From the night sky to the beginning of the universe
The effort to explain the motion of the planets turned into a journey that asked about Earth's place, about gravity and finally about the history of the universe itself.
This page delivers no verdict; it presents claims and evidence with their sources. No theory in science is absolute.
Stop 1c. 150Astronomy and cosmologyText / work
Ptolemy's Almagest and the geocentric model
Ptolemy's Earth-centred model predicted planetary positions with usable accuracy for some 1,400 years.
Claims, evidence and sources →Stop 2c. 1437Astronomy and cosmologyEvent / publication / experiment
Ulugh Beg and the Samarkand Observatory
At Ulugh Beg's observatory in Samarkand, star positions were measured again with great care.
Claims, evidence and sources →Stop 31543Astronomy and cosmologyText / work
Copernicus and the heliocentric model
Copernicus put the Sun at the centre. At first the model did not predict better, but it proposed a different way of looking at the sky.
Claims, evidence and sources →Stop 41609Astronomy and cosmologyText / work
Kepler's laws
Kepler inferred from Tycho Brahe's observations that the orbits are ellipses.
Claims, evidence and sources →Stop 51687PhysicsText / work
Newton's Principia
Newton explained the falling apple and the orbits of the planets with the same laws.
Claims, evidence and sources →Stop 6November 1915PhysicsIdea / theory / claim
General relativity
Einstein redescribed gravity as the curvature of spacetime; the theory allowed for black holes and an expanding universe.
Claims, evidence and sources →Stop 71927Astronomy and cosmologyIdea / theory / claim
The beginning of the universe and the Big Bang
Lemaître proposed that the universe is expanding from a hot, dense beginning. The views of religions and of other cosmological models on the beginning sit side by side in this node.
Claims, evidence and sources →Stop 81933Astronomy and cosmologyQuestion
Dark matter
Galaxies rotate faster than their visible matter can explain. Unseen matter, or modified gravity? The question is open.
Claims, evidence and sources →Stop 91998Astronomy and cosmologyQuestion
Dark energy and accelerating expansion
The expansion of the universe was found to be accelerating; what drives it is unknown.
Claims, evidence and sources →Stop 10April 2019Astronomy and cosmologyEvent / publication / experiment
The first image of a black hole
In 2019 the first image of the ring of light around a black hole was published.
Claims, evidence and sources →Stop 11December 25, 2021Space explorationEvent / publication / experiment
The James Webb Space Telescope
The James Webb Space Telescope sees galaxies from a few hundred million years after the Big Bang and tests the models again.
Claims, evidence and sources →
Other journeys
- The story of the atom · 7 stops
- The journey of medicine · 8 stops
- From counting to artificial intelligence · 11 stops
- Reason and revelation: a debate in Islamic thought · 9 stops
- Views on the origin of living things · 11 stops
- From brain to mind · 9 stops