Observation Definition and 228 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. FallenApple

    B Does observation *Determine* the past?

    Say a photon was emitted from very far away such that it would take billions of years to reach us. According to Feynman's infinite paths, the photon travels every possible path on its way to reach us. The superposition of infinite trajectories collapses when it hits something solid, say an...
  2. Umrao

    SR: Does observation change when changing reference frame

    Homework Statement Special relativity: A rod traveling with the relativistic velocity of 0.866c moving towards a garage. The length of the rod is L, that of the garage is L/2. From the reference frame of the garage, we find the value of Lorentz factor = 2 we say that rod would fit inside garage...
  3. Andy_K

    I Twin Paradox - Observation at Turnaround Moment

    Dear All, I am doing the Special Relativity course at World Science U, and came across this question which I got wrong: When 100 nanoseconds have elapsed on traveling Gracie's watch, she immediately stops, turns around, and heads back toward George at the same speed of her outbound journey...
  4. T

    I How does observation affect reality

    In quantum physics, one can change a system just by observing it, such as wave function collapse and quantum Zeno effect. I don't quite get how observation affects them, unless we are interacting with them when observing them.
  5. B

    I Observation of photons from CMB by different observers

    If two observers on Earth in different locations around the globe, were both viewing the CMB with their equipment pointing at the same point in the sky, and charting the fluctuations in it, would they correspond or vary from each other greatly. In other words, if you made a graph of the CMB and...
  6. S

    I What happens when a particle observes itself during quantum tunneling?

    The QM is saying that a particle in some potential pattern will have a wavefunction that describes the probability to find the particle. And then it also said that observation will make wavefunction collapse into measured value. For example, the electron in an atom will be in one position after...
  7. Lord Crc

    Observation of laser pulse propagation in optical fibers

    Just wanted to share this, mainly because I really liked the videos (found in the supplementary section at the end). Moderators, feel free to move it to a more appropriate place. Observation of laser pulse propagation in optical fibers with a SPAD camera Recording processes and events that...
  8. P

    I How to know what proposal to write for observation?

    So, proposals are soon going to be accepted for the NASA's Chandra X-ray Observatory and the professor that I am currently working on asked us to come up with ideas for a proposal, they can be anything! However, because I am just starting research, I am not sure yet what I want to observe, but I...
  9. A

    B Calculate Speed of Relativistic Rocket by Observation

    Hi, here are image of situation. We have observer in point A. He have clock and know distance L between points B and C. He is observing rocket travel from point B to point C at speed near light speed. Can he calculate the speed of rocket using v = L / TimeA? In rocket at point B here are...
  10. J

    B Double Slit detectors question

    My question about the double slit experiment is this: why is it that nobody suspects that the detectors used to detect particles as they pass through the slits in the double slit experiment aren't causing some interference with the experiment which makes it seem as though they are acting like...
  11. Bill_W

    B Quantum Physics -Double Slit Delayed Observation

    Thanks in advance to all who reply. Forgive me if this naive, I am not scientifically inclined, but I am VERY curious. After re-watching a documentary on quantum physics, I have a "thought experiment" that I would like feedback on. Maybe this experiment (or something like it) has already been...
  12. lep11

    MATLAB Data Analysis: Observation Model Problem

    The observation model will be ##z=H\theta+v##, where ##z## is column vector containing the results, ##H## is the observation matrix, ##\theta## is the parameter vector and ##v## is a vector containing random additive noise. b.) In this case ##z##=[1 1 0; 1 0 1; 0 1 1; 1 1 1]*[##m_1## ##m_2##...
  13. Punit D

    I Time Dilation Observation: What Does Earth Observe?

    I'm wondering if anyone can answer this question for me. Suppose we send a spaceship to the moon at 299,792,457 m/s (1m/s less than c). That's 99.9999997% of the speed of light. Plugging the numbers into the time dilation formula, we get that the 1.2822 seconds that it takes for the spaceship...
  14. N

    I A quantum system under constant observation

    To start off I'd like to apologize ahead of time for the grammatical errors and lack of eloquence that are sure to follow, it's the middle of the night and my mind is wandering but my cognitive capacity to express my self is pretty low at this time. With that out of the way, I'd like to ask...
  15. Samia qureshi

    How does electrostatics explain the invisibility of quickly passing objects?

    If car passes very very very quickly in front of you, you will not be able to see it... We will not be able to observe it... As seeing is believing, So which proof we have that this car really existed and passed in front of us?I Think the concept of electrostatic isn't it?
  16. Bristlethorn

    Interesting topics for undergraduate astrophysics research?

    Starting in the fall of this year, I'm going to get to start my own year-long undergraduate research project. To summarize as briefly as possible: Resources Available: Our university has access to the SMARTS consortium's three telescopes: - 1.5m CHIRON telescope - 1.3m ANDICAM telescope...
  17. V

    I Observation of distances w.r.t. metric

    Hello. I don't know exactly if my question can be treated physically but so... Let us have a 3D space with non-constant metric. We are in the first region with a euclidian metric. ds^2=dx^2+dy^2+dz^2 So the distance between two points is got through pythagorean theorem Then near us we have the...
  18. O

    A "Observation" of Black Hole Merger

    Premise 1: From the frame of reference of the earth, observing a thing falling into a black hole (crossing the Schwarzschild radius) is impossible -> the thing is observed falling toward but never reaching the radius, i.e. the process takes an infinite amount of time. Premise 2: Observation...
  19. pioneerboy

    I What's Next for Astrogeology and Planetary Sciences?

    I dropped out of physics in college and have several career choices now for the near future being all vocational. In the far future I want to end up in planetary sciences again. So, I'll want to work again with planetesimals, dwarf planets, evolution of planets, their geology, and astrobiology...
  20. Chaitanya V

    B Atomic Structure: Theory vs Observation

    Does atom really looks and behaves like as that explained in quantum mechanical model? Or is it just a Mathematical Tool to express the observations? Is it like that that scientist were unable to find any clue about real atomic structure and just created a mathematical tools following the...
  21. Dadface

    Entangled states before observation.

    I think this is just a quickie. I'm interested in what is assumed about entangled photons/particles before they are observed. Is it correct to assume that the photons/particles exist in all possible states simultaneously? Thank you.
  22. F

    Observation and its role on objects/matter/particles

    As I understand it, in the double slit experiment electrons were found to exist in both wave and particle form depending on observation. The electron is a tiny speck of matter, and so does observation have the same effect on all matter? Max Planck said there is no matter as such. Is this because...
  23. J

    Axiom of QM is Observation... but

    It is said the axiom of QM is observation.. but if observation is secondary effect of more primary dynamics that don't involve observations.. could it still be called QM, and what's it supposed to be called? In other words. Say QM is emergent from a deeper reality.. and we are to study the...
  24. W

    Double slit experiment observation on and off

    Might I be so bold as to ask a question about the "double slit experiment". Was wondering...have scientist ever considered...turning the observation on and off...? Is it even possible...? Experiment says...when observed...particles react one way...and when not observed...they react a different...
  25. C

    What Are Filtering Type Observations in Quantum Mechanics?

    I read that state preparation is simply measuring and confirming the system. Filtering type observation is when the observation doesn't destroy the system. But googling doesn't produce the extra words "Filtering type observation".. why is these words only in physicsforums.. what are the other...
  26. Rob Haskell

    Accounting for time passed in our observation of the universe

    Greetings - We speak of astronomical objects as being x number of light years away, which is also a statement about the age of the data. So our knowledge of M83, for example, is about 15 million years old, etc, etc. I'm just wondering why there never seems to be any attempt to move this...
  27. GiantSheeps

    Stargazing Remote Controlling Truss Dobsonian Telescope?

    Is it possible to rig a Truss Dobsonian telescope like this one so that you can control it remotely from inside of a building while the telescope itself is on the roof of the building? Then is it possible to attach some sort of adapter to the telescope that would allow you to hook up a camera...
  28. Green dwarf

    Quantum observation of black hole?

    [Moderator's note: this discussion has been spun off from another thread.] This is probably a silly idea, but I haven't got any reputation to preserve, so I'll mention it anyway. My very limited (and probably very wrong) understanding of quantum theory tells me that until something is...
  29. S

    Comparing Radio and X-Ray Galaxies: Redshift vs. Emission Mechanism

    Are all the radio galaxies in the (approximarely) same distance from us? And is the reciveing frequency from all of them in radio band? I am wondering whether the difference between a radio and x-ray galaxy is their redshift or their emission mechanism ?
  30. S

    Understanding Observing Frequency and Its Significance in Radio Astronomy

    I believe that when we say that this is radio telescope, it means that reciving frequency of it is in radio band. And also it means an observed object by that is in a particular redshift that its emission has a particular frequency that when receives us, is in radio band. Am I right? For ex. We...
  31. ComaBerenices

    Is Time an Illusion? Platonic Idealism & Human Observation

    Now, we humans observe time to be absolute and always progressing into entropy. However, mathematically it really just seems like a axis which helps determine energy and entropy at points along the grid. I guess what I'm curious about is if there is a bias as to how time progresses, I mean...
  32. quantumfunction

    I Entanglement Swapping and measurement vs. observation

    I think entanglement swapping shows the difference between measurement and observation. A measurement isn't as important as observation at least to subatomic particles. Here's some key points...
  33. Feeble Wonk

    Macroscopic observation of interference?

    I suppose a related question is in regard to the fundamental nature of quantum superposition. Does any system in superposition "necessarily" demonstrate interference on a macroscopic scale?
  34. M

    High resolution observations of dark matter?

    Are there any high resolution observations of the gravitational lensing by dark matter, good enough to determine if dark matter is clumped or spread out at small scales?
  35. L

    An observation about relativistic space travel....

    I suppose I am not the first to notice this, but if you are going at say, 0.999c you will have shrunk by a factor of about 20 and everything else on the craft. Suppose the spacecraft is 2000 meters long, at 0.999c it will shrink to about 100 meters long. So suppose a person 2 meters tall...
  36. diogenesNY

    Possible observation of Pop III stars....? -NY Times article

    I thought this might be of interest: NY Times article on evidence of pop III stars. diogenesNY -------------------------- New York Times - June 17, 2015 Astronomers Report Finding Earliest Stars That Enriched Cosmos By DENNIS OVERBYEJUNE 17, 2015 Astronomers said on Wednesday that they had...
  37. E

    Star Observation Calculation Homework

    Homework Statement The intensity of the Sun's radiation is about 1380 Wm-2 at Earth's distance, 1.5x1011m. Earth absorbs this radiation as a black body, and radiates its own energy back into space. a) How much Energy per second falls on the Earth's surface? (Diameter of Earth = 12800km) b)...
  38. Joshua McAnaney

    An Observation And A Question -- Why does metal arc in a microwave oven?

    So, I'm new around here and I'm not entirely sure if this is in the right section, but today I noticed something which I found thought-provoking. Before I go into this, I should point out that I'm 16, so all of my physics knowledge above high-school level is entirely self-taught, so I still have...
  39. D

    "silly" question - Neutrino observation

    Hello. Probably a stupid question, but hey why not. Since Neutrino's do not interact with electromagnetic fields, but cosmic rays and other particles (that would overwhelm a neutrino signal if observed in an environment not at least partially shielded from their signals as at SNO etc) DO...
  40. M

    How Does Light-Matter Interaction Challenge Classical and Quantum Views?

    I have just started reading about a classical electromagnetic treatment of light-matter interaction (beginning with dispersion relations, and then moving on to the standard phenomena - reflection, refraction, etc.). The discussion begins with a forewarning that light is not 'continuous' as the...
  41. ant0n

    How would observation of the state of qubits affect them?

    Firstly, I apologise for any lack of understanding, incorrect assumptions or misinterpretations of the very little I know about physics, quantum mechanics & quantum computing. I am not an academic, scientist or mathematician, but a software engineer with an interest in quantum computing and...
  42. C

    Black Hole Time Dilation And Observation Of Accretion

    Hello. If time is infinitely dilated at the edge of the EH, how do we observe accretion?
  43. julianwitkowski

    Time Dilation Effects on Observer Perception

    If an observer was traveling with a Lorentz factor that would make that observers time slower than someone's on Earth, what would that observer see watching a live video feed, or if it was possible to observe Earth with a telescope, and vice versa? I understand that either party would only see...
  44. J

    Direction of a photon is fixed upon creation or observation?

    My question is a little more broad than I could make clear in the title but here goes. First of all, to be clear, am I correct in understanding that light behaves in precisely the same way as an electron in the sense that there exists a wave function which evolves according the Schrodinger...
  45. T

    Baffled by observation -- 3 lights in the night sky

    Hi! :) This is my first message here. The reason I joined this forum is because there are some knowledgeable people here who might be able to shed some light on an observation that I cannot explain. It happened during the night of July 28, 2013, at around midnight, and it still keeps me...
  46. Superposed_Cat

    Entanglement, why are the spins decided on observation?

    Hi all, I'm not really seeing why entanglement is such a big deal, if total spin was 0 and the particles it creates can only have spin 1/2 and spin +1/2 then if one is down the other must be up, so they have spins designated at birth so to speak, what makes us think they don't have spin till...
  47. K

    Alcubierre Warp Bubbles: Observation & Travel Questions

    I've been reading a lot of hype about Sonny White and his attempts to look for Alcubierre warp bubbles. If objects do in fact non-locally travel at de facto superluminal speeds, how can these objects be observed to be traveling at such speeds? Wouldn't the observer just see the light outside of...
  48. Marc Nash

    Understanding the Dual Nature of Light: A Science Layman's Questions

    As a writer, light is as crucial as it is to physicists. But I'm struggling with some conceptual understanding surrounding light. If you could supply any answers to this science layman I would be very grateful. 1) Without light there is no way of observing and measuring. So light is both itself...
  49. Jonathan Scott

    An observation on potential energy in GR

    There are various different ways to try to add up the effective total mass of a configuration of masses in GR in such a way that it comes out to be equal to the total of the source mass as measured locally minus the gravitational binding energy. One of these is for example the Komar mass, which...
  50. K

    Most probable value given observation

    Suppose I have observed ##Z = 3##, where ##Z = X + Y##, where ##X \sim N(0,9), Y \sim N(0,4)##. How would I find the most probable value of ##X## that would have given me ##Z = 3##? My attempt at a solution: I was given that ##X## and ##Y## are independent, so that means ##Z \sim N(0+0, 9+4) =...
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