I like this thread because there are people in here who debunk this stuff. It's happened several times already. I want the debunkings and explanations because they're fun and interesting.
Ok, I’ll be nicer. I’m very used to dealing with some of the most unreasonable pushback on some of these topics and that causes me to be very aggressive about it, perhaps too quickly.
Like this, right? I don't get it, but I want to get it, because in my brain what's happening is they're essentially bouncing light "the same distance" both ways, but it comes back different times because we got hit with a gravitational wave in the LIGO experiment that made the distance "shorter" in one direction, right?
Would that not have happened under the same circumstances under the MM experiment if they also experienced a gravity wave at the same time?
I WANT TO LEARN.
You actually understand the basic premise of both experiments just fine here. Yes, the basic idea is that two beams of light (or any wave) traveling different distances will interfere when recombined. This phenomenon is evident in all waves, including those in air and water. A Google search for “water wave interference” produces many terrific demos of this.
Your question here about why gravitational waves were not detected in the MM experiment is perfectly valid, and is the sort I’m happy to see because it gets to the physical setup of the experiment and the evidence rather than wishing to substitute one explanation for a preferred one without much standing. In reality, the gravitational field, just like the electromagnetic field, is a very active sea of waves sloshing about. But gravitational waves, like the gravitational force itself, are profoundly weak. For the LIGO experiment scientists were searching for the most powerful waves and even then the expected deviation was less than the width of an atom over four km of travel. The experiment used very sophisticated techniques to mitigate noise, but was routinely shut down over things like earthquakes on the other side of the earth (for those with some laser experience, the entire structure was on the worlds largest pressurized compensation table and the mirrors/detectors were supported by four stage pendulums). Gravitational waves have three possible modes, and a generic wave is some combination of these three modes. That any wave is a sum of modes is a standard feature of wave mechanics. The most common modes only act in the direction parallel to wave propagation and do not affect the perpendicular. Even though it is not possible to arrange your detector ahead of time to be parallel along one arm and not the other, we can just use math to work out the effect at any orientation. Also, detectable gravity waves are produced by massive astronomical events, and massive things are far away from us. In the LIGO experiment, the blackhole merger event happened over a billion years ago and released enough energy to power human civilization for also over a billion years. As the energy is released equally in all directions, over time it becomes more and more diffuse and so even harder to detect.
So, as far as the MM experiment was concerned, there was no fucking way they would observe gravitational defects. They didn’t even use lasers or vacuum tubes, instead using the monochromatic light produced by heated minerals. The resulting interference was not zero (as I misleadingly stated before for simplicity) but was far too small for an aether theory, within instrument error, but actually too great to observe gravitational waves. So the experimental setup in both LIGO and MM was extremely similar and LIGO can reproduce the results of MM, but MM did not have the precision to detect the gravity waves.
Is it that space is like a giant container filled with dark matter that is displaced by matter? Like if a have a big jar of Orbees and shove a marble in it?
Again, this is more in the direction of questions I personally appreciate. First, dark matter is some kind of substance that does not move very much and has varying concentrations (greatest at galactic centers). It is certainly not everywhere in equal amounts. It is also not theoretical. It may or may not be some kind of matter (though there are many hints indicating it is, and the standard model can accommodate it) but there is clearly something there.
Next, space itself. It could be a substance! But in the philosophy of physics, it is permissible to assign physical properties to non physical entities (a classic example is the currently ubiquitous potential theory of differential equations). How we are to interpret that is more varied (a constructionist would say the non physical entity approximates phenomena we don’t understand, a realist might say the field is a real thing). But thinking about it like beads or cells does not align with the predominant modes of thought (but of course that changes). The main issues with this idea are that there’s nothing actually stopping non interacting particles from being in the same place at the same time so that removes the need to think of anything being pushed out of the way. But the bigger issue is that relativity physics, which is deeply built into our best particle theories, gets completely fucked by having a constant number of spatial cells. Relativity theory is extremely good and hard to overturn, and it’s not the sort of thing you’d whimsically dismiss purely because you find an alternative theory more intuitive. Remember also relativity is not just Einstein style but goes back to Galileo, it’s part of the most basic physics in some form. Any alternative needs to be such that it can be explained why it looks like relativity in the right regime, because that’s what the experimental evidence is. All theories of discrete or particulate space lack any kind of physical evidence and as of today are apparently impossible or at best thousands of years away because you need more energy to probe smaller things. As a result, spacetime is still widely regarded as a true continuum until a new breakthrough occurs.
Now, for some thread tax. This isn’t strictly conspiratorial but rather addresses the mysteries and uncertainties in physics, and why it’s ok to question it. There are things in physics and popular science today that are widely accepted that I think have a murky future:
1. The whole of cosmology: the predictions and explanations produced by cosmological physics are incredible, and I like to think we're on the right track with the Big Bang and inflation. Cosmological datasets are the biggest ever assembled but they are challenging. It is the simple reality that all of our observations are taken in a noisy environment. We must filter out noise from our atmosphere, our devices, the sun, and the entire galaxy. Because of the finitude of light speed and the inaccessible energy cost of approaching it for macroscopic objects, we will likely never make any observations far outside our solar system. So how confident should we really be about claims made about interstellar space, much less the origin of the universe? I can tell you from having seen these analyses that they do a good job with very intense statistics, but it is common for multiple very different fits to the data to be produced and many assumptions about the noise are made. I just have a hard time accepting the level of confidence that comes out of cosmology.
2. Aliens, real but impossible to contact: the vastness of space basically guarantees other intelligent life. But what if the light speed problem really never gets any easier with more advanced technology? Everything we know suggests it won’t. So sadly I take a more cynical view on this topic. I think it’s possible for them to send things like von Neumann probes, which are built by other traveling probes, but I’m very skeptical about genuine contact sadly. It’s also questionable what civilization would ever dedicate the resources to producing self replicating probes that can only communicate on the time scale of billions of years. If right now bias is a common feature of intelligent life, why would they even bother? Suppose we settle mars, how do you even control it? We’d inevitably drift apart culturally and biologically with no way to enforce earth power. So any interplanetary or interstellar society with coordinated effort out there is hard to imagine.
3. The standard model: despite producing many predictions that are insanely accurate (predicting the anomalous magnetic moment of a single muon to 10 decimal places in a four year long trial is truly astonishing), it is still a work in progress. Not only is there no gravity, but trying to include it in any standard way makes the whole theory frozen in time. That’s clearly fucked up. It also produces various infinities in important calculations that can be addressed by renormalization in a formal way but feel brazenly non physical. The verification of the renormalization is in physical measurements conforming to the post renormalization procedure. There is no physical evidence of the pre renormed values predicted by theory, only indirect evidence from the broader constituency of the theory. This is truly disgusting behavior. Infinity does not exist, and renormalization is an effective but unreal fix. If your calculations go to infinity, it means your theory has hit its limits. Nature does not get rid of them and doesn’t know how to, because they aren’t real. String theory fixes a ton of this but has extreme ontological baggage that makes it difficult to believe even if some of it may be indirectly correct, including uncomfirmable elements, a theoretical sin.
