Maartenn100

But if you now travel close to a black hole for a few months and return to Earth, your perception of the elapsed time since the Big Bang will differ from that of other observers. Thus, your method of reckoning time violates the principle of relativity of time in my opinion.

Indeed: we measure with our clock. You say: 'Most clocks in galaxies run at about the same rate unless you're near a black hole or moving at a significant fraction of c'. The distinction between a universe where time, or age, is relative, and one where the universe's age can be precisely defined, is critical. Even minor discrepancies in time measurements suggest significant differences in our understanding of the universe: one with a definite age versus one without a measurable timescale.

I follow simple logical deduction from true premises: True premise: Space and time are no longer absolute as in the time of Newton. They are relative, since Einstein. Valid logical conclusion: There is no preferred reference frame for space. Supporting (thought) experiments: Observers can be conceived who measure a different space. (a photon, a hypothetical observer close to the speed of light approaching Proxima Centauri). Valid conclusion: Every observation of space is relative. THUS ALSO the observation of expanding space, as an interpretation of the observation of the Doppler effect of light emitted from distant galaxies, by 'expansion of space' moving away from us. True premises, logical reasoning, valid conclusion. And there is not only no preferred reference frame for space where every observation of space is relative, so also the observation of expanding space. There is also no preferred reference frame for time. Therefore, (elapsed) time since the so-called Big Bang is also relative. Different observers with their own clocks will measure a different duration since the Big Bang. So, the so-called age of the universe depends on which clock? Which preference do you give to which reference frame for (elapsed) time since the so-called Big Bang?

Your idea is to 'stick with the math'. The current models of the expanding universe, such as the Friedmann-Lemaître-Robertson-Walker (FLRW) metric, are, as I understand it, solutions to the Einstein field equations that describe the entire universe as a whole. These models assume the cosmological principle, which states that the universe is homogeneous and isotropic on a large scale. This is an unproven assumption that is simply taken for granted. One cannot oversee the entire cosmos and confirm this cosmologicle principle. Within this unproven framework, observations of the expansion of space are seen as consistent for all observers, despite the relativity of individual time and space measurements. New observations challenge the (unproven claim of) cosmological principle: Newly discovered cosmic megastructure challenges theories of the universe | Space | The Guardian So, the scientists do not 'stick with the math' either.

If there is simultaneity of all events in the block universe/spacetime, then there is no sequential order of events through time in the block universe. Then there is no timeduration in the block universe/spacetime. Then there is no time. Only observers measure timeduration. And they disagree.

The 4D spacetime can be conceptualized as a "block universe," an idea that stems from Einstein's theory of general relativity. In this model, the universe is viewed as a four-dimensional spatial structure, where time is akin to the spatial dimensions, and all moments in time—past, present, and future—exist simultaneously. It's this spatial Block universe that can only be conceptualised. In the block universe, the future is as 'fixed' as the past; both are already "written" and exist within the four-dimensional space. This concept is abstract and can be difficult to grasp since our everyday experience of time is sequential—we experience time as flowing from the past to the future. Visualizing the block universe as a geometric figuren, is an abstract concept in our minds. More real then the relativistic observations of time and space.

My point is that the universe without observers has no such properties like relative time and space distances.

4D-spacetime is very real. Even more 'real' then our relative measurements of space and time. You can not measure spacetime distances. You need to calculatie them. What you measure are relative spacedistances and time. Spacetimemetriek is calculated. Not observed.

But I start from the principle of relativity that since Einstein there is no absolute time and space anymore like according to the Newtonian worldview. Space is also relative. (and time) There is no preferred reference frame for space. So, the observation of 'space-expansion', seen from the point of view of an observer in a spaceship going at 0.99c of the speed of light towards Proxima Centauri, slowing down again, is 'the relativity of space' at work. This observer will see a so-called 'space-expansion' of the earlier contracted space/length in front of his spaceship, slowing down again. And this space-expansion is of the same kind of every other space-expansion we observe. If space is relative, everything we observe about space is relative and depending on observers. There are observers who 'see' zero space in the universe. Like a foton. So, if you say: 'space is expanding' (the universe is expanding), in my opinion: it's your particular ruler that is expanding, given your clock and given your position in spacetime. The metriek you use to calculate spacetimecoordinates is something conceptual. 4D-spacetime cannot be directly observed. The block universe is a conceptualised idea. More 'real' then our relativistic observations of space (and time), but a concept.

Thank you. But do you agree with the following statement: we can disagree on the measured distances (space) But we always agree on the calculated spacetimedistances. Spacetimedistances are calculated or deduced. Distances in space can be measured with lasers for example. The measured spaces are always relative, but the deduced (not observable) spacetimedistances are absoluut. So: every observed expansion of space is a relativistic observation of space. We cannot observe spacetime. (the universe in itself) We can only deduce it. Is that true?

I don't want to change the science of ART. I'm not capable of doing that! Only the interpretation to explain that science is different. The observed expansion is, for me, an observed expansion of our private ruler and not of the metric of the universe itself. Because when you want to know properties of the universe by itself, you have to look at an object that has the same properties for all observers: a photon in vacuum. Well, take that as a reference frame to posit things about the universe itself, without observers. You want to know something about space and time about the universe itself, independent of observers. Ask a photon in vacuum. A photon has absolute properties (not relative) for all observers. It can tell us something about the universe that is the same for all observers. The mathematics and science for it already exist. So, this is just a different interpretation of the existing scientific truths. Nothing changes about the science, but something changes about the interpretation of expanding space and what the universe without observers means by looking at a photon in vacuum. This is a matter of interpretation, not of science, because the science and math are the same: If you want to find something that all observers agree on, it's the properties of a photon in a vacuum. And as strange as it may sound: according to a photon, the actual age of the universe, and thus the real time in the universe, is ZERO. t' = (t - vx/c^2) / sqrt(1 - v^2/c^2) = 0 Time, just like space, is a property of observation. Not a property of the universe itself.

I will explain my idea and where it's coming from, even when it is wrong, so you understand the reasoning behind it: If we throw a ball in the air, and it falls down further away, it follows a bell curve in the air. According to GRT, it's a straight line in curved space. (and time). According to the ball's perspective, it's a straight line. But we, observers of space and time, we have a particular idea of a straight line, even in curved spacetime here. To us, the path of the ball is a bell curve, and our idea of straight uncuved and unstretched ruler is different from this bell curve of the ball, following it's trajectory through curved space. Well, it's this particular ruler of ours, this particular idea of a straight uncurved and unexpanded path, within a curved spacetime environment like the vicinity of Earth, the Sun, the Milkyway and clusters of galaxies that we see 'expanded', when we observe the redshift of the light of galaxies moving away from us, far way, according to Hubble's Law. Our particular idea of a straight line, as observers, is observed as stretched or expanded in spaces that are less curved then our space(time). That's a matter of perception. Even if the metric of the universe in itself is expanding, our particular idea of a straight line is observed as being stretched in less curved spaces than ours, because we have a particular idea of a straight ruler, an idea of a straight uncurved and unstretched ruler in our curved spacetime environment(s). Compare it with a clock. To us, time flows 'normal'. But in reality, time is dilated by the curvature of spacetime due to the mass of Earth, the mass of the Sun and the mass of the Milkeyway, the mass of the clusters of galaxies etc. But we 'observe' time normal. And it is this particular idea of time and this particular idea of a straight line in our curved spacetime environment that makes us see expanded straight lines somewhere else, as observers. So, in my opinion, this expansion of space, we observe, is a matter of perception or perspective from the point of view of an observer in a curved spacetime environment, watching objects in a less curved spacetime environment following a straight line. Even if the universe is expanding in itself. Personally, I believe that the universe in itself, without observers has properties of time and space that you can deduce based on an object that is absolute, like a photon in vacuum. For every observer it has the same values. So it can tell us something about the absolute (non-relative) nature of the universe in itself.

Do you know who examined the concept of the relativity of 'expansion', the reasoning behind their ideas, and why they were ultimately disproven? I'd like to understand why these ideas were considered incorrect. Thanks. Additionally, out of curiosity, I'm interested in learning more about the individual who first explored this idea and their rationale.

ok, thanks. Finally someone who explains this with patience without offending people. Thank you.

ok, thank you very much. I appreciate your effort. I don't know enough about these formula to understand it properly. My idea is wrong then.

yes, I agree with the expansion. Only, I think, it's a relativistic observation of space, not an expansion of the universe in itself. I think we should take a foton as a standard observer. It has absolute properties: for every observer a foton travels the same speed. A foton in vacuum can tell us something about the propereties of the universe in itself, without observers. It can give us absolute values (= not relative) about the universe in itself without having to avarage it out.

I agree. And that's why, in my opinion, you can not make absolute statements about the state of the universe in itself. Different observers will disagree on the expansion. Like James Web Telescope and ESA Planck Satelite disagree on the speed of expansion, even if they are both very accurate observers.

I have the following question: Imagine you are in a spaceship that is approaching the speed of light very closely. Normally, according to the theory of special relativity, you would see the space between you and the next planet you are traveling to shrink (length contraction). And then see it expand again as you decelerate. Suppose you are traveling very close to the speed of light towards a galaxy that is moving away from us due to the so-called expansion of the universe. What happens then to the space in between? Does it shrink or does it actually expand? Is the observer in the spaceship correct in saying that the universe is contracting in one direction (lengthcontraction due to high speed near the speed of light)? Or are we right from Earth, claiming that the entire space in the entire universe is expanding as a whole? You too easily ignore that the absoluteness of space expansion according to the Big Bang theory was refuted by the very precise measurements of the James Webb Telescope and the very precise measurements of the ESA satellite, which differed from each other. The only explanation is that different observers perceive this space expansion differently. Relativity of space-observations.

So, why are scientists still talking as if we live in an absolute universe with an absolute age (time) and an absolute amount of expanded space at any moment? So, why is this topic under 'speculations'? Or it is speculation or it is nothing new. It can't be both true.

But isn't it logical that when there is no universal clock, (no universal reference frame for time) there is also no universal reference frame for space? There is no universal ruler. And from that principle of relativity of space, can we logically infer that everything concerning space, absolutely everything, is also relative? Any theory that contradicts this must be flawed somewhere. That everything we see happening with space is a relativistic observation? (like the expansion of space far away (redshift of emitted light of distant galaxies.) There are referenceframes where the age of the universe is zero. And there is no prefered referenceframe for time in the universe. So, there are referenceframes where 'space' = zero too. And there are no preferred referenceframes for space in the universe. So, why scientists keep talking about an absolute universe with an absolute age and an absolute amount of expanded space at every moment?

Curvature versus Expansion: Both Relativistic Observations of Space We observe the deflection of light around massive objects. Light bends due to the curvature of spacetime around those masses according to the General Theory of Relativity (Einstein's General Relativity); From its own perspective, this photon follows the straightest path from A to B. From our perspective, spacetime there is curved, and the Light follows a curved path. To itself, there are no curved paths in time and space for objects over there. Just as the photon thinks of itself. From its own perspective, the paths are straight through time and space for every object within that spacetime sphere of that massive object. We, external observers, however, have a relatively faster ticking clock than the clock within that spacetime curved by those heavier masses for us. The spacetime there is curved, relative to our spacetime within our weaker gravitational field. So, when we see a gravitational field heavier than ours from here, we see a more curved spacetime there, relative to our less curved and, according to us, 'uncurved spacetime', which we take as a reference frame for curved spacetime: objects there follow a curved path, relative to our path. What happens then when we see a gravitational field lighter than ours from within our gravitational field? Then straight paths should become straighter than ours, but 'straighter than straight' is not possible. What is the reverse equivalent of following a curved path in a more curved spacetime? One will see space expanding between objects in a less curved spacetime than that of the observer. The expansion of space in the cosmos is the reverse equivalent of curvature. The reverse of a curved spacetime is an expanding spacetime when we observe a gravitational field weaker than ours. Both are relativistic observations of space.

In my opinion, there was not first the Big Bang and then an expansion of the universe. Now, the following viewpoint allows for the unification of spacetime or 'the block universe' of Einstein with the measurement problem in quantum physics. I believe there was first a 4D block universe where everything is simultaneously 'accessible,' a metaphysical 4D spacetime. Why metaphysical? Because as living beings, we are only capable of perceiving a 3D universe through time. Einstein already said: "time is an illusion of our consciousness." We experience the unfolding of events through time, sequentially. But that is not how the larger reality itself is. All events from the past, present, and possibly future are accessible at the same time when we have access to the block universe. To 'observe' this reality, you need to be in a different state of consciousness. Having a unitive experience, as the mystics say, lets you consider this Ultimate Reality. And here, a role is designated for our consciousness. Through our consciousness, we have access to 'time' in a 3D world where we experience events sequentially, and closing our eyes, dreaming, and ultimately 'dying' then means gradually gaining access to the 4D reality, which mystics and psychonauts sometimes have access to. The Minkowski spacetime or the block universe. Where all information from the past, present, and future is accessible. The spacetime, or the Minkowski metric, is a deduced reality where everything exists simultaneously, in past, present, and possibly future. A 4D reality that we can access when we are in a different state of consciousness."

Space and time observations are inherently relativistic observations, relative to our clock and ruler that we use as a standard. (Einstein) Therefore, as observers, we are always in the center of an expanding universe, expanding in all directions in space. This is because, both in terms of time and our spatial measurements, we are the standard for what we observe as 'curvature' and 'expansion' (frame of reference).

Well, we always see through the lens of a clock when we observe space. And whenever space is observed as curved or expanded, there is a difference over there with our clock. Due to (gravitational) time-dilation or time contraction. We cannot see not through the lens of our clock or ruler when we observe space. (and time) Because, to us, our clock ticks 'normal', where ever we are, our ruler and our clock are locally uncurved and unexpanded. (to us). We take our clock and our ruler as flat, as a reference (frame) for observed space somewhere else. But, wherever we are, we see everything further away from us expanding in all directions. Because to every observer, his local clock and ruler are taken as the Standard/reference for time and space measurements elsewhere.

The James Webb Telescope confirms the measurements of the Hubble Telescope regarding the speed of the so-called expansion of the universe, thereby ruling out presumed errors of the Hubble Telescope. This is problematic because the ESA Planck satellite, through another, also very accurate, measurement method, came to different conclusions. (see here for more information) Personally, therefore, like an increasing number of scientists, I think there is something fundamentally wrong with the Big Bang theory and the idea of an objective expansion of the universe. As I have previously indicated on this forum, I believe that if gravitation in the theory of general relativity is equivalent to acceleration in the theory of special relativity, then observed space expansion or observed space contraction in special relativity also has its equivalent in observations of space (from a time frame with a specific clock) in gravitational fields. Different observers will therefore disagree on the degree of space expansion. The universe itself is not expanding; it is our relativistic observation of space that differs, for different observers who take their clock, their own time, as the standard for observations out in space. It is a property of space observation that the observed space can shrink or expand, depending on the different clocks in the gravitational field that we, as observers, have as a standard. Hence the difference in measurements between ESA's Planck satellite on one hand, and the Hubble and James Webb Telescope on the other.