Hubble tension is now in our cosmic backyard, sending cosmology into crisis

[Classical Motion]

Pardon me Gib. Didn’t mean to be insulting. Or superior. I have a radio experiment to show you those slices. One slice at a time.



Maybe.

 

[Gibsense]

Pardon me Gib. Didn’t mean to be insulting. Or superior. I have a radio experiment to show you those slices. One slice at a time.



Maybe.

Hi, I am unlikely to be able to understand the radio experiment but I can give it a go. Maybe others would appreciate an insight. Perhaps a different thread - or maybe you have already done this. If you can prove your point it would be wicked.

 

[Gibsense]

Just to examine the difference between CMB data and standard candles in an attempt to suggest a reason for Hubble Tension:

• The light we receive as the original 'flash' from when the universe becomes transparent (due to expansion/cooling) has been around almost forever. It would be reasonable to suppose that the 'Big Bang' origin was at coordinates of 0,0,0,0,0, ... that is at one specific place (very nearly) in a multidimensional origin.
• If the universe had a singularity origin it is reasonable to assume the expansion occurred spherically
• Given the above the CMB light may have travelled several circuits of the universe. It has 'stretched' directly (solely) due to space stretching.

The light from Standard Candles is perhaps different as:

• If the universe is spherical then space curvature will result in light observed with effects similar to light emerging from the curvature of gravity wells. That is the light will be dilated.
• It is restricted to the observable universe and has no origin within spacetime.
• The apparent t=0 location is at 90 degrees (as a radius to us in a spherical universe embedded in at least 4 dimensions). This is not the location of a BB but is the point at which the rotation of 3d space due to curvature ( an effect similar to a body entering the event horizon of a black hole seems to dim to zero)

That the two results for the Hubble Constant are so close would perhaps indicate that the Observed Universe is nearly equivalent to the actual Universe (a similar result to that that Myers has conjured).

The Hubble Tension is about understanding why different methods of measuring the universe's expansion rate give slightly different results. CMB data and standard candles aim to measure this, but they do so differently. The CMB comes from the early universe and has been stretched over time due to the expansion of space itself, while light from standard candles is more about the here-and-now universe. If the universe has a spherical geometry, space curvature could change how we perceive distances and expansion rates.

 

[AtreidesoftheThames]

Measurements of the distance to the Coma Cluster of galaxies find that it is millions of light years closer than the standard model predicts.

Hubble tension is now in our cosmic backyard, sending cosmology into crisis : Read more

First of all, I don't know why these observations are being framed as a crisis, to me it would be something to be celebrated, because we are becoming more aware of our own ignorance and therefore are able to deepen our understanding of the universe around us. I think it's important to always keep in mind that on the Kardashev scale we are still a type 0 civilization, which means that everything that we think we know, is incomplete at best and completely misguided at worst. Throughout history we have assumed many times over that we understand the nature of something or other, something fundamental about the nature of reality, only to be proven wrong eventually as new ideas have come forth. Galileo is a good example of this although there are many others. I remember coming across a book titled "The End of Science?" or something like that and the sheer hubris of it was just insulting to me on a personal level, I couldn't even bear to look at it more than that but this kind of thinking is really more like "The Death of Science" imo.

But this particular problem is really interesting, and I think it has something to do with the nature of spacetime itself. Now I'm just a layman but has anyone considered that the problem lies with time itself? I mean to say that since time is fluid perhaps it has somehow affected key measurements in areas of intense gravitational distortion between where we are and what we are trying to measure? Again I'm just a layman so any thoughts/enlightenment would be appreciated, thank you.

 

[Gibsense]

But this particular problem is really interesting, and I think it has something to do with the nature of spacetime itself. Now I'm just a layman but has anyone considered that the problem lies with time itself? I mean to say that since time is fluid perhaps it has somehow affected key measurements in areas of intense gravitational distortion between where we are and what we are trying to measure? Again I'm just a layman so any thoughts/enlightenment would be appreciated, thank yo

I agree that understanding "What is time?" can be enlightening. Most of my posts here stem from my thoughts on the nature of time. I'll share some ideas that might be useful and try to avoid boredom.

Spacetime, to clarify, is a concept similar to the idea of volume where three separate dimensions come together but for Spacetime four dimensions are unified in a single concept. All four dimensions are orientated at 90 degrees to each other. As some prefer to say, they are 'orthogonal'. Time therefore is orthogonal to volume (3D space).

This simple fact shows that the shape of spacetime is crucial to determining the direction of time. If the 3D space in which we exist is any shape other than infinite Euclidian (without gravity wells) then time cannot be a parallel 'arrow'. In my view, this arrow insistence is a crutch to avoid more difficult concept visualisation. Mathematically we can consider the daft idea that the solar system revolves around the Earth as a centre - it is possible and logical. Similarly, the 'arrow' get out can be supported mathematically and I expect it avoids further debate of 'strange' concepts.

The process of time must occur in different directions within an embedding space. It is consistent to express relativity using geometrical terms; for example to express dilation in terms of rotation of 3D space (Taylor & Wheeler). There are fundamental consequences of this view of the nature of time

I would like to quote an independent opinion of my comments as I think it adds some support and is helpful to an understanding:

"The concept of spacetime as a unified four-dimensional entity, with time being orthogonal to the three spatial dimensions, is a fundamental aspect of modern physics.

That the shape of spacetime may determine the direction of time is interesting. In general relativity, the curvature of spacetime is determined by the distribution of mass and energy. The curvature does affect the passage of time. Time dilation occurs in strong gravitational fields, and time appears to pass more slowly as compared to regions with weaker gravitational fields.

The notion that time cannot be a parallel 'arrow' in a non-Euclidean, curved spacetime challenges the traditional view of time as a linear progression and suggests that the geometry of spacetime plays a crucial role in how we perceive and experience time."

AND I should add this description of General Relativity which may help via the links to Wikipedia:
" General relativity generalizes special relativity and refines Newton's law of universal gravitation, providing a unified description of gravity as a geometric property of space and time, or four-dimensional spacetime. In particular, the curvature of spacetime is directly related to the energy and momentum of whatever present matter and radiation."

 

[m4n8tpr8b]

How can we know that the CMB is a 'direct' measurement when there is nothing to verify the accurate impact of the mass of the Universe on its 'evolution'? Isn't red shift of the CMB essential to its de-convolution and thereby its interpretation? It seems possible that 'direct' is not so direct (to say nothing about its de-convolution).

The other commenter was wrong, using CMB is not a "direct" measurement, either, there is no such thing. It is a comparison of the scale of structures observed in the sky by telescopes at different cosmological redshifts with those in the CMB. Structures as in what we see in the sky, perpendicular to the viewing direction; structures at a given redshift. All of these concern electromagnetic radiation that travelled the same time to us, so this isn't impacted by the travel of the photons.

What de-convolution filters out is not cosmological redshift but redshift and blueshift due to the motion of the observer relative to the CMB - the motion of a space telescope around Earth + Earth's around the Sun + Sun's around the center of the Milky Way Galaxy + the motion of our galaxy in the Local Cluster + the motion of the Local Cluster towards the Great Attractor.

So based on this, galaxies forming superclusters must be converging because the space between them is decreasing. The galaxies forming a given cluster then would be blueshifted when looking at one from another?

But I have read that most galaxies are redshifted relative to others, due to the expansion of space, even in superclusters.

If galaxies approach each other, that's not cosmological contraction, that's motion within (expanding) space as influenced by gravity (a motion faster than the cosmological expansion over the scale of distances within a cluster).

The only way to measure relative redshift between other objects is if one galaxy is seen in front of another and we see absorption lines from interstellar matter in the closer galaxy in the spectrum of the emission of a bright object of the more distant galaxy. But normally, we can only measure redshift relative to Earth, and can only guess how much of it is cosmological redshift and how much is motion relative to the local "rest frame". In clusters, differences in redshift are a good indication of motion around the cluster centre of mass.

 

[m4n8tpr8b]

I agree that understanding "What is time?" can be enlightening. Most of my posts here stem from my thoughts on the nature of time. I'll share some ideas that might be useful and try to avoid boredom.

Spacetime, to clarify, is a concept similar to the idea of volume where three separate dimensions come together but for Spacetime four dimensions are unified in a single concept. All four dimensions are orientated at 90 degrees to each other. As some prefer to say, they are 'orthogonal'. Time therefore is orthogonal to volume (3D space).

This simple fact shows that the shape of spacetime is crucial to determining the direction of time. If the 3D space in which we exist is any shape other than infinite Euclidian (without gravity wells) then time cannot be a parallel 'arrow'.

You start from a good foundation but go off in some bad direction. You correctly say that time is a fourth dimension orthogonal to the three space dimensions, but then say something about "parallel", and bring in direction ("arrow"), that is the progression of time, which goes beyond even general relativity. I'll try to put some order in there, though it's difficult to explain to laymen.

Time being orthogonal to the three space dimensions is not what makes spacetime; that's something you already have in Newtonian physics. What Einstein changed, already with special relativity, was to show that (1) time is somehow different from the space dimensions, (2) if you consider what different observers see, all four are inextricably linked. Linked how? What the general public usually hears about is time dilatation (clocks running slower for someone passing you by at speed), but a more mind-blowing and fundamental way to describe it is through what happens to the concept of "a moment in time".

We experience time as a progression (along the time dimension) and think of it as something the entire universe goes through as a whole. You could say that a "moment in time" is a 3D slice of the 4D Universe which contains all the events that happened to different objects at the same time. However, Einstein showed with special relativity that our everyday concept is wrong: the events that form a "moment in time" for one observer are different from those for another observer.

Say you sit on top a mountain in the middle of a mountain chain, and observe three lightning strikes into your mountain and both of its neighbours, and determine that they all happened at the same time. If just when the lightning hit your mountain, an alien races past you and along the mountain chain on a flying saucer, you would think that she will also observe the three lightning strikes to have occurred at the same time, but this isn't the case: he would determine that the lighting at the mountain she is flying towards happened before the one at your mountain, and the one at the mountain he was flying away from happened later.

(Without going into details, the reason such mind-bending spacetime geometry had to be introduced was to explain some mind-bending observations, specifically the fact that the speed of light in vacuum is exactly the same for every observer, independently of their relative speed. And one consequence of this mind-bending spacetime geometry is the famous equation for the equivalence of energy and mass, E = mc^2.)

So spacetime is a tapestry spanning all past and future events across the Universe, for which you have to adopt a notion of timeless "existence"; what slice of spacetime forms a "moment in time" depends on the observer, and the passage of time is a very subjective sensation any observer experiences at any point on its timeline across spacetime.

Now, while special relativity (which links space and time into spacetime) is very good at describing how objects move through space, and general relativity (which accounts for the bending of spacetime, where the ratio of the circumference and diameter of a circle can be both less and more than pi) is very good at describing the effect of gravity at both astronomical and cosmological levels, neither of them explain the subjective sensation of the passage of time. Nor can they give a fundament to the only theory of physics directly connecting this passage of time to an objective macro level: the Second Law of Thermodynamics (entropy increases). This remains to be solved, it's just that physicists talk about it less than about quantum gravity.

The only "parallel" thing I can think of with relation to time & cosmology is the multiverse hypothesis, where multiple 4D spacetimes exist, either along some extra dimensions or as quantum superpositions. If, specifically, you want to invoke the multiverse to explain quantum mechanics by assuming that the Universe splits in two due to every observation, you again run into problems with the non-local concept of moment in time.

 

[m4n8tpr8b]

• The light we receive as the original 'flash' from when the universe becomes transparent (due to expansion/cooling) has been around almost forever. It would be reasonable to suppose that the 'Big Bang' origin was at coordinates of 0,0,0,0,0, ... that is at one specific place (very nearly) in a multidimensional origin.
• If the universe had a singularity origin it is reasonable to assume the expansion occurred spherically
• Given the above the CMB light may have travelled several circuits of the universe. It has 'stretched' directly (solely) due to space stretching.

Nope. You still think of space as some independent ethereal background (within which the Big Bang was an explosion), instead of something we are embedded in which expands itself. The Big Bang "happened" "everywhere", in the entire observable universe, in fact well beyond (we see ripples in the CMB which must have been generated well before the release of the CMB, and suggest a Universe that extends beyond and had a roughly uniform structure well beyond the observable universe. The Big Bang singularity means that, if we use all the physics we know to extrapolate our expanding Universe backwards from what we can observe, we get to a point in time where all distances become zero. (Of course, our physics is finite, not applicable to what happened before the entire observable universe was contained within the volume of a present-day atom, so whether there was really a singularity or something even stranger, we can't tell.)

 

[whoknows]

Nope. You still think of space as some independent ethereal background (within which the Big Bang was an explosion), instead of something we are embedded in which expands itself. The Big Bang "happened" "everywhere", in the entire observable universe, in fact well beyond (we see ripples in the CMB which must have been generated well before the release of the CMB, and suggest a Universe that extends beyond and had a roughly uniform structure well beyond the observable universe. The Big Bang singularity means that, if we use all the physics we know to extrapolate our expanding Universe backwards from what we can observe, we get to a point in time where all distances become zero. (Of course, our physics is finite, not applicable to what happened before the entire observable universe was contained within the volume of a present-day atom, so whether there was really a singularity or something even stranger, we can't tell.)

Likewise what if you extrapolate forwards? How do Planck units and absolute zero feature?
(layman question)

 

[m4n8tpr8b]

Likewise what if you extrapolate forwards? How do Planck units and absolute zero feature?
(layman question)

Currently, the extrapolation forwards is accelerating expansion forever, but the exact details depend on factors we don't know enough about, above all the properties of dark energy. There is a theoretical possibility of a Big Rip, a singularity that is the opposite of the Big Bang one (all distances become infinite), but of course our physics breaks down before that; and current observations indicate dark energy is not of the kind to cause a Big Rip.

Due to the accelerating expansion, eventually, the limit of the observable Universe would not be from where the cosmic microwave reaches us, but closer, because far-away galaxies would be redshifted beyond detectability. In a trillion years, we would only see the Local Supercluster, and later just our own galaxy (which would then be the merger of all galaxies in our Local Cluster), assuming we will have distant successors and they'll live around a star that is not ejected. It will still take a long time after that for the last dwarf stars to burn out. Then, after an incredibly long time, all stellar remains would end up either in black holes or as free particles, and after another incredibly long time, all black holes would evaporate. Then in the subsequent hyper-cool Universe (approaching absolute zero), a quantum fluctuation might start new Big Bangs. But this is again beyond current science.

Planck units are relevant to quantum gravity, the current holy grail of theoretical physics, which would be the application of quantum theory to gravity. If quantum theory can be applied to gravity, then quantum effects would show at the scale of Planck units. For cosmology, this means that our understanding of the Universe breaks down where some conditions approach Planck units. As I wrote, if we extrapolate backwards, we get to a singularity where all distances become zero, but our understanding really applies back to one Planck time short of that, which is 5*10^-44 s, that is zero - dot - 43 zeroes - 5 seconds.

 

[Gibsense]

Nope. You still think of space as some independent ethereal background (within which the Big Bang was an explosion), instead of something we are embedded in which expands itself. The Big Bang "happened" "everywhere", in the entire observable universe, in fact well beyond (we see ripples in the CMB which must have been generated well before the release of the CMB, and suggest a Universe that extends beyond and had a roughly uniform structure well beyond the observable universe. The Big Bang singularity means that, if we use all the physics we know to extrapolate our expanding Universe backwards from what we can observe, we get to a point in time where all distances become zero. (Of course, our physics is finite, not applicable to what happened before the entire observable universe was contained within the volume of a present-day atom, so whether there was really a singularity or something even stranger, we can't tell.)

I know it is easy to get into a teaching babytalk stance so I am not too upset .

Nothing you have said in the post highlighted above varies from standard understanding but if the universe is not Euclidian flat you miss out on a deeper view of what is real.

The idea that the Big Bang is everywhere is standard response stuff and true for 3D thinking. However, if we acknowledge the reality of 4D embedding space the description you extoll becomes trivial.

In a 4D context, the Big Bang is considered the origin of an expanding n-sphere, distinct from the expanding 3D universe. This separation is defined by the radius of time. A straightforward calculation demonstrates that the expansion rate of 3D space aligns with this radius of time. Therefore the Big Bang is not everywhere. But its effects are.

Relativity (to answer your previous post) is a geometric theory where the mathematics used in a spacetime context actually works. However other ways of expressing relativity also work and match your 'spacetime' convention. I will be happy to elucidate further if you wish.

 

[Gibsense]

You start from a good foundation but go off in some bad direction. You correctly say that time is a fourth dimension orthogonal to the three space dimensions, but then say something about "parallel", and bring in direction ("arrow"), that is the progression of time, which goes beyond even general relativity. I'll try to put some order in there, though it's difficult to explain to laymen.

Read it again. Current Astronomy (and presumably you) treats time as an arrow heading in one spatial direction where different locations have time running parallel.

This is clearly incorrect. The geometric theory of Relativity has, for example, shaped space. And time runs orthogonal to that shape. Not parallel! Duh! Hence dilation but expressed as a rotation in 4 Dimensions. It does not go beyond General Relativity, it is incorporated - just expressed differently.

Another rather obvious point. If the direction of time varies it is not a 'time dimension' or rather time is not a dimension. Time can progress in any direction available to 4D embedding space

 

[Gibsense]

We experience time as a progression (along the time dimension) and think of it as something the entire universe goes through as a whole. You could say that a "moment in time" is a 3D slice of the 4D Universe which contains all the events that happened to different objects at the same time. However, Einstein showed with special relativity that our everyday concept is wrong: the events that form a "moment in time" for one observer are different from those for another observer.

This comment is a bit vague and misleading. The time as applied by cosmic time is the same for everything (if we were to assume a smooth surface - in 4D - instead of the actual rough surface which causes small variation - the hills and valleys shown in the structure provided by the arrangement of galaxies for example). Clearly from observation, time is different depending on many factors as expressed by relativity.

 

[Gibsense]

We experience time as a progression (along the time dimension) and think of it as something the entire universe goes through as a whole

Nope. This is old hat 'arrow of time' thinking incorporating parallel (whole universe)

Think: some parts of the universe may expand slightly faster (areas of low mass) or better put 'be ahead' Time is not a single dimension - it acts orthogonally.
None of what I assert will make sense unless you assume a space of multiple dimensions and escape Flatlander thinking

 

[Gibsense]

Time being orthogonal to the three space dimensions is not what makes spacetime; that's something you already have in Newtonian physics. What Einstein changed, already with special relativity, was to show that (1) time is somehow different from the space dimensions, (2) if you consider what different observers see, all four are inextricably linked. Linked how? What the general public usually hears about is time dilatation (clocks running slower for someone passing you by at speed), but a more mind-blowing and fundamental way to describe it is through what happens to the concept of "a moment in time".

Moments in time are akin to n-spheres of increasing diameter (shells if you like or onion rings) if you are thinking of the universe as a whole. Otherwise all sorts of factors need to be considered in order to agree 7.5pm on the 4th Feb 3030 and the method employed is called relativity spacetime.

 

[m4n8tpr8b]

Moments in time are akin to n-spheres of increasing diameter (shells if you like or onion rings) if you are thinking of the universe as a whole. Otherwise all sorts of factors need to be considered in order to agree 7.5pm on the 4th Feb 3030 and the method employed is called relativity spacetime.

You clearly did not understand anything I wrote, in spite of what you call "teaching babytalk", and it appears you have no idea what you're talking about. You use several words outside of their meaning, yet you make very confident proclamations, putting your "understanding" above all actual scientists who studied this stuff for years and know the meaning of all the words you misuse. The stuff I wrote can be understood at a layman level, but it needs some humility first.

 

[typodrive]

Based on my interpretation of physicist Subhajit Waugh’s theory, “Unified Physics and Cosmology: the Theory of Everything”, the three dimensional universe we seem to occupy was spawned by a four dimensional big bang with our resulting 4D hyperballoon structure expanding at the constant speed of light.
From this, and with apologies to Mr. Waugh, my interpretation is that as our hyperballoon structure expands, it’s two layered fourth dimensional thickness becomes thinner with time.
After about 13.6 billion years since the big bang this 4D thickness is now about 1.616255×10−35 meters, which is the Planck length. This is why our universe seems three dimensional and from our 3D perspective this is where the fourth spatial dimension has gone. It is what we perceive as the quantum realm.
Back to the red shift question, this all implies that the Planck “constant”, h is actually a variable and it becomes smaller as our universe continues to expand at the constant speed of light.
Therefore from the equation

F=E/h
As we go back in time, h would be a larger value and all celestial bodies would emit light at higher wavelengths than those today. Their light would be redder and that would explain the redshift phenomena.