The Fascinating Expansion of the Universe
One of the most intriguing phenomena in the universe is its expansion since the Big Bang. Join us as we explore the mind-boggling concept of the universe expanding with acceleration.
There is nothing wrong with the concept of the universe expanding and accelerating but this is because we are looking at it relatively. Hence, if the universe initially inflated, perhaps at the speed of light, then we would see it expanding at the speed of light (if we could detect that) at the furthest point relatively? That means that the creation of space in our direction has got slower and slower until now. It's just relativity! Hence we are in the newly created 'space' and the universe appears to be expanding away from us NOW but also relatively accelerating away from us.
Expansion Measurement
Redshift is a term used when astronomical objects are moving away from us and the light coming from those objects stretches out. By measuring the spectrum of light from a distant galaxy and observing the Hydrogen line position, Hubble found that the Hydrogen line in distant galaxies had shifted to a different position compared to more local measurements. This is known as the Redshift because the further galaxies are moving away faster causing the light colour to move to red due to the doppler effect.
Astronomer Edwin Hubble confirmed that the universe was expanding in 1929 using these observations made by his associate, astronomer Milton Humason. Humason who measured the redshift of spiral galaxies.
Cepheid stars are also used to measure distances. All Cepheid stars with a certain period (a Cepheid’s period is the time it takes to go from bright, to dim, and bright again) have the same absolute magnitude, or luminosity – the amount of light they put out. Leavitt measured these stars and proved that there is a relationship between their regular period of brightness and luminosity. Leavitt’s findings made it possible for astronomers to use a star’s period and luminosity to measure the distances between us and Cepheid stars in far-off galaxies (and our own Milky Way).
Among the methods astronomers have found to measure the expansion rate of the local universe, the Hubble constant, surface brightness fluctuations is potentially one of the most precise. Scientists have now published the first good SBF estimate of the Hubble constant, pegging it at 73.3 km/s/Mpc: in the ballpark of other measurements of the local expansion, including the gold standard using Type Ia supernovae. The new estimate highlights the mismatch with estimates from the early universe.
Universe is NOT "isotropic"
Until recently, one fundamental acceptance of cosmology is that everything looks the same in all directions if you look over large enough distances, i.e. "isotropic". However, a new study using data from NASA's Chandra X-ray Observatory and ESA's XMM-Newton is challenging that basic notion.
Astronomers using X-ray data from these orbiting observatories studied hundreds of galaxy clusters, the largest structures in the universe held together by gravity, but the properties they display differ across the sky. Hence the Universe is NOT "isotropic" meaning it is NOT the same in all directions... The results gave the researchers apparent expansion speeds across the whole sky — revealing that the universe appears to be moving away from us faster in some directions than others.
Challenging the Logic of Expansion
While the expansion of the universe is widely accepted, have you ever questioned its logic? At our website, we encourage critical thinking and exploration. Let's push the boundaries of conventional understanding and ponder alternative reasons for the expansion of our vast universe.
The universe that we see is thought to be 'expanding' and that objects further away are apparently relatively travelling away from us at a faster speed than nearer objects (hence red shift phenomena). Remember - space AND matter are constantly being created by quantum fluctuations.
The edge of the universe is actually the so-called 'Big Bang'? Which came from a single point (a singularity?). So how can that be expanding? What is it expanding into? Surely not an infinite 'space' because we have just established it must be the so-called 'Big Bang'?
'Space' has actually been shown to be vacuum energy due to quantum fluctuations, so the newly created expansion must be from the the furthest point towards us? That means we live in newly created 'space'. Although you have to be aware that it is at this point in time we are living and this speck of time is only a minute part of the lifetime of the universe.
"Einstein was not comfortable with the notion of an infinite Universe that contained a finite amount of matter. He believed that a spatially bounded, and thus finite, Universe was a much more natural choice from the point of view of general relativity......"
...Pursuit of the universe's expansion rate began in the 1920s with measurements by astronomers Edwin P. Hubble and Georges Lemaître. In 1998, this led to the discovery of "dark energy," a mysterious repulsive force accelerating the universe's expansion. In recent years, thanks to data from Hubble and other telescopes, astronomers found another twist: a discrepancy between the expansion rate as measured in the local universe compared to independent observations from right after the big bang, which predict a different expansion value.
The cause of this discrepancy remains a mystery. But Hubble data, encompassing a variety of cosmic objects that serve as distance markers, support the idea that something weird is going on, possibly involving brand new physics...
...Right now, it looks like cosmology is at a tipping point. Will the James Webb telescope resolve the issue by revealing new physics?
For the past few years, a series of controversies have rocked the well-established field of cosmology. In a nutshell, the predictions of the standard model of the universe appear to be at odds with some recent observations.
There are heated debates about whether these observations are biased, or whether the cosmological model, which predicts the structure and evolution of the entire universe, may need a rethink. Some even claim that cosmology is in crisis. Right now, we do not know which side will win. But excitingly, we are on the brink of finding that out.
To be fair, controversies are just the normal course of the scientific method. And over many years, the standard cosmological model has had its share of them. This model suggests the universe is made up of 68.3% "dark energy" (an unknown substance that causes the universe's expansion to accelerate), 26.8% dark matter (an unknown form of matter) and 4.9% ordinary atoms, very precisely measured from the cosmic microwave background — the afterglow of radiation from the Big Bang.
It explains very successfully multitudes of data across both large and small scales of the universe. For example, it can explain things like the distribution of galaxies around us and the amount of helium and deuterium made in the universe's first few minutes. Perhaps most importantly, it can also perfectly explain the cosmic microwave background.
This has led to it gaining the reputation as the "concordance model". But a perfect storm of inconsistent measurements — or "tensions" as they're known as in cosmology — are now questioning the validity of this longstanding model...
See Expansion Details below - click on 'Explore New Understandings'
Is Expansion an Illusion?
The expansion of the universe could be a mirage, a potentially controversial new study suggests. This rethinking of the cosmos also suggests solutions for the puzzles of dark energy and dark matter, which scientists believe account for around 95% of the universe's total energy and matter but remain shrouded in mystery.
The novel new approach is detailed in a paper published 29 June 2023 in the journal Classical and Quantum Gravity, by University of Geneva professor of theoretical physics Lucas Lombriser.
...More recently, scientists have found evidence that the universe's expansion isn't fixed, but is actually accelerating faster and faster. This accelerating expansion is captured by a term known as the cosmological constant, or lambda....
In Lombriser's mathematical interpretation, the universe isn't expanding but is flat and static, as Einstein once believed. The effects we observe that point to expansion are instead explained by the evolution of the masses of particles — such as protons and electrons — over time.
In this picture, these particles arise from a field that permeates space-time. The cosmological constant is set by the field's mass and because this field fluctuates, the masses of the particles it gives birth to also fluctuate. The cosmological constant still varies with time, but in this model that variation is due to changing particle mass over time, not the expansion of the universe....
Curious to Learn More?
If you're intrigued by the expansion of the universe and eager to explore alternative perspectives, don't hesitate to reach out to us. Our website is dedicated to educating and inspiring individuals about the mysteries of the cosmos. Let's embark on a cosmic journey together!
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