The Dark Energy Delusion | Claudia de Rham Public Lecture 

Claudia has an amazing gift for making me think I understand what she is saying.

It's a great satisfaction for a common man like me, to be able to understand the whole presentation, from a scientist of her level. Thanks professor De Rham and Perimeter Institute. 💐

Always appreciate that the Perimeter Institute shares these lectures and thankful that all 3 levels of government in Canada support their research, thank you

How wonderful, I have never even considered the possibility that Gravity had a finite range. But now after prácticing physics for 50 years, I can not unconsider the possibility. The more we know, the more we discover how much we did not (or do not) know

Professor De Rham is certainly a great teacher, she made such complicated subject approachable by laymen.

I had the pleasure of attending this lecture in person. Also, I am a CBC junkie so appreciated the interview with Nahlah Ayed (CBC: Ideas and Ideas in the Afternoon)

The theory being proposed here sounds like a sub-type of Modified Newtonian Dynamics (MOND) whereby the argument is that gravity operates differently at different length scales. From what I can tell, most physicists don't put any credence into this theory because it creates more problems in an attempt to solve only one problem (gravity) and isn't supported by the corroborating evidence (CMB power spectrum, etc.). She is basically arguing that the graviton (which likely exists but has yet to be discovered) should not be massless (she compared it to the weak force bosons W+/- & Z and the Higgs scalar boson). Massless particles must travel at the speed of light; particles with mass cannot. Massless bosons have inifinite range (i.e. photon); massive bosons have finite range. Her proposed theory is controversial to say the least. Gravitational waves as predicted by Einstein's field equations travel at the speed of light. The advanced LIGO observatories have documented numerous events by now; one would think that news of the signals traveling slower than the speed of light would have made world headlines. Granted that LIGO is not sensitive to most frequencies of gravitational waves. Recently there was also a massive and impressive paper on using a Pulsar Timing Array (PTA) to study gravitational waves of all frequencies; nothing from that study that I recall mentioned anything about those waves traveling slower than the speed of light. She is correct in stating that the future planned LISA experiment would be more sensitive and would provide an important rule out, though the PTA study essentially used a naturally occurring apparatus that is far larger in size than anything LISA could achieve. It truly would be surprising if LISA's future data didn't align with LIGO and PTAs. I should also mention, that most physicists (from my understanding) believe that the vacuum energy is the leading candidate for what dark energy most likely is. *Note: this impression is just based on this public talk; I have not read her published work(s) on this.

The gravity of listening to Claudia de Rham is such that one cannot resist her pull. I’m very grateful to be able to watch her in action.

4:32 RIP that mans phone (in the lower right corner)

Whenever I think about gravity it brings me down

I have some background in this field. As a result, I can appreciate this superb presentation. I disagree with some elements of it but, on the other hand, she has managed to provide chapters in a general picture that I found lacking in most other presentations. My appreciation of this presentation becomes borne out when I watch it again. Watching this was a rewarding time investment. Thank you.

Thank you! I'm an undergraduate in physics, and I've been struggling to decide which field I'll pursue in my masters. This video gave me a lot to think about

Awesome! This is the kind of 'outside-the-box' thinking we need more of in theoretical physics. Thank you!!!

incredibly fascinating she's plumbing the depths of how far gravity can actually reach, because it clearly has such a profound effect on the estimate for the expansion rate of the universe. Learning how to harness the energy of the Higgs Field clearly is the task of our generation

This is how I understand gravity, any cosmologists or quantum physicists out there feel free to correct me: space-time is fluctuating with the quantum vacuum energy or Higgs field, which interacts with mass via the Higgs Boson. All energy and matter is just different ripples and twists and distortions of space-time, starting with photons, quarks and gluons, going up to electrons and protons and all the other particles. Put more mass or energy into an area of space-time and all the ripples and twists from that mass stretches the space-time more. It's like poking the middle of a piece of spandex held in a taut frame, except it's in 3D. This distortion of space-time and the interaction of Higgs Bosons with mass is what we call gravity, or inertia (same thing). The quantum vacuum interactions are sort of "tugging" on the mass as it tries to move through space-time; the more mass or more dense the object, the more it tugs so it's harder to accelerate or decelerate. The space-time distortion causes objects to appear to be attracted to each other, without the distortion we would be thrown off the Earth's surface and the Earth would leave the Solar system and go in a straight line. The faster you travel through the vacuum energy, the more energy it requires to accelerate, because you are interacting with more vacuum fluctuations the faster you go, hence the limit of the speed of light. For the person travelling near the speed of light, time seems to pass slower than for people who are stationary (special relativity). Near to a large mass like a black hole, time passes more slowly compared to being at a galactic void (general relativity). Where space-time is stretched or where you are moving very quickly there's less time passing. At the same time as all that is going on, space-time is also expanding, so that piece of stretched spandex is growing from every point in space. This causes light to red-shift because the wavelength has stretched from blue (short wavelength) to red (longer wavelength). It also means galaxies are generally getting further away from each other, so one day we won't be able to see them anymore. Extremely large galaxies seem to be held together too well, and rotate too quickly on the outer edges. They should fall apart based on our current physics, and based on the amount of mass observed, but they don't. This led to a band-aid being applied called dark matter, which adds the missing mass back in, and we just say it's invisible. To explain the expansion, we made another band-aid called dark energy. These band-aids are a source of contention because there's so far not much evidence they exist, and it's probably more likely that our physics is wrong (The Crisis in Cosmology).

If it's recognized that "empty" space is filled with something, the Higgs Field, then we can no longer make fun of the idea of a universal aether. In fact, it could be that very aether that limits the speed of light, preventing it from being instantaneous, which is a very good thing.

Well Presented. Clear Presentation of "What We Don't Know". AS A TECHNOLOGIST , several of us often wondered TWO THINGS, 2 QUESTIONS: 1.) If we captured a Cub Meter of Pure Space - Do We Really Know What Is Inside It? 2.] How do we know that the Universe isn't Expanding Within- HOWEVER it is being "PULLED" By Forces Outside The Universe even other Universes?

What we call gravity is the tip of the ice burg. It's the "visible light" of the whole EM spectrum in that it's a piece of a larger more fundamental phenomenon. That phenomenon is temporal relativity. Under certain conditions temporal relativity gives rise to this attractive force between masses we call gravity, however under most other conditions temporal relativity leads to repellent forces. The key is understanding that in spacetime, any dimension has the capacity to be temporal, and more importantly, that there is absolutely no requirement for any two observers to agree on what dimension is temporal. So I think she's really close, but it's not that gravity has limits, it's that eventually in the vast void between masses the temporal directions between the void and the large bodies of mass are no longer aligned enough to remain attractive but instead become repellent. With all the insight that Einstein brought to the table with relativity, our community is still so steadfast in its assumption that the direction of time itself is somehow uniform. I really do think the key insight is the realization that the direction of time is itself relative.

All you smart people in the video and in the comments give me such a burst of joy. Keep thinking😎

What would be interesting would be to find out what was the big impedement was that prevented the audience member from silencing their phone once it started to produce it's msg-receivied jingle. No matter the lecture or performance, there is always at least one audience member who find it difficult to comply with the silent mobile phone request. Good on Claudua for not being distracted by the noise and staying on point.

What an incredibly clear challenge to conventional thinking by an absolutely brilliant theoretical physicist !

I feel like dark matter is the leftover stretch of the fabric of space-time, that's wicking matter along itself like water up a papertowel. Heat death is the ultimate distribution of all things along the fabric. The universe will "dry out." Gravity could've been the 1st force, so concentrated that it forced the other forced together. All the forces are working against the wicking effect. Whatever it takes for matter to stay together and not dissipate.

how admirable is her grasp of the English language... Thats all i got from this video. It must be the theoretical physicists are reading much more non-physics books than the non theoretical physicists :) One may even dare to say that they read English literature...

Another way to think of curvature is as a gradient. Think of time as causal energy. Think of mass as "feeding" on causal energy. The space surrounding a mass boundary would have a lower causal energy than the said mass. According to the law of Entropy, high energy states move towards low energy states. Gravity is a causal energy gradient surrounding mass, not a literal curvature of Space. Mass (high causal energy) falls towards the low causal energy. Massive bodies aren't attracted to each other, they're moving towards the causal deficit that each creates in the surrounding space. Clocks tick faster as they get farther away from a massive body because of the increase in available causal energy.

Einstein’s work is only about 120 years old now, it’s good to see people are open to think beyond it as we enter the first quarter of the 21st century.

Great lecture. I would love to spend a hour or two asking her questions.

What a superbly-presented lecture on a long-debated mystery.

22:20 you get this animation if you think a particle wave moves up and down like open water, and not back ad forth like the tide.

Wow. That was so clear. Thank you.

Thanks you, Claudia de Rham, for explain to us your original point of view about gravity. There is only one tetradimensional alternative theory to General Relativity. It's called "Teoría Conectada" ,and I want introduce to you. Gravitational potential is a new potential no equal to spacetime metric, like occurs in General Relativity. Movement equations are not geodesics, the are now equations (84) in the next link. Thanks you so much! DEPENDS GRAVITATIONAL ACCELERATION ON VELOCITY? Argumentative schematism of Einstein's General Relativity (each step is a consequence of the preceding step): 1) Einstein's Equivalence Principle 2) Gravitational motion equations: geodesics DU = 0 3) The gravitational potential is represented by the spacetime metric itself: which guarantees, since the covariant derivatives of the spacetime metric are null, that the gravitational motion equations are given by the geodesics DU = 0 of the Einstein Principle of Equivalence 4) Gravitational Field Equations: These are the so-called Einstein Equations, which are built on the prejudice that the tetradimensional gravitational potential is represented (again in accordance with the Equivalence Principle) by the spacetime metric itself 5) Solution of Einstein's Equations for the symmetrically spherical stationary gravitational field: Schwarzschild metric 6) Zeros and mathematical infinities in spacetime metrics. "Broken" spacetime. Theoretical prediction of black holes and event horizons Reasonable doubts: 1) What would happen if the four-dimensional gravitational potential was not represented by the spacetime metric itself ? : vixra.org/abs/1510.0137 2) What would happen if Einstein's Principle of Equivalence were not rigorously true? : vixra.org/abs/1510.0135

She does a great job explaining the gravity of the situation.

Sounds like she is the Max Planck of gravity: she quantised its reach

Hello.This is RU-vid channel is the best thing since sliced bred! Take very good care of yourself!

when a photon is detected, it's carrying information in one direction. when a 'graviton' carries information, how are both distant masses entwined?

The best lecture on Cosmology I have ever listened to! Absolutely brilliant!!

Can someone explain to this layman? Vacuum energy was expected to expand space much faster, but it doesn't. Then we decide to constrain the reach of gravity to solve this. But doesn't this go the opposite direction? Gravity helps hold the objects together, how does restricting it help explain a slower expansion? I heard something close that they only have to consider the vacuum energy over the reach of the gravity, but that leaves me with more questions

Thanks for explaining it in such a way that everyone could understand.

An unusually bombastic title

Very nice! I'd say that gravity having a finite reach goes hand in hand with the vacuum being non-empty, or that it's having some energy, that it's being non-null (mathematically). Because, in math, if you eliminate "infinity" then you have to eliminate its inverse: "zero". The world we live in is finite, and if you accept that then nothingness needs to be eliminated as well. Very nice presentation, thank you.

Well, this is something really new. :) 2:42 text: "your cells are not torn or pushed apartheid."

If there is a Planck length, I don't see how gravity could be both continuous and have an infinite extent.

the modern version of aether. No, it does not have a "wind". Never did. Yes it has energy 1/137th which is where the cosmological constant comes from.

I remember the day I started to understand gravity and straight lines,it was like a eureka moment.

Practically gravity already has a finite reach. When the curvature of space is smaller than the Planck length, it's negligible.

Here's a few superpostioned opinions I had while listening to this fascinating presentation. A doctorate in cosmology as well as cosmetology is indeed very impressive, so I am certain the good doctor has viewed any serious discussion remotely similar to my rambling musings, from all the various mathematical languages and personalities, but i shall mutter a few here: All objects in orbit travel in a linear trajectory. It is not paradoxical that by moving in a straight line over a brief distance, one may return to the original position due to the curvature of space. Time does not elapse at a uniform rate across different locations; however, the variations are negligible when one remains in proximity to the reference point for time comparison. These minor discrepancies in the flow of time give rise to the most profound phenomenon observed: gravity. What distinguishes an object that recedes at an increasing velocity with distance from the perception of time accelerating as an object moves farther away? If I were to experience free fall within an elevator, how would I ascertain that I am not merely in a weightless state, devoid of gravitational influence? It is simply a matter of perspective. If gravity indeed influences the passage of time, then time is affected dramatically and solely within these filaments of energy or dark energy, close to where the most matter is. The observed acceleration of cosmic expansion, or the perception of time advancing more rapidly with increasing distance, may be attributed to the insufficient strength of gravity. This phenomenon could be a consequence of the majority of matter being concentrated within black holes, thereby diminishing the curvature or intensity of gravitational effects over extensive regions of vacuum energy production. The energy of the vacuum, as represented by the Higgs boson, can exert influence on other particles but remains unaffected by gravitational forces. The abundance of this vacuum energy results in an expansion rate that is 28 Oom greater than the gravitational pull, driven by quantum fluctuations. Our observations reveal a greater prevalence of vacuum energy than would be expected from the observed void, suggesting that approximately 99.9^28% of all energy in the universe is comprised of vacuum energy. The phenomenon of spatial separation occurring at a velocity exceeding that of light, for us, shall transpire over time; however, but we are situated near sources of gravity that counteract this dark energy. Nevertheless, this vacuum energy is more abundant in regions beyond our immediate vicinity. This observation implies that the rate of expansion should be slower in our locale and more rapid in areas with a higher concentration of vacuum energy, situated farther from our position. Every object, regardless of its distance, influences the linear trajectory of all others, also resulting in variations in the passage of time at different locations. If the influence of gravity were finite, the necessity for such a substantial amount of dark energy would be diminished. Conversely, one could posit that time progresses at an accelerated rate with increasing distance, necessitating an infinite reach for gravitational influence. The act of accelerating against the effects of dark energy implies that the energy expended concurrently causes time to elapse more slowly for the individual exerting the effort, while appearing to progress more rapidly to an external observer. Thus, the observed differences in the passage of time at greater distances can be likened to the act of resisting dark energy, which sustains the expansion rate at approximately 28 Oom. I don't know if this is what we are observing or what I am hallucinating.

Existence is the most universal phenomenon that exists.

A pleasure to watch you quantumly fluctuate along the time direction, like a longitudinal wave of harmonic oscillators driving consciousness.

Does anyone listening have a hope of understanding the curvature of space and time?

For Claudia. It is clear that you exemplify perfectly - and have already fully discovered and conquered all there is to know about "Cosmetology"!!! Thank you for focusing on cosmology and 'gravity'!! ❤❤❤😊😊😊

gravity only acts at the speed of light, so as the light arrives, we can calculate a location for the source of the mass with which we are currently trading gravitational attraction. If a body is beyond our vision, outside of OUR visible universe, because those objects are accelerating away from us faster than the speed of light, then we don't currently trade gravitational attraction, and gravitation therefore has a limit, because essentially objects beyond our vision cannot transmit their location. If I'm right, then shouldn't there be a sliding scale of gravitational attraction based not just on the mass, distance and direction, but also on the speed of separation? It means that the gravitational force equation requires a new term (1-radialvelocity/c), which may eliminate the need for dark matter.

Is it cosmic acceleration, or is it Cosmic Force? Force is an outward moving centrifugal, divergent curve linear vector that ends in the total impotence of energy as Space which is aethers shadow and not a thing. So force is the Loss of Power which is Aether Disturbed which has a return vector Acceleration (gravity) which is the opposite of Force. It is inward, converging centripetal, inertial towards Non Spatial, Non Cartesianal Rest/Aether/Pure Potential/ Power/Source and that is why we cannot see it or measure it. We can only see and measure its disturbances vectors and return vectors.

In any discussion of Unified Theories, Gravity, Electromagnetism, and the Strong & Weak Nuclear Forces are taken as the four fundamental forces of nature; the first two are part of our everyday, macroscopic experiences. It's curious that Electromagnetism has been uniquely excluded from Cosmology. It makes sense to use all of the tools in the toolbox. "Magnetohydrodynamics & Plasma Physics" is discussed in Chapter 10 of Jackson's "Classical Electrodynamics" (2nd edition). Revisiting the concepts in "Cosmical Electrodynamics" by Alfvén & Fälthammar, and "Physics of the Plasma Universe" by Peratt deserves attention, especially in light of contemporary observations from JWST and other observatories, for example.

The mainstream seems to really love the gatekeeper role over what possibilities create our reality. To think, Bruno Giordano... May we all keep an open mind and remember, its because we think we're the center of the Universe, that we're wrong. ✌️ Excellent presentation and thank you for sharing this. 💯

Very interesting. I was wondering who may be delusional over theories about gravity and dark energy. Certainly, most of my focus is on whether gravity can be quantized. But that perhaps gravity’s reach is finite and that dark energy resolves for this discrepancy makes sense. I’m looking forward to the refined study of gravitational waves as to clue us into its reach.

I love your background. I think I get what it’s saying overall, lol. Love it! Had to pause for a long while and read. I love the repetition in equivalence random or not.

Incredible

When looking at space-time, why is time overlooked? Are gravity waves just ripples of time distortion?

Gravity with a finite reach should be fairly "easy" to simulate in a computer model. Has this been done?

What is the distance at which the effect of gravity is lower than the quantum fluctuations of the position and momentum of elementary particles ?

I wonder where 'dark energy' is supposed to be sourced from, given the perpetually accelerating expansion of the universe.

I know a bigger discrepancy than the one she mentioned in the whole of physics: the mass of a cm3 when calculating vacuum density is 10^94 g/cm3 (the energy of as many planck spherical units as fit in a cm3), while the observed vacuum density is 10^−29 g/cm3. There you go, a bigger discrepancy in physics.

Simple to understand. Gravity may be limited over distance. Like strong and weak forces. Big distances but limited. So expansion of the universe is then as it should be. 😊

For Claudia: This may be a dumb question or observation, however, every time physicists speak of "curvature of space & time" they also speak of the "fabric of space time" & provide the sort of graphic you have - showing "mass" sphere bodies bending space time fabric. My question is simply this. Is this graphic illustration "limited" or "inadequate" to the extent that actually "space-time curvature" is not actually on a flat horizontal frame/plane - but rather, is in all directions and on a fully enveloping 3 dimensional 'medium'. (ie as if the spheres were generating curvature as they passed 3 dimensionally through space. In a simple example as if a ball travelling through some form of semi solid/semi liquid medium - was able to create in the particles of such a medium - in 3 D - the sort of "curvature" shown in graphic??!! I hope that makes sense! Do please perhaps let me / others know of your thoughts and 'clarification' if necessary of the graphic of "space-time curvature" and its association with gravity (gravitational force / 'graviton'(matter) and the limits of gravitational force. I find your theory fascinating as in a way it actually seems to hark back to the huge 'debate' which Sir Isaac Newton had with [????] which was about whether there had to be some "physical substance" between heavenly bodies in order for them to be subject to forces moving them - vs Newton arguing that the gravitational force was operating without any such concept or necessity of there being some 'physical' medium through which forces could operate on and move heavenly bodies! PS: I think your mastery of 'cosmetology' is plainly evident in the absolutely elegant fashion you are so perfectly wearing. (sorry -i'll admit - i have an innocent crush on you as an amazing human being!! ❤❤)

4:56 "...for thousands of years we thought the Earth was flat..." !! This never happened; no one, including the Greeks thousands of years ago, thought the Earth was flat. Only nowadays we have idiots thinking Earth is flat. How can de Rham not to know this?

The gravity representation using the rubber sheet is a bit of a misrepresentation. We live in a 3D world and the physics is in with us. The Sun's gravity field has to be seen, accepted as being 3D. The indentation of the rubber sheet has to be viewed from every position - the space around the Sun is 3D, the gravity is affecting all that space. Getting you head around something that is already invisible makes seeing things accurately a real bitch.

I like to think of gravity being eleastic. When gravity is present, space streches and have greater potential energy. If gravity works on a multipliclative scale, black holes which curves space on an infinite level could cause sufficient energy to power expansion.

28 fold discrepancy! Almost like the universe is laughing at our ignorance!

I am going to listen to this again and again just to hear her talk. ❤

21:46 "To be sure mathematics don't lie, so if you come up with a mathematical proof, it must be correct." What? You mean provided the assumptions are correct.. right? To be sure Prof De Rham is very smart. And she certainly moves at high speeds.

How do we know that it's not light that is losing energy as it travels through space but instead space expanding that causes the light wavelength to expand?

A very good speech!!!

Great video, When i think of the effects of mass on space is that it is increasing the energy density of vacuum and empty space, this increases the dielectric constant of space and even decreases the space between atom in molecules for example. Gravity will always appear to have a finite reach due to the speed of light/gravity where its effects on us is limited to the observable universe. If space appears to be stretched at long distances from us it could mean as you say gravity we feel is weaker so space itself or it will appear to be not as dense. One of things is we feel weightless being in the center of observable universe, so empty space away from dense objects should be stretched in all direction, like for example in the center of the earth. I would think as we observe objects away from us we would be observing objects that themselves would be in their own center of observable universe, but to us we should see the effects of gravity as the are no longer in our center of observable universe. An example of this would be if we were in center of the earth and observing a light on surface of earth, i would expect to see the energy/dielectric constant of space to be more dense so time woul appear to move faster. But this effect would appear to be contrary to what we see when we look at distant objects.

Neolithic man understood that the Earth was a globe, evidence found in stone circles precisely positioned relative to the sun, moon, Venus and stars confirm they understood the circicular motion of nature that surrounds us. They had the same mathematical ability as we have today. Their understanding was passed on in songs and performance, these teachers were known as druids. Understanding was lost in time and it is in writing that our understanding is re-established. Flat earth is relatively new in the scheme of things. Understanding of gravity however is new to us. Go Newton, come on Einstein, you guys rock.

It's an interesting take, I feel it more speaks to die-hard relativists that may be relucant to quantizing gravity. Unfortunately QM has a lot of effective tools on how quantizing something turns into behavior, but, emphasizing: although the plain result is it won't work (acceleration is increasing, not flattening) it does 'let more math in' in a way which might be constructive.

What about the part where the kids get eaten by bears for mocking the bald guy ? That’s one of my favorites .

I know it's not right or socially acceptable, but I must say it's very difficult concentrating on what's being said when it's done so by such a lovely woman.

All of that education and she still has a great sense of fashion.

It's comforting to know that there is never 'nothing' happening anywhere.

I still prefer my theory: There is a conservation of gravity similar to the conservation of energy in that if you take from one, it has to give in another. So if the mass that are PULLING space-time to create attractive gravity are "taking", then something somewhere else has to "give back" to balance it all out. The "giving back" is the space-time in-between galaxies and the rest of the universe that is pushing things away through a force that appears REPULSIVE in nature.

Very interesting. I think this will spin of a number of new theories, and may be give us a better insight into how big the universe is or if it is just infinite. Is the universe expanding or is it simply returning to its initial state before the big bang.

Started to watch this video to find out something new, but no such luck. Just the same chew again and again.

Very sensible hypotheses. Rather than labelling our unknowns as Dark Energy, the thought that gravity and understanding the forces of nature will explain the universe's origins, behavior and eventual fate just makes sense to me.

Here come the comments of the aluminum hats 😂

It might be that gravity is in fact unlimited in range, but that at a certain distance, it becomes too weak to effect any physical change, even at the smallest possible scales.

One of my Chinese students here in Shanghai wrote on their homework that the Cosmetic Background Radiation is evidence for the Big Bang.😂

No idea what she said but i enjoyed it

Click bate title

Awesome presentation!

did not listen yet. title is wrong.

Is the Universe spinning? What about a ring bang boom? The Universe collapses to a rung singularity beam like a particle collider around its boundary, and implodes into the universe of tomorrow. A Universe that remembers its past. A Universe we can speak to and tell them who we are and what we were, and if they are advanced enough, what we know.

Who else noticed that some of the equations behind the speaker contain errors?

Since high school physics I've always had the picture of a mass pressing a membrane down...but a consequent rise in the membrane around it. In other words; to me, symmetry means a spontaneous creation of anti-mass for every mass, the antimass a diffuse bulge, pushing all stars into strings around the bubbles.

Summary of her point: If gravity was not thought of as infinitely far-reaching, but limited, then some calculations could work out better.

It makes a lot of sense... At the very least probably the stretching of the fabric of space-time when closer to other objects, counteract or disipates the gravity impact and reach from other farther... Observations are key and if the observations don't match with infinite reach we may be on the face of a more simple explanation that matches our reality

If spacetime is itself quantized, then gravity should have a minimum limit (one quantum of gravity).

your amazing! we love your work! long live the death of the ghost!

When we speak of gravity having a finite range, does that mean its effect goes to zero at some range, or that its effect at that range is masked by some other effect?

Amazing explanation!

Isn't the reach of gravity limited anyway, due to the expansion of the universe, in the same way that light is? Or are we saying that gravity doesn't even reach as far as the edge of the observable universe (from our point of view)? Or Are we saying that the reach of gravity is limited somewhere past the edge of the observable universe, something that would be impossible for us to observe anyway, because of the expansion of space?

An interesting avenue of investigation is to consider what the effect would be if gravity is a repulsive force, rather than the accepted attractive force. If matter acts as a gravitational shield and everything is pushed towards massive objects like the Earth or Sun by the effects of gravity pushing inwards from the surrounding universe, would the day to day effects we observe be any different? However, for widely separated objects, they would have a tendency to fly apart from one another towards the edges of the observable universe.