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. A

    Classical Home Experiment / Demo / Training Kit for students to use at home?

    Dear all, could you kindly recommend Physics Demo home kits (mechanics, Optics, Sound, Electricity/Magnetism) for secondary school level, to practice and learn at home? many thanks
  2. B

    B How is the measurement done for the double slit experiment?

    How is the measurement of which path the particle took done for the double slit experiment? When electrons are being sent through the slit. Or when photons are being sent through the slit. Is it an active process or a passive process? I haven't seen an explanation for this and perhaps this...
  3. R

    I Some questions about the photoelectric experiment

    Background: self-studying. Very confused. Here are some initial questions I have about the photoelectric experiment. Some more may pop up later. 1. The book says we know photons exist due to energy considerations (such as emission or absorption). They also say that this photon energy is...
  4. J

    I The Ensemble Interpretation and the Double Slit Experiment

    I am a big fan of Ballentine's book on QM and was reading the discussions about the Ensemble Interpretation. Although, I am not an expert on these matters I reject the idea of the wave function collapse as a fundamental postulate of QM. Instead, I've come to the conclusion that we don't...
  5. O

    Millikan Experiment Based Marble Mass Homework

    I arranged the masses in ascending order: 11.0 g 11.1 g 20.6 g 21.4 g 21.5 g 25.7 g 25.8 g 25.9 g 31.6 g 31.9 g I found the average mass of the marbles: 22.65 g I found the difference in masses of the marbles: 0.1 g 9.5 g 0.8 g 0.1 g 4.2 g 0.1 g 0.1 g 5.7 g 0.3 g I found the average of the...
  6. Someone_physics

    A Thought experiment in relativistic quantum mechanics?

    Background --- Consider the following thought experiment in the setting of relativistic quantum mechanics (not QFT). I have a particle in superposition of the position basis: H | \psi \rangle = E | \psi \rangle Now I suddenly turn on an interaction potential H_{int} localized at r_o =...
  7. ohwilleke

    B What's Delaying Fermilab's Muon g-2 Results Release?

    Fermilab's E989 experiment is conducting the first precision measurement of the anomalous magnetic moment of the muon (muon g-2) since the Brookhaven lab did so fifteen years ago. It is currently collecting Run-3 data for this experiment, and said that it would be releasing preliminary Run-1...
  8. Adams2020

    The sources of error in a diffraction grating experiment

    In a diffraction grating experiment, what can be the sources of error and also what effect do these sources have on the unknown quantity (wavelength) in the experiment?
  9. Silverbeam

    Can an object maintain uniform motion without any external force?

    Hi, I’m new here and I signed up to ask for some help with a physics problem. I’m not trained, nor am I receiving training, in physics. I’m a bachelor of Geoscience student halfway through my course. The problem I have is with understanding and testing the law of uniform motion (I think that’s...
  10. PainterGuy

    B Double slit experiment with electrons

    Hi, Could you please help me with the queries below? Thanks in advance! Question 1: I was watching this video. Between 8:36 to 9:44 the following is said: "But only firing particle by single particle at this barrier with the 2 openings and by recording dot by single dot where each of those...
  11. davidbenari

    A Which condensed matter experiment PhD group is the most fun?

    This is going to be controversial and might even be taken down, but I think what I will say is absolutely true, and I'm sorry if it offends people. I'm applying for the second time to condensed matter PhDs. I was in a group that did a lot of device fabrication as part of their experiments and...
  12. L

    What Are the Results of the Millikan Oil Drop Experiment?

    mass: 1.57x10^-19 kg voltages: 400, 457, 384, 369, 400, 355, 369, 436, 384, 369 distance: 0.1m gravity: 9.81 m/s^2
  13. AN630078

    Thought experiment: How would ocean levels change?

    I am not too sure how to approach this, initially I thought it may be more of a calculus and related rates of change problem, i.e. finding an expression how the volume and height of water change with respect fo time. I do not know whether this is the right idea or how to progress any further...
  14. starkreactor

    I Thought Exp: Gen Relativity & Time Dilation

    I am trying to understand a thought experiment I just posed, which is: if an observer is traveling near the speed of light, and sends out two photons; one in the direction of travel and one in the opposite direction, how does general relativity account for time dilation? The photon "in front"...
  15. H

    B Gravitational signature of a photon in a double slit experiment

    I'm trying to think of a how the double slit experiment can detect a photon without interacting with it in theory. In principal (not reality of course) does a photon have a gravitational signature which could be used to detect which slit it traveled through during the double slit experiment...
  16. R

    B A question about the double-slit experiment

    In the diagrams illustrating the double-slit experiment, I see waves extending longitudinally towards the the metal sheet. What if the waves were modeled differently so that they extended transversely in the diagrams? I've got the feeling that this can say something different.
  17. S

    I The velocity of Pilot-wave and the Double slit experiment

    Hello, Its been a while since I'm trying to understand the concept of the pilot wave theory and it's relation with the deBroglie wave. What is the fundamental difference between the two? My confusion comes from the double slit experiment. The velocity of the deBroglie wave is c^2/v so I...
  18. Axel Togawa

    I Double slit experiment and the Uncertainty Principle

    With the double slit, experiment we show the double nature of light and matter as wave and particle. In particular, the so called "which way" thought experiment illustrate the complementary principle. In my book, this experiment is analyzed putting a series of particles in front of one of the...
  19. WannaLearnPhysics

    Uncertainty of the Best Value from a Multiple-Trial Experiment

    For Example: Trial 1: 5.36 ± 0.03 Trial 2: 5.42 ± 0.04 Trial 3: 5.35 ± 0.01 Trial 4: 5.38 ± 0.03 Trial 5: 5.45 ± 0.02 What I did was take the average of the best estimates and the uncertainties. Best Value 5.39 ± 0.03 (0.03+0.04+0.01+0.03+0.02)/5=0.026=0.03
  20. patric44

    An experiment for the determination of hydrogen ionization energy

    hi guys i saw this experiment in an old book that uses the gas vacuum tube "thyratron" for determining the hydrogen ionization energy , the idea i guess is straight forward : we set the filament current to a specific value then the electrons starts to emit from the cathode traveling its way to...
  21. B

    I How many magnets are in the CMS experiment

    Hello! When I google about the CMS magnet I see that there is a 4 T magnet. However in the diagrams with muons, like this one, it seems to be another 2 T magnet beyond that. Where is that placed exactly. I assume it doesn't go around the whole detector, as that would affect the central region...
  22. A

    Experiment using an Ostwald Viscometer

    Summary:: Not sure how to My question is what is h2o , because ts is for example : 48,25 and what is ps . Is h20 the 0,99708? 48,25
  23. jaumzaum

    Pressure experiment with a burning straw protruding from a hole in a bottle

    Consider the following experiment: we have an open bottle, with a hole where we put a straw. We burn the outer side of the straw. We see smoke ascending outside and descending inside. Why is that? I would say the smoke has lower density than air outside, that's why it goes up. Inside the bottle...
  24. jaumzaum

    I Can a Match be Used as a Conductor in a Triboelectricity Experiment?

    Consider the following experiment. 2 coins are put in the position shown above, with a match above them. A boy scrubs a balloon on his hair and takes the balloon near the match. The match follow the balloon. The balloon will be electrified by friction, and it will induce opposite charges in...
  25. U

    B Help with IB Extended Essay Physics Experiment Ideas

    I'm having trouble coming up with a experiment to investigate for my IB Extended Essay as well as formulating my research question. Does anyone have any recommendations on similar (in terms of classical physics & abundance of background theory) physics experiments that can be done?
  26. K

    Is Air Resistance Negligible in Projectile Motion Experiments?

    Total acceleration equaled = -9.81
  27. J

    I Is Stern-Gerlach experiment a proper idealization of measurnment?

    I have met statements that Stern-Gerlach experiment can be seen as idealization of quantum measurement: we start with random direction of spin (continuous), end with parallel or anti-parallel alignment (discrete). Is it a proper analogy/idealization of measurement? How to characterize the...
  28. Jamister

    A An experiment that claims to doom Bohmian Mechanics

    I read in the article in Quanta magazine about an experiment with oil droplets that dooms Bohmian Mechanics, but I didn't understand why. Does anyone knows this experiment and why it dooms Bohmian Mechanics? The article is in the link...
  29. G

    Casimir Effect experiment and implications on motion theory

    Quantum mechanics has argued for years that space is not a vacuum. Arguments attempting to brush aside quantum mechanics vacuum theory claiming, it's 'just a quantum mathematical theory' can now put to rest. In this article, laboratory experimentation demonstrates that the Casimir Effect can...
  30. J

    B Thought Experiment: Exploring Violations of Bell Inequalities

    I have been thinking about the Violation of bell inequalities , trying to justify how non locality can be determined from violation of bell tests. I have been through Dr. Chinese page which has partially convinced me that there can be no hidden variables , but I need to understand what...
  31. Quarinteen

    EM fields and magnetic induction from an experiment

    If you take copper wire and wrap it tightly around a bolt will that alone create and hold a magnetic field? I add an image for clarification
  32. patric44

    Why the Stern-Gerlach experiment didn't detect the L?

    i recently read about the stern-gerlach experiment and found out that they did it in the first place to verify the principle of the "space quantization " introduced by Bohr , and they thought they did detect the quantization of the orbital angular momentum of ( L = 1 , m = 1,-1 ) neglecting the...
  33. A

    I The 1964 W. Bertozzi experiment

    I'll like to know if the 1964 Bertozzi experiment was repeated by others.
  34. C

    Trying to make sense of the double slit "experiment"

    How did you find PF?: A quick Google search of Physics forum gave me a link to this site. I have a good background in science (BSC Mathematics), but not specifically in Quantum theory. That happened after I left University. I have read lots, know a fair bit but wouldn't dare to claim I...
  35. H

    B What is the pattern in a double slit experiment near the slits?

    I am looking to this picture https://en.wikipedia.org/wiki/De_Broglie%E2%80%93Bohm_theory#Double-slit_experiment it seems that fringes only appear on a screen when it is not too close to the fringes. and that the electron near the screen would give a pattern as when the path is known. Is it right?
  36. AN630078

    What is the focal length of the lens?

    Question 1. i Suggest a reason why any uncertainty in the values of u can be neglected. I am really rather unsure how to answer this question but I have produced my opinion nonetheless. One could assume that the uncertainty in object distance u, i.e., the distance from the lens to the light...
  37. S

    Uncertainty in the measurement of the focal length in this experiment

    ##\frac{1}{f}=\frac{1}{u}+\frac{1}{v}## ##f = \frac{u.v}{u+v}## Let: u + v = w → w = 250 mm ± 8 mm Percentage uncertainy of v = (3/50) . 100% = 6% Percentage uncertainty of u = (5/200) . 100%=2.5% Percentage uncertainty of w = (8/250) . 100% = 3.2% Percentage uncertainty of f = 6 % + 2.5 %...
  38. I

    I Has this photon experiment ever been done?

    In the original experiment a photon 45 degrees polarized goes through two beamsplitters and comes out 45 degrees polarized and if you measure the individual path, you measure vertical or horizontal. I was just wondering, has the experiment below (or something simular) ever been done? Do we...
  39. F

    Does this QM experiment show that science is doomed?

    Here is the article: https://www.sciencemagazinedigital.org/sciencemagazine/21_august_2020/MobilePagedArticle.action?articleId=1611119#articleId1611119 If 2 experimenters (or people) cannot agree on a single observation does this mean that science which depends on many observers agreeing on...
  40. C

    I Two slit experiment with different sized slits

    If the two slit experiment is performed with one slit half the width -- or 1% or 0.1% the width -- of the other, how is the interference pattern affected.
  41. R

    B Does the Torricelli Vacuum Experiment Prove the Strength of Vacuum Forces?

    If Evangelista Torricelli truly created a vacuum, then there would be nothing in it, yet you can see through it which means light is obviously still in there (and who knows what else), right? If there was truly nothing in it, and glass is a highly viscous fluid, and fluids conform to fill empty...
  42. Hamiltonian

    B A thought experiment about the Sun vanishing

    suppose suddenly the sun disappears at a time t. at this arbitrary time t, the Earth should fling off tangentially to the point in its orbit at time t as there is no centripetal force keeping it in orbit. we know light takes about 8 minutes to reach the earth. so will humans on Earth experience...
  43. pasomatt

    Assistance with Sound Wave Reduction/Amplification Experiment

    I was conducting an experiment with a tone generator (330 Hz) in boxes of different sizes with a glass plate placed on top of the box. There is a receiver about .55 meters away. Without any interference, the receiver registered -41 db +/- 1 db. When the tone generator is placed in the box and...
  44. J

    I Is this a valid Wigner's friend experiment?

    1. Wigner's friend is inside a lab, and has a pair of entangled photons. 2. He measures one in the vertical axis. 3. He sends the other photon to Wigner. 4. Wigner can: a) measure it in the vertical axis (if so, he will get the same result as Wigner's friend). 5. Or Wigner can: b) send the...
  45. J

    B Speed of electrons in a 2-slit experiment

    In the 2-slit experiment using electrons, what speed do they travel at?
  46. L

    I Child's experiment to weigh air

    I've just purchased a book of child scientific experiments and it has an experiment that is titled 'Weigh some air'. It shows that if you make a scales with a piece of wood and a pivot and then balance two empty balloons on a either end and then fill one of the balloons with air the scales will...
  47. Jehannum

    B Stern-Gerlach experiment - please confirm this surprising result

    A SG device oriented along z-axis is used to prepare a stream of spin up particles from a randomised source. These are then passed through an x-axis SG device. If their spins were to be measured now they would be 50% left, 50% right. But instead, the two beams are recombined and passed through a...
  48. J

    I Repulsion before the screen in a double-slit experiment

    Consider a double slit experiment with electrons fired illustrated in the attached figure. One interpretation of this experiment is that each fired electron clones itself, one of the clone passes through one slit and the other through another slit then they reached the screen where they...
  49. sagigever

    Experiment involving surface tension for water and alcohol

    I really have no idea how to approach this question, I was thinking write ##F=mg## but I am not sure if I can write that even though
  50. P

    A Thought Exp: Transform Laws & Feedback Needed

    I'd like to get some feedback on the following argument. Gallilean mechanics, with the Gallilean transformation laws, is a perfectly consistent theory. Special relativity, with the Lorentz transformation laws, is another perfectly consistent theory. The question is - can we have some physical...
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