All Keystone Science videos

Science

The Experiment that Disproved Reality

Start with the video, then use the science notes and recommended parts below to follow the idea behind the build.

Science

Watch on YouTube

How it works

What this project is testing.

The title is dramatic; the science is Bell inequality. The question is whether measurement results can be explained by hidden local instructions carried by particles all along.

Read more

The experiment tests correlations. Classical local realism sets a ceiling on how strong those correlations can be, while quantum mechanics predicts stronger ones. It does not mean everyday reality vanishes; it means nature is not locally realist in the simple EPR sense.

S \leq 2

The CHSH Bell bound for any local hidden-variable theory.

S_{QM} \leq 22

Quantum mechanics can exceed the local bound, up to Tsirelson limit.

Recommended parts

Products used in this project.

Affiliate links may earn Keystone Science a commission. Match ratings, values, sizes, polarity, and safety requirements to your own build before buying.

Rigol Digital Oscilloscope DS1054Z 50 MHz 4-Ch 1 GSa/s 24 Mpts 30,000 wfms/s UltraVision 7" 800x480 Intensity Display, 60,000-Frame Record/Playback, Serial Decode UART I2C SPI for Debug & Education

oscilloscopetest equipment

Rigol DS1054Z Digital Oscilloscope, 50 MHz, 4 Channel, 1 GSa/s

$349.004.7(724)

Good bench choice; budget scope alternatives may be cheaper but less durable.

ElectroCookie Large PCB Prototype Board Kit Solderable Breadboards for Electronics Projects Compatible for DIY Arduino Soldering Projects, Gold-Plated (6 Multi-Pack, Blue)

printed circuit board / PCBprototyping

ElectroCookie Large PCB Prototype Board Kit, Solderable Breadboards for Electronics Projects

4.8(111)

EDGELEC 120pcs Breadboard Jumper Wires 20cm Wire Length Optional Dupont Cable Assorted Kit Male to Female Multicolored Ribbon Cables

jumper wires / hookup wirewiring

120pcs Breadboard Jumper Wires, 20cm Dupont Cable Assorted Kit, Male to Female

$6.984.7(4,500)

AC Infinity MULTIFAN S3, Quiet 120mm USB Fan, UL-Certified for Receiver DVR PlayStation Xbox Computer Cabinet Cooling

fanelectromechanical

AC Infinity MULTIFAN S3, Quiet 120mm USB Fan

$14.994.7(37K)

WOWOONE Laser Diode 30Pcs 5V 650nm 5mW Mini Red Dot Laser Head, 6mm Outer Diameter Laser Module with Leads, for Arduino Laser DIY Electronics Projects, High-Stability Red Laser Diode

laser / laser pointeroptics

30pcs 5V 650nm 5mW Mini Red Dot Laser Diode Modules with Leads

$12.994.6(152)

Laser safety matters. Keep recommendations to low-power modules and add eye-safety warnings. Review requirements and safety guidance before buying.

Polarized Film Sheets 2 PCS 7.8x11.8inches/20x30cm Adhesive Polarizer Linear Polarizing Filter for Screen Educational Physics

polarizing filteroptics

Polarized Film Sheets, 2 PCS 7.8 x 11.8 inches, Adhesive Linear Polarizing Filter

$11.984.3(936)

MECCANIXITY Graphite Block Ingot Rectangle Graphite Electrode Plate Board 100x20x5mm for Melting Casting, Electrolysis Electroplating, Pack of 5

electrodeschemistry/electrical

MECCANIXITY Graphite Electrode Plate Board, 100x20x5mm, Pack of 5

$9.394.6(53)

Good functional match, but sparse Amazon review evidence. Review requirements and safety guidance before buying.

Apple 2025 MacBook Pro Laptop with Apple M5 chip with 10‑core CPU and 10‑core GPU: Built for AI, 14.2-inch Liquid Retina XDR Display, 16GB Unified Memory, 1TB SSD Storage; Space Black

computercomputing

Apple 2025 MacBook Pro Laptop with Apple M5 chip with 10-core CPU and 10-core GPU: Built for AI, 14.2-inch Liquid Retina XDR Display, 16GB Unified Memory, 1TB SSD Storage; Space Black

$1,538.304.7(107)

Preferred Apple laptop option for coding, editing, and project-control work.

NoCry Clear Safety Glasses for Men and Women with Anti-Fog and Scratch Resistant Wrap Around Lenses, Adjustable Temples and Nose Pads — ANSI Z87 Certified Protective Eyewear with 100% UV Shielding

safety glassessafety

NoCry Clear Safety Glasses with Anti-Fog and Scratch-Resistant Wraparound Lenses, ANSI Z87 Certified

$13.984.5(49K)

$Physics Optical Experiment Set Multifunction Reflector Refraction Triangular Prism Convex Lens Concave Mirror Dial Linear Light Source Teaching Demonstration Equipment for Teacher Student Education$

lensoptics

Physics Optical Experiment Set with Prism, Convex Lens, Concave Mirror, and Linear Light Source

$18.994.3(198)

Specialty optics may need size and focal-length review before publishing.

DEVMO DC 3V-6V to 400kV 400000V Boost Step-up Power Module High-Voltage Generator

high-voltage power supplypower

DEVMO DC 3V-6V to 400kV Boost Step-up High-Voltage Generator Module

$10.994.4(508)

Prefer low-current educational modules over mains-powered high-voltage supplies. Review requirements and safety guidance before buying.

Goupchn Universal P6100 Oscilloscope Clip Probes 100MHz with Accessories Kit 1X 10X 2 Pack

test probes / leadstest equipment

Goupchn Universal P6100 Oscilloscope Clip Probes, 100MHz, 1X/10X, 2 Pack

$13.994.7(126)

Project files

Prints, kits, and downloads.

Diagrams, printable files, kits, or companion downloads will appear here when they are ready to use.

Coming soon

Contact

Events, speaking, collaborations, and news.

Send the project name, outlet or audience, timing, location, and the context you want covered.

Email Keystone Science