Rowan Philp’s article, “Betting on the origin of the universe” (May 10), about different opinions on the origin and age of our universe, itself contains some differences with Liz Krusei’s article in March’s Astronomy, “How astronomers know the universe’s age”, and raises a question or two from me.
Philp says, “Planck adjusted our cosmic age to 13.8-billion”, but the age of the universe (13.77-billion years) had already been determined from calculations based on data from the cosmic microwave background (CMB) obtained by the Wilkinson microwave anisotropy probe (MWAP), not from the European Space Agency’s Planck mission.
The Planck mission has a resolution four times better than MWAP’s but the method used by the MWAP team – based on the wavelength of the CMB at the end of the universe’s extremely fast, initial period of inflation (375000 years) – is accurate within a percent or two and the Planck data is therefore able to finetune these results but not initially determine them.
Philp says Steven Hawking has a problem with the fact that the CMB temperature is constant throughout the universe and that “13.8-billion years is far too little time for the heat from the big bang explosion to have spread so evenly in such a vast space”, and further implies that the discovery of gravitational waves is necessary to prove the inflation theory. Surely the CMB expanded as part of space as the universe itself expanded; and, while gravitational waves may confirm the inflation theory, their discovery is surely not the only means of such confirmation? – David Douglas