What is Experiment: Definition and 1000 Discussions

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. 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...
  2. 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.
  3. 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...
  4. 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...
  5. 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
  6. 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...
  7. 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...
  8. 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
  9. 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...
  10. 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...
  11. 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?
  12. K

    Is Air Resistance Negligible in Projectile Motion Experiments?

    Total acceleration equaled = -9.81
  13. 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...
  14. 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...
  15. 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...
  16. 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...
  17. 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
  18. 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...
  19. A

    I The 1964 W. Bertozzi experiment

    I'll like to know if the 1964 Bertozzi experiment was repeated by others.
  20. 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...
  21. 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?
  22. 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...
  23. 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 %...
  24. 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...
  25. 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...
  26. 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.
  27. 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...
  28. 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...
  29. 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...
  30. 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...
  31. J

    B Speed of electrons in a 2-slit experiment

    In the 2-slit experiment using electrons, what speed do they travel at?
  32. 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...
  33. 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...
  34. 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...
  35. 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
  36. 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...
  37. RemotePhysics

    How can I improve my Experiment plan?

    Just completed my experimental plan for the question above and would like some feeback on what I can improve, and how I can fix any errors in my plan? Also please do let me know what you would have done differently if you had answered this question...
  38. allisrelative

    Doesn't Wigner's Friend Experiment solve the measurement problem?

    If you look at the recent Wigner's Friend experiment, it seems to support Carlo Rovelli's Relational Interpretation which says there's no real measurement. Wiger's Friend carries out a polarization measurement. Before he does, the quantum system is in a superposition of horizontal/vertical...
  39. T

    Thermal penetration depth experiment

    I doing an experiment that involves thermal penetration of copper. Please advise me where to post if I choose the wrong spot. This experiment is being done with what I have on hand and my ability to work the materials. Materials 2.75 gal pot of water 6qt pressure cooker 100+lb of stripped...
  40. tanaygupta2000

    Young's double slit experiment

    Since slit-2 = 4 × (slit-1) Hence amplitude, a2 = 4a1 which gives i2 = 16×i1 So i(max) = i2 + i1 = 16i1 + i1 = 17i1 & i(min) = i2 - i1 = 16i1 - i1 = 15i1 => i(min) /i(max) = 15/17 but there's no such option. Kindly help me to figure out where am I doing error.
  41. wolfy

    B Has the Double Slit Experiment been Performed in a Near Vacuum?

    Where, When and Who has performed the Double Slit Experiment in a Near Vacuum Environment Cannot find it anywhere on Line Thank You
  42. S

    I Young's double slit experiment -- Question about this wavefront diagram

    Hello, I have a question about the blue waves coming from sources S1 and S2 in de next picture. The blue waves from sources S1 and S2, are those two resulting waves (interference of all wavelets, Huygens Principle) or are those blue waves two wavelets?
  43. mfb

    A Dark matter experiment XENON1T sees an excess at low energies

    Press release arXiv ~3.5 sigma significance and it could be caused by tritium contamination - although it's unclear where the tritium would come from. If it is really new physics then solar axions or a magnetic moment of neutrinos would fit well. The key plot, figure 5 in the arXiv version...
  44. faca

    B Curvature radius question for my muon beam experiment

    Hello, I've a particle beam moving along the z-axis. The beam goes through a dipole magnet. I studied the hit position in a tracker after the magnet and I noticed that there are hits at 2 different x coordinate (the x asix is transverse to the z one). Let's call Delta x the shift between the 2...
  45. dRic2

    I Phonon Number Conservation in a Single Mode Oscillation Experiment

    Suppose I prepare an experiment where I excite a single mode of oscillation of the lattice, that is something like ##u(x, t) = Ae^{i(kx-\omega t)} ## (in the classical limit). The energy corresponding to that mode should be ##E = \frac 1 2 \rho L^3 A^2 \omega^2 ##. If I equate this equation to...
  46. J

    I Double Slit Experiment Question

    I'm wondering if this would be a way to interpret the double slit experiment. In other words, when we observe an electron in the present, it goes through one slit or the other as a particle. However, if we do not observe it, it goes through both at once as a wave; we only see evidence of it...
  47. B

    Finding the distance between slits in double slit experiment

    Hi so I have been struggling on a part of a question that I'm not too sure on how to solve For some reason PF is not allowing me to pose an image of the question on here so I have provided a link to it Question link: And here is what I tried to do so far, I drew a sketch of a diagram to help...
  48. A. Neumaier

    A Advanced models for the Stern-Gerlach experiment

    A detailed discussion of measurement in the Stern-Gerlach experiment can be given in the POVM setting; see this post.
  49. E

    B Query about Pound-Rebka like experiment

    I was helping (or at least attempting to help...) my sister with this question but ended up getting confused about one part myself! The idea is that you have a mass ##m## at a height ##h## which you drop, and on contact with the ground it is converted into a photon of equivalent energy...
  50. K

    Eddy currents in Faraday's Law Experiment

    My explanation: A circular coil is connected to an AC supply at a frequency of 30-50 kHz (radio frequency). Therefore, an alternate current will be running through this “primary” coil, producing an alternating magnetic field. This magnetic field periodically decreases in strength, alternating...
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