"There is no proof spacetime is infinite. It may actually not be."
Point taken. However, that does not change what appears to be the fact that spacetime is affected by all mass that has ever or will ever exist everywhere, and which seems to not be accounted for in extant calculations in the standard model. As I understand it only the mass that is observable by us instantly, whether at hand or removed at some distance that imposes a time delay due to light taking time to reach us, is accounted for. All the mass that exerts it's warping effect on spacetime is not reckoned, because only what we observe in the instant of observation is accounted.
What I propose is that mass we do not presently observe and have not accounted as warping spacetime does warp spacetime, and the proposal that there is some form of mass that only exerts gravitational warping, dark matter, is therefore unnecessary. That mass not observed at the instant of observation, whether what we observe is now present or has been present at the time in the past the speed of light reveals to us now, is the mass our reckoning of the warping of spacetime, gravitational lensing, indicates is not observed.
Proposing dark matter (and dark energy) is therefore unnecessary, and that dark matter proposed to account for the observed warping of spacetime is substituting for the mass that effects gravitational lensing we do not observe at the instant of observation but that certainly has and will exist and affect spacetime at the instant of observation.
I am very confuse, when you wrote this:
This is precisely a definition of dark matter, isn't it? I actually don't understand the difference.
PS: dark energy is different as this is the engine that allows the universe to expand in an accelerated way.
Dark matter as I understand it's description is proposed to comprise of WIMPs, weakly interacting massive particles, which have properties specifically that do not otherwise interact with other matter than gravitationally.
That is not ordinary matter at other times. That is additional and vastly different matter than ordinary matter at other times. Dark matter has properties that make it invisible, while ordinary matter at other times is simply not observable because we perceive time as an instant, and have not understood the nature of spacetime with which ordinary matter interacts.
What I discuss is that mass that existed yesterday, and all days before yesterday, is affecting spacetime today, and mass that will exist tomorrow, and all days after tomorrow, in addition to all mass that exists today, is affecting spacetime today. Ordinary matter that we observe today but are not observing at times past nor times to come is what is invisible and not accounted in the calculation of observed spacetime warping, gravitational lensing, we observe at the time of observation.
Mass affects spacetime. There is no place from which the affect of mass does not reach a given region of spacetime (except perhaps within the Schwarzchild Radius of a black hole), and this means there is no era in which mass has existed or will exist in which it does not affect a given era of spacetime, including the specific instant in which we are observing spacetime warping. The inverse square law governs the degree of affect mass has on spacetime, and reduces the amount of warping mass will effect the more distant mass is from the spacetime being warped, but there is no spacetime that is too distant from any given mass to be affected by it. Neither is there an era of spacetime that is unaffected by a given mass because that mass existed too long ago or will exist too far into the future from the instant in which the observation of spacetime warping is undertaken.
If mass observed at the time of observation is reckoned to warp spacetime in a given region of space, such as the surface of the Earth where the amount of warping produces 1G of acceleration, then what is actually happening is that all mass everywhere in the universe at all times in the past, all times in the future, and present, is exerting that spacetime warping we measure as 1G at that point and era in spacetime on the surface of the Earth where and when we take the measurement and calculate the spacetime warping.
Since the inverse square law reduces the affect of mass distant from the surface of the Earth to a negligible amount, generally such calculations consider only the mass of the Earth when calculating the warping of spacetime at some point on the surface of the Earth (in fact, as you pointed out, such local affects as mass has on spacetime are treated as a force using Newtonian mechanics, because that is far more easily calculable and accurate enough). However, these calculations ignore that it is the mass of the Earth yesterday, and all days prior to today, and tomorrow, and all days after tomorrow, in addition to the mass of the Earth today, that produces the given warping of spacetime observed at the time and place of observation and calculated to be 1G of acceleration.
Perhaps, if this description remains opaque, you can ask specific questions about the statements I have made to describe my understanding of what is happening when mass affects spacetime. It is simply that mass does not only affect space, but spacetime, and thus includes all times in which mass exists and not only the space in which mass exists, because mass exists in spacetime and not in space or time, neither of which exist.
Note: edited to improve clarity. I also note that mass may affect spacetime less or more the earlier or later from the time of observation, like mass further away affects a given region less. Also, the inverse square law may not be exactly how the affect of mass is reduced with increasing distance. I am incompetent to treat this understanding mathematically, and can only speculate that the specific rate of reduction of affect with increasing distance in space and time may be quite different than the inverse square law, being unable to make those calculations myself.
Sorry for the delayed answer, once again. Busy week, buy week… and this discussion is interesting. I cannot answer it in one line :)
WIMPs are only one possibility amongst many. Those are dark matter candidates particularly targeted at current experiments. But you have many many other options, ranging from very light particles to much heavier black holes. The only common ground is that they have gravitational effects. The rest belongs to the details of each model.
We can observe it through the byproducts of what this matter did in the past. For instance: cosmic rays. We just get them on Earth after a while. For that reason, when we observe the universe far far away, we in fact observe the universe as it was a while in the past.
From the rest of what you mentioned, there is actually one point on which I disagree. The arrow of time cannot be inverted. We can observe the present and the past (which corresponds to observing far away), but not the future. If I have well understood, it seems that you want to consider what is happening now, in the past and in the future. This is not possible. We can account for the first two in the calculations (including what is happening on the way and during history), but not for the latter. How would an event happening in the future impact us? This is what needs to be clarified, and this may be in contradictions with the known laws of physics.
Cheers!
I am happy to be patient to be availed your great understanding at your convenience to criticize my poor layman's understanding.
I, poorly read, am unfamiliar with other models of dark matter. However, any of them seem unnecessary given my understanding that spacetime, which includes all times including those we perceive as past and future times, is affected by mass such that it warps.
Regarding the arrow of time, I reckon that applies to our perception of it, rather than the actual nature of it, because time does not exist. Spacetime exists, and, as such, I see no possibility that it only exists in one 'direction', but rather is a unitary whole. We may not be able to perceive that whole, but that whole exists nonetheless, and we can observe that space is not unidirectional in any way, so there is, IMHO, essentially proof that time cannot, since spacetime is one thing.
It is not possible for us to perceive the future. However, we can conceive of it, at least estimate it. IMHO the future is an artifact of our means of perceiving, not the nature of reality. I conceive of reality as a gestalt, a crystalline clockwork that incorporates such beginning and end in it's whole.
I cannot understand how spacetime could exist otherwise. Would spacetime somehow erupt from probability in planckian quanta from the vacuum? How could the totality of the universe be inextant and only become extant per time, when time does not exist? It is our perception that is limited, not the universe, IMHO.
Thanks!
Please don’t worry. There are so many models available that is is hard to be up-to-date. I am definitely not myself fully up-to-date, although I know the big classes of models available (which is different from knowing all models taken individually).
The issue I have with the above statement is that it has problems with various known laws of physics. For instance, causality would be deeply broken and thermodynamics too. It is all connected to the arrow of time (see below). There is a one-way observed direction of time, at least at the macroscopic level. How would your understanding deal with this? This is unclear to me.
This is another thing that is unclear to me. Time exists, and the same manner as space exists. They are both components of spacetime. The fact that we can unify them in a more general concept does not mean the individual concepts are incorrect or cannot be taken individually to solve certain problems.
Finally, predicting the future is different from having the future impacting the present. This is where causality hits us. As said above, this is where I don't understand your reasoning and where I would need more clarifications.
Actually, you are not the only one who cannot understand this. This is a good question and hopefully we will see an answer, at least some day.
Have a nice week-end!