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.
“How can the universe “expand”? There must be something beyond the expansion line.”
If there’s something beyond that line, then what is expanding no longer meets the definition of “universe”.
Hogwash!
Like saying that sunrise occurs un the western sky and sets in the eastern sky...
“Could we be wrong about everything?”
Liberals sure are.
would you happen to have any quick weblinks for some of that stuff? im apparently behind the curve
I am trying to remember the astronomer/mathematician guy that postulated the universe is not expanding but rotating or orbiting in sections so that from our perspective it looks to be expanding
Are you married?
Yes. And I do know the answer. ;)
“a simple test is to think about what direction gravity is going. if it has a direction there is also a space distortion, because there is no physical direction for time.”
It seems that way in 3 dimensions, but does that hold true in 4 dimensional spacetime? An asteroid that passes into the gravitational field of a star was traveling on a straight line geodesic before it came under the star’s influence and it is still traveling on that same straight line geodesic after it came under the stars’ influence. So where is the “direction” of gravity now?
I didn’t come up with this idea myself, so I may not be doing it proper justice. I actually cribbed it from Einstein, from one of the newspaper articles he wrote where he mentioned that he thought the interpretation of “space” itself being distorted in reality was a mistake, kind of as an offhand comment. Well, if spacetime is only composed of space and time, and the space isn’t being distorted, that would seem to leave time as the only possibility for what is being distorted.
Breathe in Breathe out
Constantly expanding and contracting...doing both. Everyone is right.
If a man is alone in the woods, and his wife isn’t around to hear him, is he still wrong?While on its face, your question would seem to be epistemological, it is moreso ontological -- until it goes to court, at which point it is merely alimoniological.
Love it when experts stumble.
It is a theory:
Frequency Decrease of Light
D.H.W. Reffer
ICPE, 313 Splai Unirii, Bucharest, Romania
Abstract
The phenomenon is so slow that its effect is undetectable in light emitted at distances as in our galaxy, but is significant in light coming from cosmological distances, hence the alias ”Cosmological Degeneration/Decay of Light”. An unprecedented case in physics is that the law governing the phenomenon results uniquely, through mathematical reasoning. As main consequences, it: solves Digges-Olbers’ paradox, thus making possible cosmology with infinite universe ; explains Hubble’s redshift (or cosmological redshift), in agreement with Hubble’s constant’s inconstancy; explains the Penzias & Wilosn CMB; explains the unexplained non-uniformity in CMB; replaces the Big-Bang theory/model/scenario. Two new predictions are made. Keywords: solving Digges-Olbers paradox; infinite universel; absolutely resting frame; Hubble constant inconstancy; tired-light model; replacing BigBang theory
Interesting read but they provide no mechanism for decreasing frequency.
The frequency of a photon changes due to relative velocity of the source and observer (red shift). This means that the energy of the photon has changed at the observer.
This theory says that if a photon loses energy after travelling great distances then either Plancks constant has to change or the frequency has to change.
Or it could be expansion of the universe and expansion of the fabric of space that causes all observed red shift. It is difficult to set up an experiment.
“It is a theory:”
It is a mathematical exercise, not a theory.
“This theory ...”
Repeat: Not a theory. No mention of a mechanism. Purely a mathematical exercise.
“Or it could be expansion of the universe and expansion of the fabric of space that causes all observed red shift. It is difficult to set up an experiment.”
At least three types of redshift occur in the universe — from the universe’s expansion, from the movement of galaxies relative to each other and from “gravitational redshift,” which happens when light is shifted due to the massive amount of matter inside of a galaxy.
This latter redshift is the subtlest of the three,”
https://www.space.com/25732-redshift-blueshift.html
Be assured that a walk through the ocean of most souls would barely get your feet wet....
“Or it could be expansion of the universe and expansion of the fabric of space that causes all observed red shift. It is difficult to set up an experiment.”
Experiment? It is quantified in our everyday life. GPS, speed detectors, Lidar, etc.
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