Human only perceives 0.0035% of the electromagnetic spectrum with our eyes. This 0.0035% is known as visible light and comprises everything the human eye alone can detect in the universe. The range of visible light on the electromagnetic spectrum is so small that if you were to lay out the practical electromagnetic spectrum from Los Angeles to New York, the visible wavelengths would be nanometres across, small enough to pass through a surgical mask.
2. In 2008, the biggest ever gamma-ray burst was observed on earth. This violent cosmic explosion happened 7.5 billion light years away (halfway across the visible universe), yet was visible with the naked eye from the earth. Anyone who saw it was looking billions of years into the past with their eyes.
3. It is possible for humans to see infrared light pulses if the retina is exposed to two photons at once. Short pulses are perceived as green and long pulses are perceived as reddish.
4. Microwaves are "non-ionizing" radiation, meaning they have very little energy to damage DNA. So your microwave could give you a nasty burn (enough to kill you, even), but only in the same manner as your oven.
5. Purple as a color is similar to violet, but violet is a spectral color with its own wavelength on the visible spectrum of light whereas purple is a composite color that’s made by combining red and blue.
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The magenta color does not have its own wavelength. It's the product of combining red and blue light, which are on the opposite ends of the visible light spectrum, so our brains fill in the gap with what they think the color should be. So it is a biological artifact and doesn’t physically exist. Our brains are just telling us we are seeing "not green".
7. Gamma-ray bursts release more energy in the first couple of seconds than our Sun will ever release in its 10 billion year lifetime.
8. 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.
9. Ionizing radiation is used to preserve food and over 500,000 metric tons of foodstuffs are irradiated every year worldwide.
10. "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.
11Infrared And Ultraviolet
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.
12. 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."
13. 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.
14. 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.
15. 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.
Smoke detectors use gamma-ray radiation to detect smoke in the air.
17. You can see the invisible infrared light produced by your remote control if you point it into a digital camera (webcam, phone, etc.).
18. Since red wavelengths of light are absorbed in the first 10-20 feet of water, blood looks green below 50 feet of water.
19. 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.
20. Part of the static seen on old TV sets is caused by cosmic microwave background radiation from the Big Bang.
21Sun's True Color
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.
22. 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.
23. 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.
24. A gamma-ray burst from a neutron star has equivalent energy to 100 trillion nukes going off every second for 100 billion years.
25. 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.