriguing possibilities both for future experiments and the philosophical issues, particularly those who favour particle models. Full article here...

Hi, Reading about quantum mechanics, the probability wave is so that a particle can be everywhere. But when observed, it's probability wave collapses and the particle has to take a definite state. The example were given for Schrödinger's cat, which is either alive or dead only after we...

vw= Velocity of Wave vm= Velocity of Wave Source fw= Frequency of the Wave fd= Frequency of the Wave relative to Detector as Wave Source is also moving q= Infinity For the wave frequency detected by a detector at rest as the wave source* is moving towards it, there is: fd=( vwfw )/(...

Homework Statement Usually in physics problem on special relativity, the state that this particular spaceship is traveling at, say, 0.6c. Question is, where does this 0.6c come from? If the speedometer in the cockpit reads 0.6c, does it mean that the observer will look and think that it...

Homework Statement In a lab in which many half-cells are constructed, one of which contains Zn2+, the original salt bridge solution is Potassium nitrate. Suppose we needed to change this solution to Zinc nitrate. What would be the effect on the observed cell potentials? Homework Equations...

http://arxiv.org/abs/1103.3312

Greetings everyone, I understand the derivation of the Lorentz transformations, and have not had trouble applying the concepts and the math to most elementary SR problems. However, something occurred to me recently which I have been unable to resolve. Let’s say there are two tennis balls...

An observer (in zero gravity) witnesses two parallel but widely separated beams of light that are transmited at the same time. One of the beams experiences zero gravity. The other beam travels between two massive objects with a very strong gravitational field, but arranged so that the beam...

Homework Statement Two parties (A and B) are signing a treaty at opposite ends of a 40.0meter table. The two parties and very suspicious so it is important for the two to sign the documents at the same time. This is arranged when the light from a light bulb at the center of the table reaches...

Last year Astronomers observed a self-destructing star 13.1 billion light years away. Happening only 630 million years after the big bang. While it is amazing that we are able to observe objects that far away, questions arose. Now for a moment, let's imagine our universe in it's 3 axis (y, x...

I was hoping someone could explain, in terms I can understand, the movement of particles. Clearly I am not a scientist, but I just want to fully understand the idea that when particles are not being observed they either no longer exist or just do as they please. The example I was given is that...

We know that the interference pattern forms even when photons (or electrons etc.) are sent one at a time. The photons only land on the fringe parts of the screen and not the dark part - as if directed by some underlying information about where they are supposed to go. So far so good...

Hey everyone, I'm currently taking a thermal physics course and have been assigned a research paper about the thermodynamically arguable aspects of experimentally observed properties of the 3He superfluid. I have been searching for many different sources but have only found a few worthwhile...

Hi. I have google'd for awhile but cannot seem to find this information (velocities of stars in the galactic curve). I need to work with the raw data observed before calculating the doppler shift and subtracting the Earth and sun radial movement out of it. I need the transverse velocities as...

Homework Statement Observers S and S' stand at the origins of their respective frames, which are moving relative to each other with a speed of .6c. Each has a standard clock, which, as usual, they set to zero when the two origins coincide. Observer S keeps the S' clock visually in sight...

Didn't see a post about this yet. http://arxiv.org/abs/1009.4634

http://cms.web.cern.ch/cms/News/2010/QCD-10-002/ http://motls.blogspot.com/2010/09/lhc-probably-sees-new-shocking-physics.html http://cms.web.cern.ch/cms/News/2010/QCD-10-002/CERN_seminar_QCD-10-002_introduction.pdf pg 14

1. Astronomers on Earth observe a feature at 442 nm in the spectrum of a distant quasar. However, it is known that this feature corresponds to 581 nm in the rest frame of the quasar. Calculate the speed of the quasar. Enter your answer as a fraction of the speed of light, positive if the quasar...

Homework Statement A radar trap operates at a frequency of f = 10GHz. The speed of microwaves is 3.0x10^8m/s. The microwave beam is aimed at a car approaching at 20m/s. a) calculate difference between observed frequency and original frequency. b) the car becomes the moving source at...

Anybody out there with info? What part of the expandable universe have the galaxys been observed to be flowing to a pecticular direction. Been looking for information site on topic. Thanks

Any measurement device used to witness the phenomenom seems like it would disrupt quantum entanglement. How do scientists manage to observe it?

hey everyone, I have one question. Has it ever been heard of, for a star moving at higher velocities, to be 'ejected'?. Especially if its on the fringes of the galaxy? Or if two galaxies where to collide, wouldn't it be plausible, for stars and be swept away into empy space outside of any...

Since there have now been directly observed superpositions in laboratory experiments, meaning of course that superposition is not an interpretative issue but an observed aspect of nature, does this have any consequences for certain interpretations of QM? I particurlarly had in mind hidden...

I vaguely remember reading somewhere something that, in its entirety, human civilization, with all its telescopes and radio dishes and cameras, has only "mapped" (seen and documented) about 3% of the (observable) universe. Can anybody make any comments on the reality of this? Is it even...

I apologize if this is a repost, my original post didn't seem to take. If you accelerate a particle to 99% the speed of light and accelerate another particle to 99% the speed of light directly into the path of the first would this not create the observed effect from either particle that the...

So I understnad that typical solid state bonds brake at stress of up to 20%. Why though, in reality, do we never observe this? Is it due to inherent inhomogenieties? What kinds of mechanisms & structures would cause this observed strain in tensile and shear cases? Could one observe ideal...

Hello, Now that there's only one week left until the LHC starts working on the collisions, I think it's a good idea for me to ease my mind and ask how will they observe superparticles and discern them from the SM particles.

In a following link: http://physicsworld.com/cws/article/news/42019 authors claim to design a 40 micron sized resonator which they were able to set into a superposition of states. Should this be true, I find it fascinating and a new, fruitful way to explore quantum-classical border. Any...

I hear that large telescopes can resolve the Andromeda galaxy into individual stars. Is it possible to do the same for galaxies outside our local group? Also, have we observed any stars which sit in deep inter-galactic space, far from any galaxies?

Is there any experimental difference in gravitational force for a non-observed particle versus an observed particle in a gravitational field? Basically my question is if they fall with the same acceleration? The observed particle is observed the entire fall, but both the observed and the...

I know that it has been 'proven', but my question is, has it actually been observed by somebody? Yes, we can see the similarities between different subspecies and species but that alone is not proof that they evolved from each other. Has anyone actually seen it happen?