The Universe is accelerating
For a while now, astrophysicists have known that our Universe is expanding, and accelerating. And much like the surface of a rubber balloon getting inflated, space is getting bigger, and bigger, and bigger…
Two experiments have shown a large discrepancy between theory and observation. The new astronomical measurements obtained by NASA and the European Space Agency (ESA) suggest that the Universe is in fact expanding quicker than the laws of Physics should allow.
Scientists have established that this discrepancy is not the result of an accident during the measurement process, but rather a fact of our unstable Universe – which is expanding 9% faster than theory predicts it should according to theoretical computer models.
Intergalactic Space is Expanding
Like dots pencilled on the surface of a party balloon, space between galaxies itself is stretching.
Imagine that you are an object on the surface of a balloon and everything is moving away from you because the balloon is getting bigger. That’s all well and good, but the balloon itself is expanding into a dimension that one, on the surface, does not directly experience.
Nevertheless, astronomers can observe this cosmological expansion by measuring the light from distant galaxies and supernovae, which turns redder as it passes through this stretching space!
A Shift in Colour
By measuring this “redshift“, scientists can calculate the rate of expansion – but astronomers find a baffling discrepancy between what science predicts and what it actually observes.
It follows that…
If the wavelength of a line in the light spectrum of a galaxy or a supernova is measured by observation, then compared with the wavelength of the same spectral line, as measured in a laboratory, the red-shift or blue-shift of the galaxy can be calculated.
Note The redshift/blueshift is related to the speed of motion of the observed astrophysical object. It can also be converted into the speed of recession or approach of that galaxy.
Reviewing the Cosmological Constant
Beyond a Plausible Level of Chance
A Baffling Astronomical Discrepancy
The new value determined by measurements made with the Hubble Space Telescope was updated to:
H0 = 74.03 ± 1.42 km s−1 Mpc−1.
Precision HST photometry of Cepheids in the Large Magellanic Cloud (LMC) reduced the uncertainty in the distance to the LMC from 2.5% to 1.3%.
The revision increases the tension with CMB measurements to the 4.4σ level (P=99.999% for Gaussian errors), raising the discrepancy beyond a plausible level of chance.
The 8.7% difference between these values is a disagreement of 3.6σ (p < 0.05%). The Hubble tension is bolstered by independent measurements of H0 at different redshifts which suggest a schism between the early and late universe.
“This mismatch has been growing and has now reached a point that is really impossible to dismiss as a fluke. This disparity could not plausibly occur just by chance.”
The Universe Expands and Expansion is Accelerating
The astrophysical researchers involved used the largest sample to date of spectroscopic SN Ia distances and redshifts.
Professor Riess underscores:
“This is not just two experiments disagreeing. We are measuring something fundamentally different.”
“One is a measurement of how fast the Universe is expanding today, as we see it. The other is a prediction based on the physics of the early Universe and on measurements of how fast it ought to be expanding.”
“If these values don’t agree, there becomes a very strong likelihood that we’re missing something in the cosmological model that connects the two eras.”
Among the theories that could explain this mismatch are those which suggest the existence of concepts such as dark energy, dark matter and dark radiation.
These hypothetical forms of matter or energy in the Universe have been proposed by scientists as a way to resolve these puzzling mathematical models.
Riess and his team do not yet have an answer to this “vexing problem”, but they will go on using the Hubble Space Telescope to fine-tune their measurements in observing supernovae and investigate how quickly space is expanding.
The goal of the researchers is to decrease the uncertainty to 1% which should help astrophysicists identify the cause of this accelerating expansion – whether dark matter, energy, or perhaps…
Something completely different?