Posted on 07/26/2023 10:33:46 AM PDT by MtnClimber
Dismantling the belief in a static universe, Edwin Hubble's revolutionary observations in the 1920s laid the groundwork for our understanding of a continually expanding cosmos. However, we must seek to reconcile this theory with observations that are consistent with a non-expanding universe, writes Tim Anderson.
You have been taught that the universe began with a Big Bang, a hot, dense period about 13.8 billion years ago. And the reason we believe this to be true is because the universe is expanding and, therefore, was smaller in the past. The Cosmic Microwave Background is the smoking gun for the Big Bang, the result of a reionization of matter that made the universe transparent about 300–400,000 years after the Big Bang.
How did we go from Einstein modifying his equations to keep the universe static and eternal, which he called the biggest blunder of his life, to every scientist believing that the universe had a beginning in 10 years? It all started with astronomer Edwin Hubble using the most powerful telescope at the time on Mount Wilson in California. At the time, in the 1920s, scientists believed that the Milky Way galaxy was the totality of the universe. Objects in the night sky like Andromeda that we now know are galaxies were called “nebulae”.
Looking at these objects, however, Hubble knew how bright particular stars called Cepheid variables were supposed to be. Knowing how bright they were supposed to be meant that he could tell how far away they were. He found to his surprise that Andromeda and Triangulum had Cepheid variables that were too far away to be inside the Milky Way. They weren’t nebulae. They were galaxies.
Hubble’s discoveries, made in 1924, merited a short column on page 6 of the New York Times. In that article, “Dr. Hubbell” was said to have shown that nebulae are in fact “island universes”. The concept was so new that they weren’t even recognized as galaxies. Hubble was able to estimate distances for his newly discovered galaxies. His estimates were off by about a factor of 7 but proportionally correct. Other scientists such as Vesto M. Slipher, had been busy, since 1912, measuring how fast the galaxies he identified were moving towards or away from us by measuring their redshift.
The way you measure redshift uses a concept from atomic theory called spectroscopy. Basically, stars contain elements that absorb light at specific wavelengths. These are patterns of missing wavelengths in the spectrum of the light called absorption spectra. These patterns show up because the atoms contain electrons that absorb photons with particular frequencies. When the photon strikes the atom, the electron absorbs it and moves to a higher orbital, but only if it has the exact frequency needed for that electron. Otherwise, no absorption happens. This property can be used to determine what things are made of by exposing them to light and measuring their emissions. It can also be used to make lasers.
Spectrum of the star Altair from NASA, ESA, Leah Hustak (STScI).
In astronomy, it is how we determine how fast objects are moving towards or away from us because of something called the Doppler effect. If something is moving away from us, the wavelengths of light coming from that object will be stretched out which makes them longer and lower frequency. This shifts the absorption spectrum to the right in the above picture and so is called redshift since the right side is red. If the object is moving towards us, then it will be shifted to the blue side and so is called blueshift. The same thing happens with sound which is why a siren has a higher pitch as an ambulance moves towards you and a lower pitch when it moves away from you.
Since we know what the frequencies in the absorption spectrum are supposed to be for particular elements and we can, by the pattern and what we know about stars, identify what those elements should be. We can determine how redshifted stars and galaxies are. When Hubble looked at all these new galaxies he had identified, he made a correlation between their velocity based on redshift and their distance based on the Cepheid variables. It turns out that these were linearly correlated. In other words, the further away a galaxy was, the faster it moved away from us. You can make a graph with speed on the vertical axis in km/s and distance on the horizontal axis in Megaparsecs (about 3.26 million lightyears) and you will find that it makes a line.
Hubble identified the slope of this line as a universal constant which we now know as the Hubble constant. His value was about 500 km/s/Megaparsec. If you correct for his factor of 7 error in distance, this falls within the currently accepted value of 68–74 km/s/Megaparsec. Alexander Friedmann in 1922 and Fr. George Lemaître independently in 1927 had used Einstein’s field equation to predict that the universe should be expanding (or shrinking). Combining their results with Hubble’s observations and the successful demonstration of the correctness of Einstein’s equations within the Solar System, scientists concluded that the universe was expanding.
Not everyone was happy about this conclusion. That included Hubble himself. Hubble disagreed with the interpretation of his data believing that redshifts might not be related to velocity at all and he criticised the popularity of the expanding universe theory, saying in the Journal of the Royal Astronomical Society in 1937:
The interpretation of red shifts by the theory of the expanding universes is so plausible and so widely current that, in making a delicate test of the theory, it is desirable to push uncertainties in the favourable direction before admitting a discordance.
He had good reason to believe in a discordance because, based on his data, the universe would have been younger than the Earth, too small and dense by far, with a “closed” geometry implying it should fall back in on itself. This turned out to be wrong because Hubble had vastly underestimated the distances to the galaxies he had observed. The universe was actually far older and less dense than he believed.
Oh my gosh, the settled science isn’t settled? Who would have guessed a theory might just be a...well, theory.
“We” who?
I read the Metaxas biography of Dietrich Bonhoeffer. I highly recommend it.
“One of the craziest things over these last few crazy years has been watching physics at both ends (subatomic and cosmological) completely fall apart”
??The Standard Model is more robust and confirmed than ever.
It either is or it isn’t......................
The physics hasn’t fallen apart. The injection of junk science has totally corrupted the integrity of physics.
LOL
Even if he's wrong, his life is peaceful.
We only Guess or make things up
Exactly. But there are measurements/theories that indicate each possibility. So clearly there are some fundamental things that are not understood. The biggest IMO is "what is black matter?" One big problem is that, as humans, we only have a blip in time to measure movement.
That’s “God only Knows” by the Beachboys.
If you make things up, you can always make something up to make it the fault of your political enemy.
Any group that relies on “matter” that cannot be detected except by it’s gravitational effect to make it’s theories work is not a group that can be taken seriously. Especially a group that celebrates the opening of its biggest project with some strange Hindu ceremony.
Come on...This is simple if you understand that the universe is nothing more that an illusion. One only perceives that it exists at all.
If you take the current physics model of the atom and try to use it in the chem department, it doesn’t work. And vice versa. Both models have a lot of workability. But both ultimately are false.
Um, no. Follow evidence to form the most logical conclusion based on what we know so far.
It’s not just made up.
In a universe as big as ours, some objects are coming at us in our direction and some are going away from us in the opposite direction.
Objects within galaxies would be doing both, as the spinning galaxy would have half it’s mass, figuratively speaking, coming at us and half spinning away from us.
Gravity Waves add another factor.
If a Gravity Wave passes between us and the object, Space would then expand and contract as the wave passes, which might take a million years. The Red Shift would then shrink then expand accordingly.
I think there is more we don’t know than what we do..........................
Far out man.
Puff, puff, pass.
We have had thousands of years of scientific advancements and if we think we are done we are just kidding ourselves.
Never will we be done.
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