ATOMS · LIGHT · DISCOVERY
Reading the unreachable.
How can light reveal what a distant star is made of?
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H01 · species
Water is not hydrogen gas
Why does water behave differently from hydrogen gas?
H02 · isotope
Identity and isotopes
What can change while hydrogen stays hydrogen?
H03 · transition
Atomic transitions and light
Why does an atom emit particular colors?
H04 · spectrum
Operate a laboratory spectrometer
When do two nearby lines become distinguishable?
H05 · telescope
A spectrum from the sky
How confidently can you identify a distant ingredient?
H06 · timeline
A cosmic ingredient
How does early-universe hydrogen connect to water today?