- Why was the nature of the Andromeda nebula such a contested question in 1913?
Cosmic Microwave Background
The relic radiation from the early universe.
- What was the Great Debate of 1920, and what were the two competing views of the Andromeda nebula?
- What later astronomical discoveries grew out of the field of radio astronomy that Jansky's antenna founded?
- What temperature did Alpher and Herman predict for the universe's leftover radiation, and when was it confirmed?
- How long did it take before the cosmic microwave background prediction was actually observed?
- What evidence eventually disproved the steady-state model?
- What were Penzias and Wilson actually trying to do with their horn antenna when they found the mysterious hiss?
- What mundane explanations did Penzias and Wilson rule out before accepting the noise was real?
- How was Robert Dicke's team at Princeton already prepared to explain the exact signal Penzias and Wilson had found?
- How old is the cosmic microwave background radiation, and what does it reveal about the early universe?
- What did Gamow, Alpher, and Herman predict in 1948 about radiation left over from the early universe?
- How did Penzias and Wilson accidentally detect the cosmic microwave background in 1964?
- What made Penzias and Wilson's microwave antenna hiss suspicious enough to investigate for years?
- How does a uniform 2.7 Kelvin glow across the whole sky count as evidence for the Big Bang?
- Why did Penzias and Wilson initially blame pigeons for the noise in their antenna?
- What two questions about the cosmic microwave background was COBE specifically designed to answer?
- Why did the small temperature anisotropies detected in 1992 matter for explaining how galaxies formed?
- Why did it take until 2006 for Mather and Smoot to receive the Nobel Prize for the COBE results?
- What is the cosmic microwave background, and when was it formed?
- What age for the universe did WMAP's 2003 data establish, and how precise was that estimate?
- What were the measured proportions of ordinary matter, dark matter, and dark energy in the universe?
- What did the WMAP data confirm about cosmic inflation and the geometry of space?
- What did COBE's measurements of the cosmic microwave background confirm about the Big Bang?
- Why were the tiny temperature fluctuations COBE detected so significant for understanding galaxy formation?
- How cold is the afterglow of the Big Bang today, and why has it cooled so much?
- What did the BICEP2 team claim to have detected in the cosmic microwave background in March 2014?
- How did polarised galactic dust end up mimicking the signature of primordial gravitational waves?
- What role did the Planck satellite's joint analysis play in retracting the BICEP2 claim?
- What theoretical framework did James Peebles build to explain dark matter, dark energy, and the cosmic microwave background?