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. D

    B How Does the Double Slit Experiment Show Both Particle and Wave Behaviors?

    From my shallow understanding, when we shoot a small amount of electrons through the slits while observing, the observation interfere with the electrons and the quantum system and thus collapse the wave function, making the electrons behave like a particle and form a 2-slit pattern on the...
  2. K

    Why Did Water Droplets Fail to Suspend in Millikan's Early Experiment?

    Homework Statement When Millikan first performed this experiment, he used water droplets instead of oil. He found he could not suspend the droplets; they would start to move up. Why did this happen? Homework Equations N/A The Attempt at a Solution The water droplets would have been so small...
  3. C

    How can I recreate this pressure boiling experiment

    Hi all, I was just wondering how I could recreate this at home What parts do I need? Thanks, Harry
  4. ShayanJ

    Stern-Gerlach experiment as a measurement

    Its been a while that I'm thinking in what sense we can say the SG experiment is a measurement. What I concluded, is that there are two kinds of measurements. 1) Measurements that advocates of the ensemble interpretation (like our own @vanhees71) declare as the only one that QM has anything to...
  5. C

    B Quantum Mechanics vs. Pilot-Wave thought experiment

    Hello. I want to share a thought experiment that could tell Quantum Mechanics apart from Pilot-Wave interpretation. It goes like this: Quantum Mechanics vs. Pilot-Wave: Quantum Mechanics: Waves collapse to particles. Waves disappear when particles are detected. Pilot-Wave: Waves are real but...
  6. L

    B Delayed choice quantum eraser experiment interference pattern question

    If I understand the delayed choice quantum eraser experiment correctly, it's essentially set up in the manner as the double slit. The only difference is that the detectors are set up in front of the double slits. It was thought that if there was an interference pattern that appeared then that...
  7. Sophia

    What does Double slit experiment actually mean

    I'd like to ask what exactly do the results of double slit experiment mean? I must confess that I've read about this mainly in New Age literature where it was used as a "proof" that our consciousness changes reality. I know that Physicists probably don't like such explanations :eek: So I'd like...
  8. G

    Many questions about the LIGO Gravity Wave Experiment....

    I'd like to understand the details behind the LIGO experiment a bit better: How do scientists know that the gravitational waves detected by LIGO originated from two specific black holes (located a billion light years away)?Does the LIGO result confirm the existence of black holes?Was it only...
  9. hdp12

    PV battery potential.... coming up with experiment

    Hello there everybody In my research group we've been working on PV cells and exploring non-conventional techniques to try and raise the efficiency of some of the lesser explored materials that have PV potential. Well, last week while testing one of our cells in a solar simulator, we noticed...
  10. Priyadarshini

    Young's Double Slit Experiment

    When the slits are made narrower (but with same separation) why are more fringes produced? If the slits are narrower, less light enters, so less light interferes with each other, so lesser number of fringes should be produced, isn't it?
  11. J

    Quantum antenna thought experiment

    If you have a classical antenna absorbing an electromagnetic wave, the charged particles inside the antenna will be given momentum in the directions perpendicular to the direction of propagation of the EM wave (because the E and B fields are perpendicular to propagation). If just a single...
  12. V

    Steam's Effect on Wood: A Gedanken Experiment

    I have a piece of wood, I decide to insert it into a steamer to observe what happens, because I'm not sure. There could be multiple possibilities. Wood has conductive tissue, steam may get trapped within pressing it outwards. The temperature dependent expansion definitely happens. But steam not...
  13. sciencejournalist00

    I Does the double-slit experiment create path-entangled states

    If I try to send a vertically polarized photon through one slit and a horizontally polarized photon through the other slit, they actually go through both slits. But when I measure and find out through which slit the horizontally polarized photon went, I automatically know that the vertically...
  14. E

    Physics Experiment Ideas Using Snowboarding

    I need an idea of what to test if I were to do a physics experiment about snowboarding. It can be one involving someone riding a snowboard or an empty snowboard. However, I would like it to be relatively simple, as in my rider doesn't have the skills to ride a half pipe or do any big jumps. I...
  15. Matt Benesi

    B Name of experiment confirming mass-gravitational attraction?

    Not sure where this particular question belongs. Do you know of any Cavendish type measurements of G, in which the mass (and ~density) of the attractors (gravitational sources) are controls, and the number of particles (fermions or maybe quarks+leptons) is the independent variable? The...
  16. H

    Correct interpretation of double slit experiment?

    Hiya, Another me trying to grasp some physical experiment. I'm working myself through a Dutch popular science book "Snaartheorie" (String Theory) by 'our' professor Marcel Vonk: it's meant to give the reader a maths-less impression of the theories behind string theory. Vonk starts with an...
  17. 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...
  18. ft92

    Why is it difficult to determine the center of a Newton's ring pattern?

    can anyone please explain to me why it's not possible to determine accurately the position of a centre of a Newton's ring pattern? I know that in a Newton's ring only the distance between one side of the ring to the other i.e. the diameter can be accurately determined, not the distance from the...
  19. mrsmitten

    I Why is the medium in the Michelson Morley experiment ignored

    Normally in explaining the aether model of light it is said that all waves need a medium, so just like sound uses air, light uses the aether. To my understanding sound can travel through gas, liquid and solids just fine without air being partially entrained in the materials. Sound does not use...
  20. T

    Confused about EPR Thought Experiment

    In "Einstein's Moon" by F. David Peat there is a description of the EPR thought experiment,but I am confused by Bohr's response to Einstein given in Peat's book. In the EPR as described by Peat, particle A and particle B move in opposite directions after the entangled particle (AB)...
  21. A. Neumaier

    An abstract long-distance correlation experiment

    Inspired by stevendaryl's description of an EPR-like setting that doesn't refer to a particle concept, I want to discuss in this thread a generalized form of his setting that features a class of long-distance correlation experiments but abstracts from all distracting elements of reality and from...
  22. M

    Amplitude and Young double slit experiment

    Homework Statement For a question in a worksheet (the actual question is irrelevant), my physics teacher said, in the context of the Young double slit experiment with light, if you make one of the slits smaller, then the amplitude of light from that source will also decrease. Is that true...
  23. Henry T

    Safety of a Small Scale Electrolysis Experiment

    I'm going to perform a small scale electrolysis experimenter of water. I want to find out how the rates of the gases are produced when the amount of electrolyte added to the water is changed. I'm going to use baking soda (NaHCO3) as the electrolyte but I just wanted to make sure that I won't be...
  24. AwesomeTrains

    Effective mass dependency on the donator atom?

    Hello pf Is the effective mass dependend on the donator atom in a semiconductor? In our experiment we have calculated the effective mass in a germanium semiconductor, doped with an unknown atom. It is 0.39m_e. From the internet we know that the effective mass is 0.33m_e. Is our result...
  25. B

    Snell's law experiment with glass block

    Homework Statement [/B] A student wants to find the refractive index of a rectangular block of glass. He draws around the block and marks the position of a ray of light that travels through the block. With the block removed, the student can draw in a normal line and then measure the angle of...
  26. Dan Allred

    Thought Experiment: How would life on Earth have developed if....

    What would have happened to to the evolutionary process had the Earth's axis of rotation had no tilt? What comes to me first would be a total lack of anything based on the year calendar. There would be no deciduous trees or dormant grasses, certain animal species would have no particular mating...
  27. A

    Why no smear in Stern-Gerlach experiment?

    Why do the silver atoms not exist in a superposition of states with every possible mixture of spin-up and spin-down? Thermal photons do.
  28. M

    Double Slit Experiment: Largest Size for Wave-Particle Duality

    I know when they performed the famous double slits experiment they used either electrons, or photons. I am trying to find out what is the largest size we could use (proton, molecule, etc) where the probability of wave-particle duality to occur in the experiment drops to something negligible...
  29. S

    Energy loss when boiling in an water experiment -- help please

    Homework Statement Hi, as a part of my lab report I have to conduct this experiment : Fill a pot with tap water and boil it, determine then how much of the energy that the kitchen surface produced, actually went to the water itself. Consider the water having an initial temperature of 10 °C. In...
  30. I

    GR Multibody Problem: Comparing Experimental Measurements

    I have a generic question on solution procedure. Suppose I consider a system of several point-like bodies interacting only via gravitation. I formulate PDE+ODE system, containing EFE and geodesic motion of the bodies. Since EFE do not define metric uniquely, I need to impose a particular...
  31. C

    Trying to come up with possible topic for physics experiment

    Homework Statement This doesn't follow the homework format very well, but I'm sure if I posted it elsewhere it'd be moved here. I'm looking for possible topics for a physics exploration (with experimentation) that has to be appropriate for a higher level physics student in high school. I'd...
  32. N

    Length contraction experiment results

    I was looking at the barn door paradox, http://math.ucr.edu/home/baez/physics/Relativity/SR/barn_pole.html But supposing that instead of a barn, there was a piece of measuring apparatus which was in two halves, with a gap in between through which the pole would pass. One half of the measuring...
  33. Vinay080

    Justification for the acceptance of Coulomb's law

    I read the Coulomb's first memoir on Electricity and Magnetism (Louis L. Bucciarelli english translated version), and found it to contain only three trials (as complained by many) to reach the conclusion of a 1/r2 equation for the force. And many seems to have also complained for not having able...
  34. 24forChromium

    Engaging experiment involving chromate and acidity?

    I am trying to get an idea of an experiment that deal with the equilibrium of Chromate and Dichromate with acidity being the independent, but I am not sure in what situation would a equilibrium between these two chemicals occur. Beside the interchange of these two anions with each other, I was...
  35. M

    Steam generation for an experiment

    What would be the best, cheapest way to generate steam intended for introduction to a device for testing? I would use a standard American 110v three-prong outlet as a power source for the steam generator. All I really need is a steam source with an absolute pressure of 2 atm/202650 Pa/29.39...
  36. weezy

    How is the uncertainty relation preserved in this experiment

    For an electron can I not do the following to determine both the position and momentum? I take a screen with a small hole and I eventually make the hole smaller and smaller. Cathode rays emitted will hence get diffracted after passing through the hole making momentum more and more uncertain...
  37. M

    B FTL Paradox: Grandfather Paradox Explained

    So here it goes: 2 points in space A & B. 1 superluminal object (fixed at 10c, no acceleration) that periodically transmits photons as soon as it starts moving. 1 observer with a very high accuracy photon counter removed a sufficiently large distance from the 2 points for light to take a small...
  38. D

    Finding a Class I Laser Pointer for a Science Fair Experiment

    I am doing some experimentation, for a science fair. And I want to make sure I the laser pointer I use is Class I (conceivably, I may change that, but any class of laser can be used to replicate results similar to the double slit experiment correct?). Can anyone direct me as to where I may be...
  39. Clara Chung

    Double slit experiment with a slit covered.

    Homework Statement A thin flake of mica (n=1.58) is used to cover one slit of a double-slit arrangement.The central point on the screen is occupied by the 7th brigth fringe.If lamda = 550nm, what is the thickness of the mica? Homework Equations path difference d=(n-1)*thickness d=7*lamda...
  40. conquest

    Experiment showing energy levels of light are quantized

    Although I have not been thinking very much about actual physics for while now I suddenly got the urge to read a little bit about it and I decided to start by checking out the birth of quantum mechanics again. In the book quantum theory by Bohm in chapter 1 the ultra-violet catastrophe and its...
  41. V

    Time Constant ≠ Time constant from experiment

    Homework Statement Hello, In a lab experiment, we wanted to compare the time constant in a simple RC circuit by comparing the value of Resistance * Capacitance that we measure directly and the value of RC that we get from the procedure. The procedure entailed using a wave generator and an...
  42. shio

    Why do we need to square the separation in Coulomb's experiment?

    Coulomb experiment torsion balance. I know that electrical force is inversely to the square of the separation r ...My question is why we take r square? why we need square? And another question, why Q1Q2(multiplication of charges) is proportional to electrical force? (why we need to multiply...
  43. R

    Uncovering the Illusion: A Closer Look at the ESP Experiment with Volunteers

    Here is a trick performed very elegantly. This trick is a bit natural looking also, as the volunteer's guess is correct but not a perfect one. What phenomena is really going on here?
  44. I

    OPERA experiment - Special Relativity

    Homework Statement In 2011, researchers at the OPERA experiment thought they had seen neutrinos with mass m and energy E = 28 GeV moving faster than light. The baseline between the source and the detector was 731 km, and the neutrinos seemed to arrive 60.7 ns early, compared to the maximum...
  45. P

    Possible explanation for a Bell experiment?

    The following assessment of a Bell experiment is based on N. David Mermin's example and is intended for persons with very little understanding of mathematics and physics (myself included). Assumptions (A1) A source emits a pair of particles with some opposite pieces of information. (A2) The...
  46. S

    B Speed of Light & Thought Exp: How to Send Info 186K Miles Instantly

    I've built a rod 186K miles long, of ultra-light, ultra-rigid material. I am on one end of the rod, and an observer is at the other end (we're both in the near vacuum of space). I want to send a signal to the observer on the other end of the rod signaling whether the Packers have won the...
  47. S

    Tachyons, the Double Slit Experiment, and a bit of Fiction

    Hello, All! I'm writing a bit of fiction, and as a newcomer to the world of Quantum Physics, I thought I'd clarify a few concepts here, to avoid lapsing into technobabble. I'm trying to make something along the lines of the film Primer, which tries to incorporate as much realism as possible...
  48. H

    Thermodynamics or thermal physics

    What are some interesting experiments for doing research in thermal physics or thermodynamics?
  49. N

    I Double Slit Experiment: Questions Raised & Explanations Needed

    I was watching a video about the double slit experiment because I found it interesting, However, watching this vid raised more questions than it did answer. I would like to know why did the outcomes of the experiment only change when we observed it... wasn't the electron interacting with...
  50. T

    Why are the peaks in the Franck-Hertz experiment broad?

    As opposed to discrete values, given that the energy levels are discrete. The gas in mind here is helium. When studying the peaks a plot of accelerating voltage vs current that match up to the energy levels they should be discrete, right?
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