ESPAÇO
Energia negra do universo pode estar a enfraquecer
March 20, 2025 -
A força misteriosa, que se pensa impulsionar a expansão do universo,
pode estar a enfraquecer, alterando o entendimento dos cientistas
e sugerindo que o universo pode acabar com um Big Bang inverso.
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According to the standard model of cosmology, since the explosive birth of the universe 13.8 billion years ago in the Big Bang, the universe has been expanding, driven by an unknown force, so-called dark energy
As the universe expands, galaxies are carried farther apart; the farther they are from each other, the faster they separate. If expansion of the universe were slowing, light from faraway supernovae should appear brighter than if expansion was constant, but instead, they are even fainter than expected, meaning expansion is actually speeding up.
However, dark energy was assumed to be a constant but new measurements show it appeared to reach a peak when universe was about 70% of its current age and it is now about 10% weaker. Expansion is still accelerating, but rate of acceleration decreasing.
If dark energy is constant, stars will eventually become too far apart to see, but if it keeps decreasing - or even becomes negative - the universe could end in a reverse big bang or Big Crunch.
- Dark energy: mysterious cosmic force appears to be weakening, say scientists (The Guardian)
- ‘More Than a Hint’ That Dark Energy Isn’t What Astronomers Thought (New York Times)
- How will the universe end? Scientists narrow it down to two scenarios (The Independent)
- The Dark Energy Spectroscopic Instrument (DESI)
- Cosmic dark energy may be weakening, astronomers say, raising questions about the fate of the universe (Phys.org)