Warm Emptiness Instead of Dark Energy ✎ express
In the standard cosmological model ΛCDM, galaxies recede under the pressure of dark energy — an invisible spring. However, different methods of measuring the expansion rate give different numbers, as if the ruler's scale is off. This discrepancy was noticed by Edwin Hubble almost a century ago.
A new study proposes an alternative: replace the spring with heat. Emptiness is not empty — according to calculations by Stephen Hawking and Gary Gibbons, the boundary of the visible world, the cosmic horizon, has a tiny temperature. This heat presses from within, and the wider the horizon, the higher the temperature. Expansion becomes a thermal breath: an exhalation of heat expands space.
Unexpected twist: the Universe is not cooling but heating up. The horizon's thermal energy grows, spurring the outward rush. Thus, there's no need for a mysterious constant — the heat of its own boundaries is enough. Big Bang turns out not to be a push from the past, but the kindling heat of the present.
The temperature of the cosmic horizon is about 10⁻²⁹ Kelvin — billions of times colder than the coldest point ever created by humans.
Science fiction writers sometimes talk about a 'warm Universe' with an inner fire — here it gets a scientific basis.