In science, ideas require experimental or observational validation.
These five ideas, although brilliant, simply disagreed with reality.
1.) The Steady-State Universe.
Was the Universe not merely the same throughout space, but across time?
The Cosmic Microwave Background’s discovery disproved it.
Its perfect blackbody spectrum proves its cosmic origin; it isn’t reflected starlight.
2.) Our Universe will someday recollapse.
Could gravitation defeat cosmic expansion, causing a Big Crunch?
No; dark energy exists, dominating the Universe’s expansion.
Unless it decays away — an evidence-free assertion — space will expand forever.
3.) The hot Big Bang began from a singularity.
An expanding, cooling Universe demands a smaller, hotter, denser past.
But arbitrary early temperatures are disallowed; the Cosmic Microwave Background sets stringent upper limits.
They’re inconsistent with a singularity; an inflationary stage came first.
4.) The speed of gravity is infinitely fast.
Do gravity and light propagate at identical speeds?
Gravitational wave and gamma-ray observations of 2017’s kilonova event settled the issue.
They mutually travel at indistinguishable speeds to ~1-part-in-1015; infinite speeds are disallowed.
5.) Dark matter is simply “normal matter” that’s invisible.
Gravitational properties of colliding galaxy clusters,
oscillatory features in the Cosmic Microwave Background,
large-scale galaxy clustering,
and Big Bang nucleosynthesis
all necessitate dark matter’s presence.
This article was reprinted with permission of Big Think, where it was originally published.