Discover How We Came to Know the Cosmos

Light & Matter

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Space & Time

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Electromagnetic wave

Diagram of an electromagnetic wave. This is composed of a magnetic wave and an electric wave, which are perpendicular to each other.

Original picture with caption
Image credit: modified by Helen Klus, original image by LennyWikidata
Licence: CC BY-SA 4.0
Link to high-res image

Superposition

Diagram showing that two waves of the same phase combine to produce waves of twice the amplitude. Waves that are completely out of phase, will cancel out, producing a flat line.

Original picture with caption
Image credit: modified by Helen Klus, original image by Haade/Wjh31/Quibik
Licence: CC BY-SA 4.0
Link to high-res image

Spectral lines

Diagram showing that a continuous spectrum is created if light comes directly from a star. Absorption lines are created if the light travels through a cloud, and an emission spectrum from light directly emanating from the cloud.

Original picture with caption
Image credit: modified by Helen Klus, original image by Magnus Manske/Jhausauer
Licence: CC BY-NC-SA 4.0
Link to high-res image

Chirality

Diagram showing chiral and non-chiral objects. Chiral objects, like handprints and footprints, cannot be superimposed on their mirror images.

Original picture with caption
Image credit: modified by Helen Klus, original images by George Hodan, Karen Arnold, and Piotr Siedlecki
Licence: Public domain
Link to high-res image

Speed of light

Diagram showing apparatus used to determine the speed of light.

Original picture with caption
Image credit: modified by Helen Klus, original image by Rhodesl
Licence: Public domain
Link to high-res image

Multiplying x by a constant

Plot of cos(x), cos(1/2x), and cos(2x).  In the first plot, the wavelength is 360°. In the second plot, the wavelength is twice as long, and in the third it is half as long.

Original picture with caption
Image credit: Helen Klus
Licence: CC BY-NC-SA 4.0
Link to high-res image

Last updated on 25th January 2018 by Dr Helen Klus

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The Star Garden is a science news and science education website run by Dr Helen Klus.

How We Came to Know the Cosmos covers the history of physics focusing on space and time, light and matter, and the mind. It explains the simple discoveries we made in prehistoric times, and how we built on them, little by little, until the conclusions of modern theories seem inevitable. This is shown in a timeline of the universe.

The Star Garden covers the basics for KS3, KS4, and KS5 science revision including SATs, GCSE science, and A-level physics.