Experimental Definition and 527 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. U

    Photon spin - experimental evidence

    I read somewhere that if a beam of photons all of like polarization are directed towards the surface of a disk (the disk being capable of rotation), the disk will rotate. This rotation is supposed to be experimental evidence confirming that photons have angular momentum. Is this true?
  2. W

    LaTeX Is latex uncommon among experimental physicists?

    To put my question in perspective, I'm starting grad school in the fall, and as an undergrad I was pretty sure I wanted to be a theorist so my range of experience with experiment is limited - I like reading papers off arxiv, and it's pretty rare to pull a theory paper that isn't typeset in...
  3. G

    Deriving Uncertainties for m and b in Least Squares Method"

    Hi there: First of all, I thank all the people who have answer my questions until now, they were really helpful for me... Now I have another Doubt, in the least squares method, in order to fit experimental data to find an straight line y = m*x + b. We need to obtain the...
  4. J

    Many Worlds experimental evidence

    I keep hearing that the "many worlds interpretation" is experimentally different than the collapse theories. But I haven't heard of anything other than "quantum suicide". Is there anything else? As far as quantum suicide, I fail to see how this differs from collapse theories. Isn't each...
  5. W

    Experimental Data: Light Velocity Change

    Are there any experiments that show how light is treated as a frames velocity is changed (not the light source, rather the "eye".) For example if a huge clock that is counting down from 10 is 10 light seconds away before I accelerate (at t=0) to a velocity where my length contraction is *.5 (I...
  6. D

    Experimental work to prove that the Drag Coefficient of a sphere is 0.5

    Is there any experiments I could do to prove that the Drag Coefficient of a Sphere is more or less 0.5 depending on the roughness of the sphere?
  7. S

    Stern-Gerlach Experimental Calculation

    I've run into a problem which has been bugging me for days. I know its related to the Stern-Gerlach experiment about firing hydrogen through an inhomogeneous magnetic field, but all i can do is give a vague qualitative description of the answers, and not an actual numerical one (because I don't...
  8. F

    Chemistry Experimental Molecular Weight higher than Literature Value

    Homework Statement I just purified alkaline phosphatase, and my calculated molecular weight is 100000 g/mol, while literature value is 89000 g/mol. According to how others in my lab did calculations, my calculations are performed correctly, so I am left to explain why my purification is...
  9. pellman

    Experimental verification of QFT?

    What are the important experimental verifications of QFT that someone studying QFT should be familiar with? The wikipedia QED article mentions the anomalous magnetic moment of the electron and the Lamb shift. The Higgs Mechanism article states "Although the evidence for the Higgs mechanism...
  10. F

    Use the experimental values to calculate the enthelpy change in the system.

    Use the experimental values to calculate the enthalpy change in the system. Observation Experiment Quantity of reactant 1 100.0 mL of 1.00 M KOH(aq) Quantity of reactant 2 100.0 mL of 1.00 M HBr(aq) Initial Temperature (oC) 20.0 Final Temperature (oC) 22.5
  11. Y

    Experimental proof of electrostatic equilibrium

    Hey, In my physics we derived certain properties of conductors in electrostatic equilibrium using Gauss' law. One property seemed to "mathematical" to me. It says that the whole charge of a conductor in electrostatic equilibrium is located at the surface. The proof is at follows. Since the...
  12. G

    Should linear regression always be forced through the origin?

    Wasn't sure which section this should be in, so please move if inappropriate. If a plot between two variables theoretically should pass through the origin, should you force the linear regression through the origin. I seem to get a much better value for my gradient when forced through the origin...
  13. E

    More experimental modal analysis

    Hi, I'm trying to use experimental modal analysis to determine the modal parameters of a beaker. I'm using a shaker and have successfully obtained FRF's (I think!) Has anybody got any idea what I've to do from here? I've read what feels like a million articles but can't figure out how to...
  14. T

    Is an Impact Hammer Setup Suitable for Lightweight Modal Analysis?

    Hello, I need some help with setup/equipment used for a study to determine the natural frequencies on some small, lightweight samples (12in x 1.5in x .12 in.) in a catilever beam setup. The samples are made of carbon fiber and kevlar so they are fairly flexible to begin with. I am working on...
  15. DaTario

    Experimental distinction between states with one and two photons

    Hi All, Does anybody know if there is an experimental setup which is able to distinguish between a state of light with one photon and state with n = 2 ? This is about the bosonic behavior of light, according to which two photons may be in the same physical state - and in stimulated...
  16. T

    Selectivity of computational physics vs. theoretical vs. experimental?

    Pretty much every professor in my physics department has said that it when it comes to American physics graduate school, it is harder to get in as a theory student than as an experimentalist. Do graduate programs consider computational physics, numerical material sciences, etc... essentially...
  17. J

    Does Alan Hatcher's Topology book Work on 'Experimental' PDF Readers?

    Does anyone here have one of these book readers? I want to know how good the 'experimental' PDF support is. For instance, will it display Alan Hatcher's Topology book?
  18. wolram

    An apology and thoughts on the cost of experimental cosmology

    My posts have been rude i am just annoyed that all though i have learned a lot about cosmology i have learned nothing that matters, you guys spend years of hard work doing things only you can, i wish you had a bigger budget to work with, so that theory could be tested, i know you would like...
  19. jtbell

    FAQ: Experimental Basis of Special Relativity

    The section of the Usenet Physics FAQ titled "Experimental Basis of Special Relativity" has been cited here many times. I've just discovered that Tom Roberts has recently revised it. It now has information on experiments performed since the last edition seven years ago, and a larger section on...
  20. M

    Programs Experimental data in theoretical PhD?

    Hi all, I was wondering if PhD students in theoretical aspects of cosmology,gravitation, black holes... etc do any/much analysis of experimental data, and just mainly omit observational technique, or if their entire education is in learning physical theory and making predictions and solving...
  21. A

    Whats an experimental Physicist?

    First off thank you all for all the advice that has been given. I am new to this forum but I've already received plenty of good advice. So, I love physics. I have decided that that is what i want to earn degrees in (phd if I am cut out for it). My math knowledge is ok. grades in the high...
  22. K

    Theoretical or Experimental Undergrad

    Hello everyone, I have a couple of hopefully easy questions about undergraduate degrees. I am a 3.74 GPA student at my university and am currently in my 3rd year of college, on a 5 year plan. I am a double major in both Physics and Applied Mathematics. The following are my questions. 1)...
  23. A

    Extended Experimental Investigation.

    My teacher has given me a Extended Experimental Investigation to do that requires physics. I know a bit about it (the very basics) and I'm not sure on a few things about it. For my task I have forgotten to measure my displacement and I was wondering if anybody knew a way I could still find it...
  24. S

    News from P.I. workshop on experimental search for QG

    News from Claus Lammerzahl, from Bremen, on success yesterday 6 Nov. 07 of production of BEC in microgravity in a drop tower experiment: Yesterday the first BEC in free fall was produced by a team at Bremen University. A condensate of 10^4 to 10^5 atoms was created in a few milleseconds in a...
  25. S

    How Much difference b2in theoritical and experimental astrophysics?

    Can you tell me How Much is the difference between theoritical and experimental astrophysics?
  26. marcus

    Experimental Search for Quantum Gravity (schedule of talks)

    Bee Hossenfelder (who used to post here as "Hossi") has organized a 5-day workshop on XQG. A brief summary with links: http://www.perimeterinstitute.ca/esqg07/ The schedule of talks (5 Nov - 9 Nov) is here...
  27. D

    Calcium Role in Depolarization: Evidence & Experiments

    any ideas of which experiments best illustrate this Homework Statement Homework Equations
  28. B

    Finding gravity through experimental data

    Homework Statement Experimentally measured time of fall vs. distance for a freely falling object Distance, x (m) Time, t (s) 0.1 0.148 0.2 0.196 0.3 0.244 0.4 0.290 0.5...
  29. A

    Experimental proofs of increase of mass with v

    Is there any experiment that shows the increase in mass ( or kinetic energy ) of a moving body when seen from an observer at rest ? I know that sincrotons ( particles accelerators ) must change the frequency bla bla .. But once that these particles have been accelerated and hit a target...
  30. M

    Experimental calculation of Birefriengence

    I was wondering if any of you guys could help me. Is there any simple way to set up an experiment to calculate the birefringence of a birefringent crystal? I've trudged through papers and the most helpful one was "Measuring birefringence properties using a wave plate and an analyzer" by...
  31. P

    Experiment: Checking Biot-Savart's Law

    how does one experimentally check biot-savart's law
  32. Mk

    About experimental particle physics

    I intend for this to be in General Discussion, which is why I put it here, please don't move it, but move it if you reeally have to. :frown: http://www-d0.fnal.gov/Run2Physics/WWW/results/prelim/HIGGS/H23/H23.pdf I don't know much about particle accelerator data, but page 6 looks pretty...
  33. H

    Fourier analysis of my experimental data

    hi Im doing a project about chaos theory. Over the past few weeks I've built a Lorenzian waterwheel (its a waterwheel with buckets with holes in them, it shows chaotic behaviour.) One of the aims of the experiment was to try and plot the Lorenz attractor. The lorenz attractor is a strange...
  34. J

    Is General Relativity Fully Verified by Experimentation?

    A simple question of a curious person: How well is the general relativity verified experimentaly? In particular, are most of the tests conserned merely with the linear approximation of the gravitation? Or is there more or less direct evidence for the validity of strong gravitation fields, or...
  35. O

    Engineer -> Experimental Physicist -> Theoretical Physicist

    New member ! This is my first post. Long ago, I remember one of my friends talking about how engineers dream of becoming experimental physicists who in turn dream of becoming theoretical physicists. I remember the context but don't remember whether it was an explicit joke or musings of some...
  36. L

    Speed of light in the universe, experimental data

    I would like to compile direct and indirect data on the speed of light in the universe.o:) How much evidence do we have that it is constant, even close to a black hole? What kind of observations could be relevant to answer such a question? Thanks for your comments, links and references...
  37. N

    Bohr Magneton experimental value

    Dear PF, Could you please advise me where I can find the up to date experimental value of Bohr magneton with its uncertainty? Thanks a lot
  38. S

    Car Aerodynamics: Experimental trials not agreeing with lift theory, help

    Hi, I'm currently doing a research study on the effect of the presence of a rear car spoiler on the lift of a vehicle at low speeds As far as my understanding, with an increase in air velocity, there should be an increase in lift on the car. My trials however show that with an increase in air...
  39. L

    Bremsstrahlung near the cutoff frequency, experimental data

    Goodmorning, I would be interrested in experimental data regarding the Bremsstrahlung process near the quantum mechanical cutoff, possibly single events data. I thought that maybe something like a bubble chamber picture could illustrate this process. This is maybe a naïve dream but this...
  40. C

    Experimental and Theoretical Physics

    What are the perks and cons to being an experimental or theoretical physicist? and Is it possible to work on both areas? Thanks in advance Charonic
  41. P

    Experimental Proof of Electrical Charge

    Hi, I have a question about the transfer of electrical charge from object to another. Basically, my professor stated that if you rub a rod with certain matierials, the rod will become charged. This is due to the convention that Ben Franklin came up with called the triboelectric series. So...
  42. L

    Important discoveries in HEP, experimental

    I was wonder what you felt the important experimental discoveries in high energy physics over the past twenty five years have been? This is a subject I'm not familiar with and would like to do a bit of reading on my own. For instance, I imagine the possible mass of the neutrino would be on...
  43. U

    Experimental evidence that confirms or points toward extraspatial dims

    Is there any experimental evidence that confirms or points toward extra spatial dimensions? I have been looking around for a bit, couldn't find anything.
  44. mbrmbrg

    Accuracy of experimental values

    We did an experiment with abysmal accuracy. I'm now writing up my report and would like to meaningfully express the error between calculated and measured values. EXAMPLE calculated T=0.284 measured T = 0.201 I want to express the difference between them as follows: % difference...
  45. B

    Experimental evidence has ruled out (falsified) string theory - LQG still viable

    here's the link http://www.newscientist.com/channel/fundamentals/mg19125675.100-atomic-jitters-hint-at-quantum-spume.htmlin a nut shell 1- pollen in water jiggles - other small particles also jitter in solution. 2- einstein explained this as brownian motion & atoms 3- Einstein did not directly...
  46. Y

    Experimental evidence of higher dimensions. What will they be?

    Has there been any direct or indirect evidence from particle accelerators, telescopes, or observatories that the universe has more than 3 spatial dimensions? If not, what kind of evidence or data are particle physicists looking for? Are there some unexplained phenomenon that could only be...
  47. P

    Experimental Proofs of Special Relativity: Myons, Bertozzi & More

    Hi Im new in this Forum. I am from Switzerland, in the first year of Physics at University. Please forgive some mistakes I might will make in english I read a little bit in advance for the next years about the SRT and its relation to other fields of study. Basically I wanted to know...
  48. ZapperZ

    Experimental interference of independent photons

    Don't miss this paper from the Zeilinger group: R. Kaltenbaek et al, PRL 96, 240502 (2006). In particular, read the first paragraph: Zz.
  49. S

    Experimental Evidence and QFT.

    After reading one of ZapperZ's posts in the Relativity subforum, I just thought I'd ask the following: What predictions of QED, QCD, Electroweak and the Standard Model still aren't confirmed? I'd be particularly interested in hearing unconfirmed predictions from QED.
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