Secrets of Energy: 40 Astonishing Facts About the Electromagnetic Spectrum

Li-Fi is a mode of visible light communication that can provide wireless internet access at data transfer rates of over 10 Gbps or 10,000 Mbps.

2. Ionizing radiation is used to preserve food and over 500,000 metric tons of foodstuffs are irradiated every year worldwide.

3. "555-Nanometer Wavelength Green" (which is similar to the shade of green used in "green screens") is the most visible color because it stimulates the most cones in the eye.

4. Infrared has less energy than the color red which is one side of the visible spectrum and ultraviolet has higher energy than violet which is on the other side of the spectrum.

5. The x-rays from an atomic bomb are so powerful, that they can compress lithium until it causes a fusion explosion, even without the shockwave. This kind of a fusion bomb is called a "Teller-Ulam" weapon, and it uses an atomic bomb as a "spark plug."

The main reason eyes see in the "visible spectrum" is because the earliest species to develop photosensitivity were aquatic, and only two specific wavelength ranges of electromagnetic radiation (blue and green visible light) can travel through water.

7. Very Low Frequency radio communications used by submarines diffract around mountains due to their long wavelength, and their use creates an artificial bubble around the Earth which protects it against solar flares and coronal mass ejections.

8. Low doses of ionizing radiation can be beneficial rather than detrimental in humans by stimulating the activation of cellular repair mechanisms that protect against disease. This phenomenon is known as Radiation Hormesis.

9. Smoke detectors use gamma-ray radiation to detect smoke in the air.

10. You can see the invisible infrared light produced by your remote control if you point it into a digital camera (webcam, phone, etc.).

Since red wavelengths of light are absorbed in the first 10-20 feet of water, blood looks green below 50 feet of water.

12. The Aurora Borealis (Northern Lights) and Aurora Australis (Southern Lights) also emit light rays outside the visible spectrum range, but the ultraviolet light gets absorbed by the atmosphere before it reaches us on the ground.

13. Part of the static seen on old TV sets is caused by cosmic microwave background radiation from the Big Bang.

14. The Sun is a white star. It appears yellow in the sky because the blue part of the visible spectrum is scattered away by the atmosphere. This is also the reason why we see a blue sky.

15. Red light does not reach ocean depths, so deep-sea animals that are red actually appear black and thus are less visible to predators and prey.

Blue wavelengths are the most potent portion of the visible electromagnetic spectrum for circadian regulation, and therefore avoiding blue light in the hours before bedtime helps improve sleep quality.

17. A gamma-ray burst from a neutron star has equivalent energy to 100 trillion nukes going off every second for 100 billion years.

18. Landsat 8 is a satellite designed by Nasa and the US Geological Survey. It can detect what minerals are hidden below the earth’s surface using near-infrared and short wave infrared spectral bands as well as a panchromatic band. This includes silver and gold. It is essentially the world's best metal detector.

19. The sky is blue due to the scattering of sunlight off molecules of the atmosphere. This is more effective at short wavelengths. Therefore the light scattered down to the earth at a large angle with respect to the direction of the sun's light is predominantly in the blue end of the visible spectrum.

20. X-rays are faintly visible to the dark-adapted eye when it is close to an x-ray source. It is not known why this occurs and it is seen by humans as a blue-grey glow.

The range of wavelengths that a human eye detects and that is used for photosynthesis are roughly the same (400nm to 700nm). Most of the other wavelengths are largely absorbed by ozone, carbon dioxide, and water.

22. Both pure spectral yellow light (Wavelength ~580nm) and the additive of red and green lights can stimulate us to perceive the same yellow color.

23. Peeling scotch tape in a vacuum produces radiation powerful enough to X-ray the human body.

24. When illuminated by ultraviolet rays from a black light, scorpions glow in unnatural neon blue color. UV light that hits them gets converted by proteins in their exoskeletons into the light of a blue hue, which is visible to the human eye.

25. When green lasers such as the ones used in Christmas displays get very cold, they stop emitting green and instead emit an invisible infrared beam that can cause eye damage.