Re: Čudeži in znanost
Objavljeno: 31.10.2021 20:57
Surprise: the Big Bang isn’t the beginning of the universe anymore
We used to think the Big Bang meant the universe began from a singularity. Nearly 100 years later, we're not so sure.
But physically, when we looked closely enough, we found that the universe told a different story. Here’s how we know the Big Bang isn’t the beginning of the universe anymore.
The quantum fluctuations that occur during inflation get stretched across the universe, and when inflation ends, they become density fluctuations. This leads, over time, to the large-scale structure in the universe today, as well as the fluctuations in temperature observed in the CMB. New predictions like these are essential for demonstrating the validity of a proposed fine-tuning mechanism. (Credit: E. Siegel; ESA/Planck and the DOE/NASA/NSF Interagency Task Force on CMB research)
Lastly, and perhaps most importantly, we can no longer speak with any sort of knowledge or confidence as to how — or even whether — the universe itself began. By the very nature of inflation, it wipes out any information that came before the final few moments: where it ended and gave rise to our hot Big Bang. Inflation could have gone on for an eternity, it could have been preceded by some other nonsingular phase, or it could have been preceded by a phase that did emerge from a singularity. Until the day comes where we discover how to extract more information from the universe than presently seems possible, we have no choice but to face our ignorance.
The Big Bang still happened a very long time ago, but it wasn’t the beginning we once supposed it to be.
vir
We used to think the Big Bang meant the universe began from a singularity. Nearly 100 years later, we're not so sure.
But physically, when we looked closely enough, we found that the universe told a different story. Here’s how we know the Big Bang isn’t the beginning of the universe anymore.
The quantum fluctuations that occur during inflation get stretched across the universe, and when inflation ends, they become density fluctuations. This leads, over time, to the large-scale structure in the universe today, as well as the fluctuations in temperature observed in the CMB. New predictions like these are essential for demonstrating the validity of a proposed fine-tuning mechanism. (Credit: E. Siegel; ESA/Planck and the DOE/NASA/NSF Interagency Task Force on CMB research)
Lastly, and perhaps most importantly, we can no longer speak with any sort of knowledge or confidence as to how — or even whether — the universe itself began. By the very nature of inflation, it wipes out any information that came before the final few moments: where it ended and gave rise to our hot Big Bang. Inflation could have gone on for an eternity, it could have been preceded by some other nonsingular phase, or it could have been preceded by a phase that did emerge from a singularity. Until the day comes where we discover how to extract more information from the universe than presently seems possible, we have no choice but to face our ignorance.
The Big Bang still happened a very long time ago, but it wasn’t the beginning we once supposed it to be.
vir