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Experimental observations matching a model with zero invariant mass. Example: If the photon is not a strictly massless particle, it would not move at the exact speed of light, c, in vacuum. Its speed would be lower and I guess it would also depend on its frequency.

If you mean any given human can survive, then the statement is trivially false, as we have already observed that humans die when it gets hotter, and areas of the globe would be uninhabitable. If you mean humans as a species, and that's all that matters, then this is an argument not in good faith, since nobody is arguing extinction of the species will be the result, or that the impact is limited to humans. If they conclude that the temperature will go up by XºC over some span of time, under some set of conditions, that is neither an affirmative nor pessimistic bias. And, as scientists have discussed positive impacts, your argument to the contrary is moot. e.g. https://www.climate.gov/news-features/climate-qa/are-there-positive-benefits-global-warming Why would you expect anyone to take this "argument" seriously? Because land is evenly distributed on the globe? And arable land is all that matters?

They're basically the same, a few tweaks and they could live anywhere...

In all the years I have watched your posts. This is one of the best replies I have seen. Highly accurate +1. ( Not to say your replies have been inaccurate. I particularly like the ramifications of this simple but profound reply) Fields for example is an abstract descriptive for a group of mathematical objects (scalars, vectors, spinors, tensors) under a geometric basis. In the QFT formalism which the Hobbs paper supports the field has probability path integrals (Feymann path integrals) Wavefunctions of the Schrodinger equation involves probability functions. The pointllike attributes can be described by the DeBroglie or Compton wavelength. In all the three dynamics they break down to descriptives. The OP is correct in that an elementary particle has no corspuscular (matter like ) constituents ie not little billiard balls. However particles can be described as field excitations which has both point like and wave like characteristics(side note another descriptive I have seen you often state. Physics doesn't describe reality) is also very apt. Physics describes what we can observe. Though it also speculated on the unobservable for example virtual particles.

One lesson that one can take from that article is that waves/particle/fields are not what these thing are, they are just how we describe them. The map, not the country

Right now, amid the covid-19 global pandemic and climate change and so much more, locusts are also decimating crops and amplifying starvation across the African continent. They’re everywhere and they’re hungry and people are hurting with hunger. What would it take to catch the locusts en masse / at scale and use then as a source of protein to feed the hungry? Essentially: Prevent them from causing starvation and use them to solve starvation. I’m thinking of something like a giant fishing net for the air, but am sure there are far better ideas (am not sure, however, humans can even eat locusts, but they seem close enough to crickets). Bonus points if any solution ideas are low cost and scalable.

Because it’s a trick, he’s using a piece of glass not a mirror and that’s his left and right hand and two bowls, you can tell he’s tipping the right hand slightly more, and he doesn’t show the other little tricks in the shot of the “mirror” . I do magic tricks , so simple. Now this same guy is ripping people off by selling a substance dyed with cinnamon

As omnivores, humans have eaten all manner of things throughout history and across the globe. Modern incarnations include bush-meat, cats, pet rabbits, all the various bits of an animal's genitalia and even bat soup. They may not sound appealing to some, but others regard them as nutritious delicacies - It's just a matter of taste! As for catching insects for food, are you aware of the Mali lake flies? Not exactly on an industrial scale but the kids love it and the biscuits are pretty tasty. https://m.youtube.com/watch?v=Qs33k1b6N_A

There have been so many "last" straws, I have lost count. Just a few months earlier, a black jogger was murdered by gun-toting folks but that was not all, while he was jogging he accrued at least two 911 calls, one of them calling because a black guy was running down the street. I am not sure whether this incident will be remembered as extraordinary either. There have been so many mind blowing incidences. Remember John Crawford III? He was killed in a walmart after handling a BB gun in the toy aisle while on the phone. You know, in a store where they also sell real weapons in an open carry state. Police came in after an idiot made a 911 call about a black man brandishing a gun. He was killed before he could he could even react. No charges were laid. Philando Castille is another prominent incident. I submit that these incidences will imprint folks very differently. Even if it ends up non-violent, there have been a string of 911 calls on black folks who did nothing out of the ordinary. Sure, this case seems to be more gruesome than some of the others. And perhaps more importantly, it has been captured on video but many folks do see it as part of larger system of disenfranchisement. The police is not felt as protective agency, at best it is seen adversarial. A common interaction can turn lethal, with higher frequency for some folks (yes, not exclusively, but if embedded in historic experience it sure is heavily slanted). The measures of securing wealth have been systematically moved out of reach. Political powers have been and are continued to be minimized. And to add insult to injury, folks in power deny the experience of minorities, especially of black folks.

! Moderator Note Careful, we don't disparage whole groups here. One of our current admins joined when he was 11. Not sure how many degrees he has presently, but I don't think he's old enough to drink legally.

Photons also have left-hand and right-hand polarization. https://en.wikipedia.org/wiki/Circular_polarization

Here's a simplified scheme: Gauge bosons (spin 1 or 2) --> photon, graviton, electroweak bosons, gluons Fermions: Leptons (electric charge) and quarks (spin 1/2) (fractional electric charge plus chromodynamic charge) Fermions are weird in that they distinguish left and right also and quarks (nuclear particles) are weird in that they can't escape to long distances because of confinement due to chromodynamic charge, similar to electric charge but far more complicated There are more peculiarities...

No, electrons are peculiar in an entirely different way: their spin.

"Having mass" is shortcut from "having rest-mass" these days in scientific circles.. Rest-mass (aka "invariant-mass") is strictly tied to rest-frame. https://en.wikipedia.org/wiki/Rest_frame https://en.wikipedia.org/wiki/Invariant_mass

Photons do not have mass, although you can define mass for a composite system of two photons that are getting farther and farther away from each other.

An individual photon have zero invariant mass and is referred to as massless.

Nope. But they do have momentum.

I have passively followed this from the sidelines due to limited knowledge in the area but I've learned a few things*. Are you sure? There are now 10 pages of excellent examples and objections from several experts in the field, none of which seems to bring you closer to the desired understanding. I've browsed through the thread again, each time a critical argument is added the standard type of response is: What prevents you from understanding the objections related to your idea while at the same time you seem capable to understand several other complex concepts of physics**? What prevents required new tools from being added? I may have some ideas about (over-)simplified analogies as a complement to the expert explanations given so far but at this time I'm not sure if that is what you are looking for? *) @Mordred's "What curves is the principle of least action" certainly trigger some thoughts, I'll try to study that, check if my intuitive understanding of that single line matches the mainstream science. **) I lack your level insight into GR but I can still understand much of the discussion.

Simplify the expression all the way to the end, given the relations you posted earlier: \[g=\frac{c^{2}}{r}\left( 1-\left(\frac{t_{0}}{t_{f}}\right)^{2}\right) =\frac{c^{2}}{r}\left( 1-\left(\frac{t_{f}\sqrt{1-\frac{2GM}{rc^{2}}}}{t_{f}}\right)^{2}\right) =\frac{2GM}{r^{2}}\] As r->0, the gravitational acceleration increases without bound, and diverges at r=0. This is clearly not what we physically observe, since a test particle at r=0 experiences no net acceleration at all; yet it is still time dilated wrt to some external reference clock at infinity. I’ve been thinking about this some more, and I was actually wrong on something, and need to go back on it - even in Schwarzschild spacetime, you cannot specify all aspects of gravity with time dilation alone; you need at least a vector field of some kind. Consider two test particles (with their own gravitational influence being negligible) which fall freely side by side, but separated by some distance, towards a central mass. They fall at the same rate, so at every point their radial distance to the central mass is the same, hence they experience no gravitational time dilation with respect to each other. However, as they fall, their trajectories will start to converge, i.e. they approach each other as they fall towards the central mass, and eventually collide near r=0. There will be relative acceleration between the test particles perpendicular to their radial in-fall, even though they are not time dilated wrt to one another. This is because even in Schwarzschild spacetime there is tidal gravity - all radial free fall geodesics converge at r=0. You can capture purely radial in-fall via time dilation alone, but not these tidal effects. So even in simple Schwarzschild spacetime this idea ultimately fails; if you use a single scalar field to model gravity, you do not obtain the correct free-fall geodesics which we observe in the real world (unless the free fall is purely radial, which is trivial anyway). In fact, if you write the proper equations of motion for light using only a scalar model, you will find that there is no gravitational bending of light around massive objects, which is of course contrary to observational evidence (see Misner/Thorne/Wheeler, Gravitation, §7.1).

Wasn't meant as proof of relation to AGW. It was meant to show that adaptation/evolution is a slow arduous process, that, quite often fails, and leads to extinction. Again, to emphasize the difficulty of adapting to rapid change, a lot of dinosaur species could not adapt, and died off, but not all did. A lot of small mammals/marsupial did survive. Along with a whole bunch of small dinosaurs, that you can probably hear 'chirping' and flying outside your window.

There are no particles, there are only fields - Art Hobson. https://arxiv.org/ftp/arxiv/papers/1204/1204.4616.pdf

Dilbert’s always good for a laugh, but here IMO the cartoon conflates two distinct topics: 1) Are we free to choose as we see fit or are we instead meat robots (walking/talking bags of mostly water) controlled by chemistry? ...and the other: 2) How should society address behaviors that fall outside of locally accepted norms and how best shall we ostracize others who put their neighbors at risk, especially if the person committing the act lacked choice? The second attempts to use an off-topic but related situation in an attempt to highlight logical hypocrisy, the first reminds us that none of these discussions will lead anywhere if we can’t start with and remain aligned on shared definitions of terms. On what is “me” and what is “free” we must all first agree.

What curves is the principle of least action which relates the potential of the field to the kinetic energy of the particle. If you really want to understand curvature then you need to study the Principle of least action with the geodesic equations. (Do not mistake a field as a medium) a field is an abstract descriptive of values or mathematical objects under a geometry descriptive.) Of course it does. Spacetime has no refractive index... Particles behave in accordance to how they couple with a field or other fields. The couplings is what lead to the mass terms. Mass is resistance to inertia change.

As long as there is Oxygen around it will catch fire, once it is hot enough. On a hot sunny day, you could start a fire with paper and a magnifying glass.