• Pixel-art sticker of Scaleon, personifying Cosmological Redshift, with the caption “Space Stretched My Wave.”

IndexRelativity & CosmosSticker

Scaleon

Cosmological Redshift Physics

\[1 + z = \frac{a_{\text{now}}}{a_{\text{then}}}\]
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$4.99 USD
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Meet Scaleon, a light wave who left a distant galaxy blue and arrived red because space stretched. Wavelengths stretch with the universe, so light from redshift 1 turns 500 nm into 1,000 nm. That is why the James Webb Space Telescope looks in infrared. Pixel-art kiss-cut sticker in 2, 3, 4 and 6 inches; equation, symbols and sources in the physics panel below.

Size
Surface

Flat $6 shipping worldwideMade to order, ships in 2–5 business days

Details

Size3″ × 3″

3″ × 3″ kiss-cut sticker.

Shipping

Flat $6 shipping on every order, worldwide, whatever's in it.

Delivery times & where we ship

Returns & replacements21 days

Every item is printed to order, so we can’t accept returns or exchanges for change of mind, or if you ordered the wrong size or colour.

Print defect, misprint, damage or the wrong item? We’ll send a free replacement, or a refund if you prefer. Report it within 21 days of delivery with a photo; no need to send it back.

Full refund & replacement policy

The physics

Meet Scaleon, a light wave who left a distant galaxy blue and arrived red, because space stretched along the way.

The universe is expanding. Cosmologists describe this with a scale factor, a, which tells how big distances are compared with today. As light crosses expanding space, its wavelength stretches by exactly the same factor as the space it travels through.

The redshift z obeys 1 + z = a_now/a_then. Light from a galaxy at z = 1 left when the universe was half its present size. A line emitted at 500 nm, in the blue-green, now arrives at 1,000 nm in the infrared.

The bigger the redshift, the longer ago the light set out. The cosmic microwave background has z ≈ 1,100, so the universe has stretched about 1,100 times since that light was released.

This is why the James Webb Space Telescope looks in infrared. Light from the earliest galaxies has been stretched far beyond the colours our eyes can see.

Equations

\[1 + z = \frac{a_{\text{now}}}{a_{\text{then}}}\]
SymbolMeaningUnit
\(z\) redshift \(\mathrm{dimensionless}\)
\(a_{\text{now}}\) scale factor when the light is received \(\mathrm{dimensionless}\)
\(a_{\text{then}}\) scale factor when the light was emitted \(\mathrm{dimensionless}\)

Sources

  1. OpenStax Astronomy 2e — The Age of the Universe
  2. Wikipedia — Redshift
  3. OpenStax Astronomy 2e — A Model of the Universe

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