Barcodes of the Sky: Light Spectra Big Bang Evidence

If a light source moves away from an observer, then the waves are stretched; if the waves are stretched, their wavelength increases; if the wavelength increases, the light shifts toward the red end of the spectrum.

If the Big Bang occurred, then space itself has been expanding since that initial event; if space is expanding, then the universe cannot be static.

If a scientist measured the distances and redshifts of galaxies, and if he found a linear relationship between them, then that scientist was Edwin Hubble.

If the universe was once extremely hot and dense, then it must have cooled as it expanded; if it cooled, the original high-energy radiation would be stretched into the microwave range, which is the Cosmic Microwave Background.

If the galaxy is receding from Earth, then its light undergoes cosmological redshift; if redshift occurs, then the specific dark absorption lines will appear at longer (redder) wavelengths than they do on Earth.

If the Big Bang model is correct, then it must explain the expansion (redshift), the leftover heat (CMB), and the chemical makeup of the early universe (nucleosynthesis); items A, B, and C satisfy these requirements.

If a light source moves toward an observer, then the waves are compressed; if waves are compressed, the wavelength decreases; if the wavelength decreases, the light shifts toward the blue/violet end of the spectrum.

If the expansion of space is uniform, then a galaxy twice as far away has twice as much expanding space between us and it; if there is more expanding space, then the recession velocity must be proportionally higher.

If a source of waves moves relative to an observer, then the observed frequency changes; if this specific physical principle is applied to sound or light, it is defined as the Doppler Effect.

If the early universe emitted high-energy visible or UV light, and if space has expanded by a factor of about 1,000 since then, then the wavelengths must have stretched by that same factor into the microwave range.

If atoms absorb or emit specific amounts of energy, then electrons transition between discrete levels; if these transitions occur, they create distinct lines at specific wavelengths in a spectrum.

If the early universe was hot enough for fusion for only a few minutes, then only the simplest nuclei could form; if simplicity is the constraint, then Hydrogen (~75%) and Helium (~25%) are the resulting products.

If a dense, hot object emits light at all possible wavelengths in a range, then there are no missing frequencies; if there are no missing frequencies, the spectrum is described as continuous.

If the universe were shrinking, then galaxies would be moving toward us; if they move toward us, the light waves would compress (shorter wavelength) and show a blueshift.

If the Big Bang involves the expansion of the "fabric" of space, then the light is stretched as it travels through that expanding fabric; therefore, it is space expanding, not just galaxies moving through static space.

If the universe started in a hot state and expanded, then it must have cooled to a very low, predictable temperature; if we measure that temperature to be 2.7K everywhere, then it confirms the cooling prediction.

If light from a hot source passes through a cooler gas, then the gas atoms will soak up specific wavelengths; if those wavelengths are removed, the resulting display is an absorption spectrum.

If Hubble's Law (v = H0 * d) is correct, then velocity is proportional to distance; if a larger shift means a higher velocity, then a larger shift must also mean a greater distance.

If Penzias and Wilson were trying to remove "noise" from their radio antenna and found a persistent signal from all directions, and if that signal matched Big Bang predictions, then the discovery was indeed accidental.

If a gas is thin and hot, its atoms are far apart and emit light only at specific energy transitions; if it emits light only at specific wavelengths, it produces bright lines known as an emission spectrum.