Our ancestors asked a fundamental question – what is the universe made out of? (slide) They thought it was made out of earth, water, fire, and air, but if that’s what the world is made out of then what is light? You can’t grab light and put it in a bottle, you can’t touch it.
Light is everywhere and nowhere, we all experience it through our eyes, but the way it behaves has intrigued physicists for a long time. That’s why some of the greatest minds like Isaac Newton made the first complete studies on the nature of light. (slide) The author D. Kervick shows that Newton, for example, took white light from the sun, shone it through a prism and showed that all the colors of the rainbow would come out of white light. (slide) Newton thought that light was in some sense little tiny particles made up the stream called Light. So, we have the first theory of light. (Kervick)
(slide) However, there was another theory that said that Light was a wave, this guy named Thomas Young, that was able to show that white light had wave-like properties. Think of water, for example, if you throw a rock on a lake, you’ll see the water expanding in waves from the center, if you throw a second rock, the same thing will happen, but then you’ll see the waves meeting and creating an interference pattern. (slide) Well, Young showed this with light, he was able to get light, shine it through a small little pinhole, get another pinhole of light, and have this two waves collide with each other, and there it was, a beautiful interference pattern. (De Oliveira)
So, we now had two rival theories of light, the Newton’s particle theory of light, and Young’s wave-like theory of light. Einstein took this to the next level. (slide) What Einstein said, ‘Perhaps both are right’, Newton showed us that light has particle properties and Young showed that light has wavelike properties, and the two are different manifestations of the same thing. So, Einstein introduced the concept of particle and wavelike duality. (Strauss)
Now, the question is, what makes this visible light special? (slide) Well, nothing really, because invisible light has the same properties as visible light. X-ray, Radio waves, ultraviolet light behave like visible light but have a wavelength that our eyes cannot perceive. One of the reasons this might have happened is because eyes first evolved in water, which allows only the rainbow colors to filter through. (Blackwell, Manar)
Here is something very interesting, our universe gives off the full spectrum of light too. When you think of the night sky, you probably think of being able to see the bright stars with your own eyes, but that is just visible light. (slide) Which now you know it’s a tiny part of the full spectrum. To see the universe in its full spectrum we need to have the right eyes, and that means using special telescopes that can help us see beyond visible light. You’ve probably heard of the Hubble space telescope, and seen its beautiful pictures taken in visible and ultraviolet light, but you might not know that there are almost 20 space telescopes in orbit missions that can each see part of the full spectrum of light. With telescopes acting as our virtual eyes, both in space and here on earth, we can see some amazing things, and the coolest thing of all, no matter the wavelength or the energy, the light that we see in the distant universe, is the same thing that we can experience and study here on earth. Since we know the physics of how x-ray, ultraviolet or microwaves work here, we can study the light of a distant star or galaxy and know what kinds of things are happening there too.
So as you go about your daily life, think beyond what your eyes can and can’t see. Knowing just a little bit about the natural world can help you perceive the full spectrum around you all the time.
Works Cited
- BLACKWELL, Amy H., Manar, Elizabeth, ‘Electromagnetic Spectrum.’ UXL Encyclopedia of Science, 3rd ed., UXL, 2015. Science In Context, http://link.galegroup.com/apps/doc/CV2644300393/SCIC?u=viva2_nvcc&sid=SCIC
- DE OLIVEIRA, R. A.; PINTO MARTINS, A. F.; DA SILVA, A. P. B. Thomas Young e a teoria ondulatória da luz no início do século XIX: aspectos conceituais e epistemológicos. Caderno Brasileiro de Ensino de Física, [s. l.], v. 41, n. 2, p. 1–8, 2019.
- KERVICK, D. Hume’s Colors and Newton’s Colored Lights. Journal of Scottish Philosophy, [s. l.], v. 16, n. 1, p. 1–18, 2018.
- LERNER, K. Lee, Lerner, Brenda Wilmoth, ‘Light.’ The Gale Encyclopedia of Science, 5th ed., Gale, 2014. Science in Context,
- STRAUSS, D. F. M. Kontinuïteit en diskontinuïteit in die fisika en biologie. Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie, [s. l.], v. 36, n. 1, p. 1–9, 2017.
