Do they mean "is" or "was"

Sep 5, 2021
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All the experts say that the universe IS expanding and the expansion is accelerating. They know because they've carefully measured galaxies from thousands of light years back in time to billions of light years back in time.
Why do they say "is" expanding when "was" seems more accurate.
I don't see any way they can tell what the universe is doing right now. What is the basis for saying the universe "is" doing anything?
 
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rod

Oct 22, 2019
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My answer, assumption using certain physics and math :) An example is the size of the universe when the CMBR first appeared said to be about 380,000 years after the BB event. Cosmology calculators show the angular size diameter to be some 80 or 82 million light years across. Today, the CMBR redshift is said to be some 1100 or so. What size is the universe today in the BB model? At least 93 billion light years in diameter so in nearly 13.8 billion years, the universe went from 80 or 82 million light years across to 93 billion today :) https://phys.org/news/2021-03-myths-big.html, Five myths about the Big Bang 22-Mar-2021, "That which we call the observable universe is a bubble surrounding us that is 93 billion light-years in diameter."

I use these cosmology calculators when looking at redshifts of objects presented and 3D space expanding. Cosmology Calculators (caltech.edu) , and Cosmology calculator | kempner.net

In astronomy there is only one direct method for measuring distances to stars. Stellar parallax but that is limited to, today about 8,000 light years based upon Gaia stellar parallax measurements. Measuring the universe size when the CMBR first appeared to present size said to be some 93 billion light years across is an interesting topic to explore using the scientific method, e.g. independent methods and verification other than calculated redshifts for the early CMBR (a very different temperature) compared to the present calculated redshift for the CMBR and observed temperature near 3K.
 
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Aug 31, 2021
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All the experts say that the universe IS expanding and the expansion is accelerating. They know because they've carefully measured galaxies from thousands of light years back in time to billions of light years back in time.
Why do they say "is" expanding when "was" seems more accurate.
I don't see any way they can tell what the universe is doing right now. What is the basis for saying the universe "is" doing anything?
"Was" belongs to the part of the Big Bang theory dealing with the past events: expansion after inflation, "is" belongs to the theory after the Hubble`s discovery of the galaxies red shift change. It is just the use of the words. You can not say in one term was and is. Wasis? How that does sound? Therefore, we say was or is actually meaning was/is in any case.
 
Aug 14, 2020
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Observed universe equals distorted universe. Observable equals distortional. It also equals a lot of potentially twisted premises and renderings. What is 'relative', and what is 'real', are not one and the same thing.
 

rod

Oct 22, 2019
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Folks, here is an example of 3D space expansion model interpretation using the BB model, something I look at when encountering discussions like this and questions. The farthest galaxy in the universe, https://phys.org/news/2020-12-farthest-galaxy-universe.html, December 2020. "A team of astronomers used the Keck I telescope to measure the distance to an ancient galaxy. They deduced the target galaxy GN-z11 is not only the oldest galaxy but also the most distant. It's so distant it defines the very boundary of the observable universe itself. The team hopes this study can shed light on a period of cosmological history when the universe was only a few hundred million years old..."From previous studies, the galaxy GN-z11 seems to be the farthest detectable galaxy from us, at 13.4 billion light years,.."

In the BB model, the redshift of 11.0 for the galaxy obtained is presented as the light time or look back time based upon Special Relativity and speed of light, thus 13.4 billion light years distance.. However the cosmology calculators show that 3D space continues to expand so the object has a comoving radial distance more than 32 billion light years distance today. According to Special Relativity, we cannot see that light today on Earth. The BB model has some components observable while other parts are not like comoving radial distances obtained using the math or the diameter of the universe today said to be some 93 billion light years across vs. when the CMBR first appeared, perhaps 80 to 82 million light years diameter. A complete list of all items not directly verifiable in the BB model is something I would enjoy seeing published :)
 
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The father of BBT, LeMaitre, initiated the theory because the redshifts, combined with GR (General Relativity), argued that the universe is expanding, not was (as if it’s not expanding now).

Then came more and more observations that matched the testable predictions from the theory.

In the 1990’s, evidence from supernovae measurements argue that the universe is accelerating in its expansion.
 
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We can never know what is really 'real', so it's useless to think about what is real.
"Useless to think about what is real." You just wrote, in your total dismissal of the real, that "relative" then becomes "real", thus they become one and the same thing since there is no other existence than relativity. I say again that they aren't the same thing.
 
Aug 14, 2020
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Folks, here is an example of 3D space expansion model interpretation using the BB model, something I look at when encountering discussions like this and questions. The farthest galaxy in the universe, https://phys.org/news/2020-12-farthest-galaxy-universe.html, December 2020. "A team of astronomers used the Keck I telescope to measure the distance to an ancient galaxy. They deduced the target galaxy GN-z11 is not only the oldest galaxy but also the most distant. It's so distant it defines the very boundary of the observable universe itself. The team hopes this study can shed light on a period of cosmological history when the universe was only a few hundred million years old..."From previous studies, the galaxy GN-z11 seems to be the farthest detectable galaxy from us, at 13.4 billion light years,.."

In the BB model, the redshift of 11.0 for the galaxy obtained is presented as the light time or look back time based upon Special Relativity and speed of light, thus 13.4 billion light years distance.. However the cosmology calculators show that 3D space continues to expand so the object has a comoving radial distance more than 32 billion light years distance today. According to Special Relativity, we cannot see that light today on Earth. The BB model has some components observable while other parts are not like comoving radial distances obtained using the math or the diameter of the universe today said to be some 93 billion light years across vs. when the CMBR first appeared, perhaps 80 to 82 million light years diameter. A complete list of all items not directly verifiable in the BB model is something I would enjoy seeing published :)
The universe (u) is a vast and fast vortex of movement really. The "fixed background observable universe" does not exist really. That observed fixed background universe is exactly the opposite of the reality.

The greatest movement in the universe appears to be in the foreground local closest to the observer. A fixed background universe is the biggest lie of the observable universe. The supremely greatest and therefore fastest (relatively speaking) movement is that very background universe. It has had the largest factors of time in which to move, to shift, the greatest distances, period, from all observably fixed picturing. It has exactly the same physics as QM's principle concerning particles' position and momentum. Knowing momentum in the observed background universe to be observed fixture, we can never know any background positioning or condition. The redshift does not mean accelerating separation in space. It means increasing and accelerating separation in relativity with all increasing distances in space and time from any observer. A dividing and multiplying parallelism. The greatest observable loss in relativity, the final most totaled loss to vortex, being at the horizon around 14 billion light years from any observer anywhere.

The observed fixed background universe in nothing but a mural formed of the accumulation and crunch of light in 2-d frames this way coming across the universe. The more a frame accumulates periphery to the center of the frames -- the serials of frames -- in transit, the more seized, the more fixed and fused, the more stilled and photo frozen, the more different from the foreground, the background picture in the frames. That background universe, relatively speaking, is a vortex, a boiling cauldron, of time warp movement in comparison to the foreground. But, once more, that is not what is observed.

"Is" is the real horizon. "Was" is the relative horizon.
 
Sep 5, 2021
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Thanks everyone, for a good learning experience. I'm so glad I found this forum.
After studying the responses and the links, I can only reach 1 conclusion: They should be saying "was." Saying "is" when referring to the expansion topic is misleading to anyone who doesn't have a high level of knowledge in the area of cosmology.
 

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