The Naked Scientists
  • Login
  • Register
  • Podcasts
      • The Naked Scientists
      • eLife
      • Naked Genetics
      • Naked Astronomy
      • In short
      • Naked Neuroscience
      • Ask! The Naked Scientists
      • Question of the Week
      • Archive
      • Video
      • SUBSCRIBE to our Podcasts
  • Articles
      • Science News
      • Features
      • Interviews
      • Answers to Science Questions
  • Get Naked
      • Donate
      • Do an Experiment
      • Science Forum
      • Ask a Question
  • About
      • Meet the team
      • Our Sponsors
      • Site Map
      • Contact us

User menu

  • Login
  • Register
  • Home
  • Help
  • Search
  • Tags
  • Member Map
  • Recent Topics
  • Login
  • Register
  1. Naked Science Forum
  2. Non Life Sciences
  3. Physics, Astronomy & Cosmology
  4. How are the results of the double slit experiment recorded?
« previous next »
  • Print
Pages: [1]   Go Down

How are the results of the double slit experiment recorded?

  • 8 Replies
  • 2996 Views
  • 3 Tags

0 Members and 1 Guest are viewing this topic.

Offline Harri (OP)

  • Sr. Member
  • ****
  • 106
  • Activity:
    0%
  • Thanked: 6 times
    • View Profile
How are the results of the double slit experiment recorded?
« on: 02/07/2017 20:14:22 »
I have been reading about the double slit experiment and the surprising results that are witnessed. What I am not sure about is, when the experiment is observed or recorded the results return to what you would expect, just 2 bars of light. How then are the surprising results observed or recorded then?
« Last Edit: 02/07/2017 20:43:10 by chris »
Logged
 



Online evan_au

  • Global Moderator
  • Naked Science Forum GOD!
  • ********
  • 9013
  • Activity:
    75.5%
  • Thanked: 884 times
    • View Profile
Re: How are the results of the double slit experiment recorded?
« Reply #1 on: 03/07/2017 02:29:12 »
You can record the results of the double-slit experiment:
- With your eyes
- on chemical photographic film,
- direct onto a camera CCD (eg a SLR with the lens removed)
- By shining onto a screen, and recording the image from the front or rear

To get a good result, you need:
- A coherent, monochromatic light source, eg a bright laser pointer
- Two slits that are very narrow, and very close together - both distances close to the wavelength of the light being used
- A sensor able to resolve image details that are very fine - similar to the wavelength of the light source.

If the slots are too wide and too far apart, the result will be two bars, ie the interference fringes are too faint and too numerous to be detectable.

See: https://en.wikipedia.org/wiki/Double-slit_experiment

Warning: Do not look straight into a bright laser pointer. Always shine it on a screen and look at the screen.
Logged
 
The following users thanked this post: Harri

Offline hamdani yusuf

  • Naked Science Forum King!
  • ******
  • 1750
  • Activity:
    100%
  • Thanked: 51 times
    • View Profile
Re: How are the results of the double slit experiment recorded?
« Reply #2 on: 03/07/2017 12:34:05 »
In my topic https://www.thenakedscientists.com/forum/index.php?topic=66301.0
I show double slit experiment, which is just a special case of diffraction with four edges obstruction.
Logged
Unexpected results come from false assumptions.
 
The following users thanked this post: Harri

Offline hamdani yusuf

  • Naked Science Forum King!
  • ******
  • 1750
  • Activity:
    100%
  • Thanked: 51 times
    • View Profile
Re: How are the results of the double slit experiment recorded?
« Reply #3 on: 03/07/2017 12:40:46 »
If we assume that light is stream of particles, just like Newton did, the occurence of light and dark bands on the screen is an unexpected result.
If we assume that light is a wave, akin to wave of water surface, then the unexpected result will show when the intensity is extremely low,  undetected by naked eye, hence requires very sensitive sensor, such as photomultiplier.
Logged
Unexpected results come from false assumptions.
 
The following users thanked this post: Harri

Offline Harri (OP)

  • Sr. Member
  • ****
  • 106
  • Activity:
    0%
  • Thanked: 6 times
    • View Profile
Re: How are the results of the double slit experiment recorded?
« Reply #4 on: 03/07/2017 21:55:01 »
I guess what I really tried to ask wasn't made clear, and perhaps even now it still doesn't make sense?

I watched this short animation 

When scientists try to 'observe' the interference pattern, it resorts back to the original non interference pattern. It's as if it knows it is being observed/watched.

But I was wondering, how do scientists know about the non interference pattern? Surely it is through observation/being watched?

If you watch the video and understand my question, then great. If my question doesn't make sense then ... thanks for reading and for the answers above already given.
Logged
 



Offline chris

  • Naked Science Forum King!
  • ******
  • 7942
  • Activity:
    6.5%
  • Thanked: 273 times
  • The Naked Scientist
    • View Profile
    • The Naked Scientists
Re: How are the results of the double slit experiment recorded?
« Reply #5 on: 04/07/2017 00:12:48 »
Hi @Harri

I understand what you are saying, which is, I believe, "if making the observation forces the photon to 'choose' a slit and causes the interference pattern to collapse, how do we ever see the interference pattern?"

The answer is that when you observe the pattern you are not observing individual photons but the sum action of many; it's not until you rig the experiment that you are essentially registering single photons that the behaviour breaks down when you try to watch them.
Logged
I never forget a face, but in your case I'll make an exception - Groucho Marx - https://www.thenakedscientists.com/
 
The following users thanked this post: Harri

Offline hamdani yusuf

  • Naked Science Forum King!
  • ******
  • 1750
  • Activity:
    100%
  • Thanked: 51 times
    • View Profile
Re: How are the results of the double slit experiment recorded?
« Reply #6 on: 04/07/2017 07:15:29 »
Quote from: Harri on 03/07/2017 21:55:01
I guess what I really tried to ask wasn't made clear, and perhaps even now it still doesn't make sense?

I watched this short animation 

When scientists try to 'observe' the interference pattern, it resorts back to the original non interference pattern. It's as if it knows it is being observed/watched.

But I was wondering, how do scientists know about the non interference pattern? Surely it is through observation/being watched?

If you watch the video and understand my question, then great. If my question doesn't make sense then ... thanks for reading and for the answers above already given.
A problem in representing an experiment using animation/simulation/model has a merit, which is simplifying the learning process by reducing the number of parameters/factors that influence the result, so students can be more focus on the targeted factor. But it also has its own cost, which sometimes overwhelms the benefits and missing the intended goals, or even showing the wrong results.
For example, I found some learning materials in youtube which shows light dispersion by a prism producing rainbow pattern, but the order of the colors is reversed.
I saw some problems in the video above. First, passing light through a single slit apparatus produces diffraction pattern, instead of a single bright line. Second, it doesn't show the actual method to observe the photon going through each slit. In some papers I've read regarding this experiment, they use polarization filters with different orientation for each slit (e.g. vertical for the left and horizontal for the right, or using clockwise and counter clockwise polarizers). So if we can detect the polarization state of the photon on the screen, we can conclude which slit it has passed through.
But of course we wouldn't get fringes on the screen, because lights with different polarization state don't produce destructive interference.
Logged
Unexpected results come from false assumptions.
 

Offline Harri (OP)

  • Sr. Member
  • ****
  • 106
  • Activity:
    0%
  • Thanked: 6 times
    • View Profile
Re: How are the results of the double slit experiment recorded?
« Reply #7 on: 04/07/2017 20:22:28 »
ah thanks, now it makes sense. It's difficult to articulate questions when you're a non scientist and not conversant in scientific language.
Logged
 
The following users thanked this post: chris

Offline chris

  • Naked Science Forum King!
  • ******
  • 7942
  • Activity:
    6.5%
  • Thanked: 273 times
  • The Naked Scientist
    • View Profile
    • The Naked Scientists
Re: How are the results of the double slit experiment recorded?
« Reply #8 on: 04/07/2017 23:59:21 »
Quote from: Harri on 04/07/2017 20:22:28
ah thanks, now it makes sense. It's difficult to articulate questions when you're a non scientist and not conversant in scientific language.
On the contrary - you asked an excellent and thought-provoking question.
Logged
I never forget a face, but in your case I'll make an exception - Groucho Marx - https://www.thenakedscientists.com/
 



  • Print
Pages: [1]   Go Up
« previous next »
Tags: interference pattern  / double slit experiment  / waves 
 

Similar topics (5)

What does Iain Stewart's "CO2 experiment" Demonstrate

Started by Pete RidleyBoard The Environment

Replies: 61
Views: 41427
Last post 05/05/2011 13:16:21
by JP
Blind and double blind?

Started by CorbeilleBoard Physiology & Medicine

Replies: 2
Views: 3775
Last post 01/11/2004 11:55:03
by Corbeille
Experiment suggests limitations to carbon dioxide 'tree banking'

Started by paul.frBoard The Environment

Replies: 1
Views: 3921
Last post 12/08/2007 03:01:25
by another_someone
Can NASA's STEREO Satellites confirm the Hafele and Keating Experiment?

Started by CliffordKBoard Physics, Astronomy & Cosmology

Replies: 2
Views: 4699
Last post 06/01/2012 10:03:10
by CliffordK
Can you recommend a low-cost catalyst for a hydrogen fuel cell experiment?

Started by Ls_minionBoard Chemistry

Replies: 1
Views: 3161
Last post 11/08/2013 01:00:46
by chiralSPO
There was an error while thanking
Thanking...
  • SMF 2.0.15 | SMF © 2017, Simple Machines
    Privacy Policy
    SMFAds for Free Forums
  • Naked Science Forum ©

Page created in 0.153 seconds with 56 queries.

  • Podcasts
  • Articles
  • Get Naked
  • About
  • Contact us
  • Advertise
  • Privacy Policy
  • Subscribe to newsletter
  • We love feedback

Follow us

cambridge_logo_footer.png

©The Naked Scientists® 2000–2017 | The Naked Scientists® and Naked Science® are registered trademarks created by Dr Chris Smith. Information presented on this website is the opinion of the individual contributors and does not reflect the general views of the administrators, editors, moderators, sponsors, Cambridge University or the public at large.