Thanks for sharing. This has been going around for a while now and its good to see that the odds of it being a statistical fluke are less likely which means there can be some more exciting new physics.
This is a good thing. Perhaps this can teach us some things about dark matter which we do not yet know or understand (like how much it interacts with normal matter).
I have no idea what you’re talking about. Can you elaborate? Are you talking about the flatness of the universe with regards to its geometry? That has nothing to do with infinity.
No, it has nothing to do with a multiverse. There are three main ways that our best theories lead to multiverses. One is with quantum mechanics and the many worlds interpretation. The next is with eternal inflation that leads to a cosmological multiverse. The third is the string theory landscape which could change physical constants in different parts of the the other multiverses.
The curvature doesn’t directly tell you anything about what is actually in the universe. It is just related to the ratio of the total density of stuff compared to something called the critical density. If you find that the density is close to the critical density (and thus the geometry is flat) then that means if you add up the density of all the stuff in the universe then it should be close to this value. So you add up the density of radiation and of baryonic matter and find that it is woefully short. If that’s all the universe contained then either there is a lot of missing baryons we are missing (which was a hypothesis since rejected thanks to the CMB and nucleosynthesis- I can explain more if you like) or there is more stuff in the universe or the universe is closed or open (one of the other geometries). Interestingly enough, there were some anomalies in galaxy clusters and in galaxy rotation curves that either could be solved by modified equations of gravity or another form of matter that is ‘dark.’ And then measurements of the ‘flatness’ of the universe have the curvature being flat to one part in a hundred or so with the error bars. So all of these pieces were coming together. There’s no reason why the universe had to be ‘flat,’ but yes it is particularly aesthetic
For me the word ‘fantasies’ sounds a little strange as there is nothing strange about other geometries. For example, the surface of the earth is not a flat geometry. When you travel in straight lines on the Earth you actually travel in a curve and two parallel straight lines can intersect and if you travel far enough you will end up back where you started! This type of universe in some sense would be a lot easier to visualize than a flat universe. I’m not sure what you are thinking though still, as the geometry of the universe is rather challenging to grasp. Wikipedia also has a summary of some of the things on the link you shared albeit updated with more accurate measurements:
The multiverse again is a separate question from the geometry of the universe.
To summerise, my point is, and this is very new, that the latest Hubble constant findings 'confirm an ever faster expanding universe, and put the previous modelling of Big Bang Theory in doubt - based on known physics.
Cosmologists are now seeking answers, looking at dark matter, dark energy etc (untestable, invible stuff).
Im adding to this quandary, but pointing out that all ‘evidence’ points to an infinite universe, as parrallell lines show zero curvature. (This seems to get overlooked, understated, and talked around). Another example here.
My thoghts are that theories of dark matter, dark energy etc, dont hold true against a zero curvature finding?
Even further, but still im trying to verify, distant galaxies are said to be of equal, or higher star brightness (Learner, Scarpa, 2014?). Big bang theory demands that they should be less bright, to my limited understanding/knowledge.
Perhaps the above evidence, at least puts doubt on the idea of a universal single big bang origin? Perhaps it opens up the idea of space as a blank canvas, where the birth of galaxies are not traceable to any plausible model?
I think, deep down, both the laws of physics, along with our own sense of importance, really struggle to face the ‘evidence’ of an infinite universe, similarly to facing our own mortality?
Kind of. About a year ago the discrepency was already published albeit less statistically significant. So it’s not ‘very new’ in that sense. As one author noted:
“This is not just two experiments disagreeing,” Riess explained. “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.”
They are mostly comparing the Hubble constant measured two independent ways and they don’t quite line up (and are less likely to be a statistical fluke now). The reason for this discrepancy is most likely new physics which is exciting! Since we don’t exactly know of a way to derive the Hubble constant besides just measure it, this means that we are one step closer to understanding the fundamental properties of our universe. Very exciting
Kind of. The stuff is not untestable as we have measured with great precision quantities of dark matter and dark energy. It doesn’t interact with lights so it is actually transparent instead of dark but that’s just its name. Specifically what is interesting is that this discrepancy with very accurate measurements of closer galaxies to further once could help teach us something about how dark matter actually interacts which is presently unknown except that it interacts similar to the weak force.
I guess. But it’s really not that interesting because of the limits of our ability to see back into the past. We are limited to see as much as 13.8 billion light years away but the universe is already bigger than that which as the article you shared says means we can’t exactly measure it for universes bound or unbound. By infinite all that that really means is that in a Euclidean plane the coordinates go from negative infinity to positive infinity. This would not be the case if the universe was closed as you can again think of the surface earth as what a closed geometry would look like. The coordinates of course would be finite in that universe. Better measurements though may yield some deviation from being perfectly flat but being perfectly flat is statistically consistent with the current standard deviation.
Dark matter and dark energy are completely consistent with a zero curvature universe. The flatness of the universe was one of the reasons why some cosmologists considered adding the cosmological constant (a particular type of dark energy) back into Einstein‘s equations of general relativity before we measured the accelerating expansion in the late 90s.
See for example:
This demonstrates All the stuff of the universe significantly changes its behavior over time. Specifically if the universe is flat that means that the sum of the two quantities there which represent the fractional energy density of dark energy plus the fractional energy density of matter must equal one. So basically the flatness of the universe is due to large amounts of dark energy and includes dark matter which has an impressive amount of evidence for it.
All the stuff of the universe significantly changes its behavior over time. Specifically if the universe is flat that means that the sum of the two quantities there which represent the fractional energy density of dark energy plus the fractional energy density of matter must equal one. So basically the flatness of the universe is due to large amounts of dark energy and includes dark matter which has an impressive amount of evidence for it.
I am not sure what you’re referring to, so I will have to look up the specific paper reference. I mean it’s possible that a supernova is quite bright as supernova can be much brighter than entire galaxy’s and distant supernova have been a large part of learning about distant regions of the universe.
It certainly would not do that. I wish that I could just teach a cosmology class right now in this thread, as there is a lot of observations that go into our understanding of the universe. While there are things that we do not yet know it certainly does not mean that the things we do understand and know are all wrong.
I studied physics at the University of Florida and Florida State University. I earned the credits for a minor in it, though my recorded major and minor are mathematics and economics.
The Standard Model (aka the Big Bang) appears to be based on an assumption that light behaves as sound does. Here is Edwin Hubble’s full statement on the subject, in the 1937 Royal Astronomical Society Monthly Notices:
“If the red shifts are a Doppler shift . . . the observations as they stand lead to the anomaly of a closed universe, curiously small and dense, and, it may be added, suspiciously young.
“On the other hand, if red shifts are not Doppler effects, these anomalies disappear and the region observed appears as a small, homogeneous, but insignificant portion of a universe extended indefinitely in both space and time.“
I understand sound is a longitudinal wave while light is a transverse wave. To my knowledge no one has provided empirical evidence that red shifts are a Doppler effect.