Experiment Definition and 1000 Threads

An experiment is a procedure carried out to support or refute a hypothesis. Experiments provide insight into cause-and-effect by demonstrating what outcome occurs when a particular factor is manipulated. Experiments vary greatly in goal and scale, but always rely on repeatable procedure and logical analysis of the results. There also exists natural experimental studies.
A child may carry out basic experiments to understand how things fall to the ground, while teams of scientists may take years of systematic investigation to advance their understanding of a phenomenon. Experiments and other types of hands-on activities are very important to student learning in the science classroom. Experiments can raise test scores and help a student become more engaged and interested in the material they are learning, especially when used over time. Experiments can vary from personal and informal natural comparisons (e.g. tasting a range of chocolates to find a favorite), to highly controlled (e.g. tests requiring complex apparatus overseen by many scientists that hope to discover information about subatomic particles). Uses of experiments vary considerably between the natural and human sciences.
Experiments typically include controls, which are designed to minimize the effects of variables other than the single independent variable. This increases the reliability of the results, often through a comparison between control measurements and the other measurements. Scientific controls are a part of the scientific method. Ideally, all variables in an experiment are controlled (accounted for by the control measurements) and none are uncontrolled. In such an experiment, if all controls work as expected, it is possible to conclude that the experiment works as intended, and that results are due to the effect of the tested variables.

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  1. K_Physics

    Relative Intensity of Various Light Sources - Lab Experiment

    Homework Statement I've linked my data table down below. My problem is the relative intensity column. From the table, the units of relative intensity are w/m/s. I'm assuming this is power/velocity, where velocity is the speed of light. However, nowhere in the lab manual did it mention the...
  2. B

    I Concerning concioussnes and the double slit experiment.

    Hello there, I have a question about the double-slit experiment and conscioussnes. Excuse me if I don't formulate things right and might come over as a total fool for asking this (English is not my native language and i don't study physics). I just saw this video: <Moderator's note: link...
  3. I

    Limitations of Young's double slit experiment

    Homework Statement From a procedure standpoint, our experiment consisted of a laser pointer on a retort stand with a holder, shining through a piece of sheet with slit measurements (I believe it's acetate) and measuring the height of the maxima on a whiteboard. What could be improved with this...
  4. I

    B What are some limitations to Young's Double Slit Experiment?

    From a procedure standpoint, our experiment consisted of a laser pointer on a retort stand with a holder, shining through a piece of sheet with slit measurements (I believe it's acetate) and measuring the height of the maxima on a whiteboard. What could be improved with this experiment?
  5. I

    B Slit Distance - Young's Double Slit Experiment

    I understand Young's Double Slit Experiment, which basically consists of pointing a laser through two slits and seeing the maxima with different brightness, caused by constructive and destructive interference respectively. Through the experiment, I know that increasing the distance between the...
  6. R

    B Some very basic questions around the double slit experiment

    I have a few basic questions about the double slit experiment and was hoping someone might be able to answer them. 1) How far apart from each other would have I have to make the slits so effectively no detection took place? E.g. is there a limit to how far the wave function can spread and a...
  7. C

    B How Does Detector Placement Affect Ratios in the Double Slit Experiment?

    Here is a setup that only uses fixed detectors. Will the ratio between the number of detections at D0 and the sum of the numbers detected on D1 and D2 be close to 1? For this question instead of the coincidence counter, 3 simple counters are needed. Also the detectors D1 and D2 need some lenses...
  8. Mason Smith

    Millikan's Oil-Drop Experiment: Is my reasoning correct?

    Homework Statement Show that the electric field needed to make the rise time of the oil drop equal to the its field free time is ε = (2mg)/q Homework Equations Newton's second law F = ma The force of gravity FG = mg, where g = 9.8 ms-2 The force of buoyancy Fb = bv The force of an electric...
  9. J

    I Find a calculation of Schrödinger's cat experiment?

    Hello, does someone know where to find a calculation of Schrödinger's cat experiment? (like psi(cat)=|dead> + |alive>...)
  10. Alexander350

    Significant figures in a results table

    Homework Statement Basically there is a results table for the time taken for 20 oscillations. Three examples are 9.90, 11.16 and 12.68. I need to work out the time period to the correct number of significant figures. Homework EquationsThe Attempt at a Solution I divide by 20 to get the time...
  11. arpon

    I Experiment: Spin Rotation Operator

    How do we experimentally apply the operator ## \exp{\left(-i\phi\frac{ S_z}{\hbar}\right)}## on a quantum mechanical system? (Here ##S_z## is the spin angular momentum operator along the z-axis) For example, on a beam of electrons?
  12. C

    I Michelson Morley experiment: relativistic explanation

    I don't uderstand how, using special relativity theory (time dilatation and length contraction), one can explain why in the Michelson interferometer there is no delay between the two rays in the reference frame where the interferometer is moving. Consider the picture ##2.## Setting...
  13. K

    B Photon detection in the EPR experiment

    In the photon version of the EPR experiment, how is the final polarization state of the photon detected? I have read a number of high level descriptions of the EPR experiment, but I am having trouble with understanding the detection part. Here is my understanding, please correct me where I am...
  14. Buzz Bloom

    I Models of accretion disc emissions contradicted by experiment

    Ref: http://www.spaceref.com/news/viewpr.html?pid=51416 I would be very interested to see comments from knowledgeable people about this. My impression is that this is one more example of a need to remain at least somewhat skeptical about theoretical models that have not yet been validated by...
  15. J

    Why does my experimental value of g differ greatly?

    Homework Statement Hi, I did an experiment where I launched a soccer ball into projectile motion with my hand and took a video the situation. I uploaded it into the Tracker software to analyze it. The tracker software gave me a x-t graph, a y-t graph, and a y-x graph. From the y-t graph...
  16. U

    I Local, non-realistic description of the EPR-Bohm experiment

    I propose for your consideration the following version of this experiment: We have a source, S that produce pairs of spin 1/2 entangled particles and two detectors, A and B that measure the spin of those particles. The detectors are oriented on the same direction, say X and they are fixed. As...
  17. D

    I Einstein's light clock thought experiment

    I'm an engineer who has an amateur interest in physics. I have been reading about Einsteins light clock experiment. I understand the principal that when a light clock on a train etc is moving relative to a standing still observer then the light must travel a longer distance per tick. given that...
  18. P

    I Proposal for a peculiar double-slit experiment

    Hi to all who might respond, Consider the 'peculiar' double-slit setup below. There is a double-slit configuration such that the two slits are never open at the same time. That is: whenever the top slit is open for a certain interval, Ts, the bottom slit is closed for the same interval and vice...
  19. J

    Diamagnetism experiment with copper/lead

    I'm new to the concept of diamagnetism, but it seems very fascinating, and I'd like to try a simple experiment. Say I wanted to repel a small piece of lead (or copper, both are readily available to me) about 3.5 grams, how strong of a magnet would I need? Could I just use small neodymium magnets...
  20. S

    I Zeeman effect after a Stern-Gerlach experiment

    Let's say you take a beam of particles and pass it through a Stern Gerlach apparatus and you select one of the outgoing beams, therefore collapsing the wavefunction to certain values of orbital angular momentum and spin angular momentum. If you performed the Zeeman experiment on that beam, I'm...
  21. H

    Prove Lorentz-Fitzgerald Contraction w/ Michelson-Morley Experiment at Any Angle

    I find this question rather difficult! Q1. I take Fig 1-11 to be the laboratory frame and ##v## to be the velocity of the ether wind. Since Lorentz length contraction occurs only horizontally, the right mirror should be further to the right horizontally in the ether frame. This makes the angle...
  22. J

    Speed of Light Thought Experiment

    A thought experiment about the speed of light. Say I build a 600,000 km long tube around the circumference of the Earth at the Equator. The tube's inner diameter is constant at 54.4505 mm. A snooker ball is perfectly manufactured to its lowest tolerance by a special new machine. Each one is...
  23. A

    A Speed of Gravitational Waves confirmed by Experiment?

    It seems that with the 2016 LIGO and VIRGO confirmation of the gravitational chirp that we have also experimental confirmation that the speed is indeed the speed of light. True? https://en.wikipedia.org/wiki/First_observation_of_gravitational_waves#Direct_observation
  24. ohwilleke

    I Is the new 3.0 TeV bump at ATLAS a fluke?

    The ATLAS experiment has seen a bump that could be a new particle at a mass of 3.0 TeV/c^2 with a local significance of more than three sigma, and a global significance of a bit more than two sigma in Run-2 data looking at decays of qqbb states to a W or Z boson and a Higgs boson. It is...
  25. T

    How does this experiment show that the future affects the past

    https://www.sciencedaily.com/releases/2015/02/150209083011.htm All I got out of the experiment is that the future measurements makes the measurements in the past more accurate. The future does not affect the past. Please correct my errors if any.
  26. V

    Experiment to measure EM waves

    Okay, let me prelude this by saying I only have an -EXTREMELY- limited understanding of classical physics, and zero knowledge of quantum mechanics. This is really just my asking a few questions in regards to an idea I had for an experiment, and what would be a good and accurate way to...
  27. K

    I Deep Underground Neutrino Experiment proton decay

    is there a reason that Deep Underground Neutrino Experiment which uses 70, 000 tons of liquid Argon doesn't also do double duty work as a proton decay experiment? Argon has plenty of protons and 70, 0000 tons is a lot of material to work with it costs several billion dollars so why not use...
  28. N

    Experiment - Flux, Irradiance, wavelength from Temperature

    In my experimental setup I have a purpose built small aluminium tube that has a black layer on the inside to mimic a blackbody. The tube is heated so the inside emits as a blackbody. A separate temperature sensor attached to the tube gives the temperature of the tube. I have a thermopile...
  29. B

    B Double-slit experiment observed by split brain

    Hello all, Does anybody here know whether the double-slit experiment has been conducted with a split brain patient as observer?
  30. A

    Is my Cyclette Generating Enough Power at Resistance Level 4?

    Hi all! I have a cyclette with 8 resistance levels set magnetically using a knob (a magnet is moved near the rotating disk thereby increasing its rotating resistance). The distance from the pedal to the center is 0.165 m. At resistance level 4, if I put a weight greater than or equal to 0.750...
  31. Wrichik Basu

    B Question in Franck and Hertz Experiment

    My book gives the following graph for current vs accelerating potential for Franck and Hertz experiment (used to prove existence of discrete energy levels in atoms) using Mercury vapours in the tube: The book then writes: "Actually, atoms have more than one excitation potential and also an...
  32. nomadreid

    Newtonian vacuum: what to call it in thought experiment

    Suppose you wanted a thought experiment about a variation on the vacuum (i.e., the spatial slice of spacetime) in which the quantum effects were absent or negligible, and the vacuum energy was zero . What would you call it? You can't call it the vacuum, because this Newtonian version of the...
  33. T

    B Double slit experiment question

    In the double slit experiment does the screen and the cardboard with the slits count as an observer since the electron interacted with them?
  34. T

    I Delayed choice experiment affecting the past

    I heard many people saying that the delayed choice experiment means that future events can affect the past. I doubt it as I believe that the wavefunction of the particle collapses as soon as a measurement is made. It does not matter where the detector is placed. As long as there is a detector...
  35. ChrisisC

    Laser and Mirror Thought Experiment

    I have a thought experiment that i need a answer to. In my experiment, I am in a bathroom with a mirror along one wall. I also have a laser that emits a single file line of photons. The laser is attached to the ceiling and emits a line of photons parallel to the mirror. What property of light...
  36. H

    I One by one photon delay in double slit experiment

    In a 'one photon at a time' double slit experiment, does the interference pattern still emerges if the time delay between individual photon emissions is increased to minutes or even hours?
  37. J

    Experiment Investigating Newton's 2nd Law

    Homework Statement We were given two methods to look into Newton's 2nd Law and evaluate them by looking at where sources of error may have come from. They both involved accelerating a car across a table. A plastic track was used to guide the car along a straight path to make sure it went...
  38. DaveC426913

    B Hypothetical ring world thought experiment

    I know this won't work, I'm having trouble explaining why to someone who thinks it will. Make a ring around a planet. Give it low walls. Fire countless pellets at hypersonic speeds around the inside of the ring. The pellets are moving at super-orbital speed, pushing the ring outward, making it...
  39. E

    Experimenting with Windings: Maximum Voltage Output?

    I attach an image of something I am experimenting with. The picture itself (and added text) should be self-explanatory. 1) Which way should my windings (clockwise or counter-clockwise) go around P1; P2; P3 & P4 for maximum voltage (V) ? [ 1 Ø ] [ 1 x single enamelled copper conductor ] [...
  40. Pushoam

    I How Does the Michelson-Morley Experiment Challenge Classical Physics?

    Relativity, Resnick Here, for calculating t2 , w.r.t. ether frame, light is moving along the triangular path as shown in Fig. 1.7 with speed c. w.r.t. interferometer frame, light is moving along the straight path with speed c##\hat y## - v ##\hat x## while going up and with speed -c##\hat y##...
  41. D

    Electroscope experiment in vacuum

    Hi I am running the electroscope experiment in vacuum. This is shown in (a) in the uploaded figure . Once the aluminum leafs are charged the chamber is pump down (b). As soon the pressure decrease low enough (around relative pressure of 30 inHg) the leafs collapse to each other abruptly. Here...
  42. YZEDY1one

    I Thought experiment- Dropping a rope into a Black hole

    Hi, Physics Forum! I've been wondering what would happen in the following thought experiment. I am not physicist and may have made some incorrect assumptions. Please explain if any of these assumptions are wrong. What would happen if you threw a piece of (very long and strong) rope into a...
  43. Andy_K

    B Double Slit Experiment: Timing & Reflection Interference

    Dear All, I have a couple questions on the double slit experiment I hope you can help shed some light (or photons) on. =) Arrival Timing of Photons In a normal double-slit experiment like the above setup, do photons always arrive at the detector at a constant speed (basically, speed of light)...
  44. Steven Ellet

    I Build Your Own Quantum Entanglement Experiment?

    Came across a pair of websites claiming to be DIY Quantum Entanglement Experiment. Problem is, I don't know how realistic it is. Essentially, is this real, or am I being taken for a fool? Part 1...
  45. K

    Why does the horizontal distance L contract in the Michelson-Morley experiment?

    Homework Statement Lorentz suggested that L parallel shortens the amount: And inserting it back cancels the time difference: $$\frac{2L/C}{\sqrt{1-u^2/c^2}}>\frac{2L/C}{1-u^2/c^2}~\rightarrow~t_1+t_2<2t_3$$ Logic says i have to increase L in order to increase t1+t2 so it will equal 2t3...
  46. dholbach

    Can a cathode ray tube be made from a light bulb?

    Light bulbs and cathode ray tubes are structurally similar in some respects. For example, both contain a filament -- in the light bulb, the filament heats up to produce light, while in a cathode ray tube, the filament emits electrons, which are then steered into a target (in a CRT TV, the...
  47. G

    I Time Dilation Exp: Answers to Questions on A & B's Experiences

    Hello everyone, The questions I am about to ask have probably been explained already, but even after everything I've read I still cannot understand how this experiment would play out and how to answer these questions. So without further ado here is the experiment: Imagine you have person A...
  48. kkris1

    I One way speed of light experiment proposal

    Just recently I came up with a new idea to measure one way speed of light and/or synchronize distant clocks: Let’s have two light sources at points A and B separated by distance d and sending constantly (perpendicular to AB) signals to clocks at A’ and B’ Let’s have an opaque rod of the length...
  49. Andy_K

    B Double Slit Experiment: Detection around slit?

    Dear All, I have a question on the double slit experiment. From the references I've read so far, they are focusing on the results of the detector AFTER the 2 slits. Let's say when photons are fired, how many % actually pass through the slits and get detected at the end? Would some (and how...
  50. davenn

    Cool ball and feather drop experiment

    some may not have seen this video done in a vacuum chamber enjoy
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