Observed Definition and 195 Threads

Observation is the active acquisition of information from a primary source. In living beings, observation employs the senses. In science, observation can also involve the perception and recording of data via the use of scientific instruments. The term may also refer to any data collected during the scientific activity. Observations can be qualitative, that is, only the absence or presence of a property is noted, or quantitative if a numerical value is attached to the observed phenomenon by counting or measuring.

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  1. C

    First magnetic phenomenon observed on the Sun

    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...
  2. D

    HOW can entanglement be observed experimentally?

    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...
  3. J

    Does the Quantum Zeno Effect Contradict the Heisenberg Uncertainty Principle?

    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?
  4. edguy99

    Observed intensity of Persistent Lines of Neutral Hydrogen

    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...
  5. S

    Speed of two spaceships relative to each other observed by an earth observer

    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...
  6. C

    Observed planets in binary star L4 or L5?

    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...
  7. U

    What is the observed precession of Mercury?

    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...
  8. A

    Why does rain appears to be inclined when observed from a moving car?

    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...
  9. F

    What does it means to say two events are simultaneously observed?

    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...
  10. StevieTNZ

    Probabilities & Observed Reality

    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...
  11. C

    I've observed that by putting great effort into learning concepts

    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...
  12. A

    Colourful moon dog observed, or what?

    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...
  13. O

    2D Kinematics; Flying Saucer observed with two velocities

    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...
  14. T

    Newbie question: Long trips and observed time

    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...
  15. B

    Any papers out that show the observed z vs. t?

    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...
  16. N

    Photons observed on photographic plate - but not in eyes? Why?

    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?
  17. O

    Is it possible for the arrow of time to be observed in reverse?

    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...
  18. A

    How Do You Calculate Observed Angular Velocity from a Reference Frame?

    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...
  19. D

    Pair production: Has it been observed experimentally?

    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...
  20. H

    Photon observed to be behaving as a particle

    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...
  21. E

    Reality exists when observed, but who is the observer?

    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...
  22. T

    Doppler Effect Observed Frequency Under Special Conditions

    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 )/(...
  23. D

    What Determines the Speed of a Spacecraft in Special Relativity?

    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...
  24. F

    How does Changing Salt Bridge Solution affect observed voltages?

    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...
  25. Borek

    The Potential of Antimatter for Nuclear Reactor Control

    http://arxiv.org/abs/1103.3312
  26. H

    What would actually be observed during Lorentz contraction?

    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...
  27. rcgldr

    Gravity effect on observed speed of light

    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...
  28. M

    Can the speed of light be observed to be faster than c?

    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...
  29. R

    13.1 billion light years object observed.

    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...
  30. C

    When particles are not being observed do they still exist?

    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...
  31. A

    Interference pattern observed half-way into the formation

    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...
  32. T

    Experimentally observed properties of liquid 3He as a superfluid

    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...
  33. L

    Where Can I Find Raw Data for Galactic Curve Velocities?

    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...
  34. W

    Special relativity clocks observed from two frames

    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...
  35. P

    Analog of Hawking Radiation Observed?

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

    New two-particle correlations observed in the CMS detector at the LHC

    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
  37. S

    Find speed of quasar from observed and actual wavelength readings

    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...
  38. M

    Calculate difference between observed frequency and original frequency

    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...
  39. W

    Exploring the Observed Flow of Galaxies in the Expanding Universe

    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
  40. M

    How is quantum entanglement observed?

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

    Wayward Stars: Has Ejection Ever Been Observed?

    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...
  42. M

    How Does Observed Superposition Impact Interpretations of Quantum Mechanics?

    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...
  43. U

    How much of space has humanity observed?

    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...
  44. T

    Observed speed of light [actually about relativistic velocity addition]

    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...
  45. M

    Matter mechanics: Ideal & observed stress

    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...
  46. R

    How is broken symmetry really observed?

    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.
  47. X

    Micron sized object observed in quantum state

    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...
  48. P

    What's the most distant observed star which is not a supernova or quasar?

    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?
  49. X

    Gravitational force on observed particle?

    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...
  50. J

    Has evolution actually been observed?

    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?
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