swansont

Fired for giving plausible-sounding but false information? The deuce, you say.

No, it’s not observable and not measurable.

Is it? Under what conditions do you have phase velocity ≠ group velocity? There are observable quantities whose product is not physically meaningful.

Something like when you have two possible answers for a square root. If one isn’t physical, you ignore it.

Not being an observable is distinct from something that isn’t directly observable. And observable means it can be measured, or the resulting effect can be measured. So virtual photons can be confirmed because the model makes testable predictions. Dark matter in inferred because of its gravitational effects, which can be measured. At the end of the day, agreement with experiment is what matters. What are the measurable effects of phase velocity?

Do you know what a derivative is?

Since the blue shift of Andromeda can be directly measured, this question makes little sense. See e.g. http://www.astrosurf.com/buil/redshift/demo.htm I’m sure papers have been published with other measurements If you want to know about significant digits, all you have to do is ask.

If there’s one reservoir there are likely more, seeing as people hadn’t been looking, and the main issue is whether it’s cost-effective to retrieve it. How much there is is important in that context, and not in relation to how much is used. It’s not like hydrogen in general is a non-renewable resource.

Goo goo g’joob But the walrus was Paul (citation: Glass Onion, The White Album)

Does he have an onion tied to his belt, (which was the style at the time in some places)?

Engineer has been banned for repeated and persistent thread hijacking

Can music save your mortal soul?

! Moderator Note Matter wave discussion has been split https://www.scienceforums.net/topic/132885-matter-waves-split-from-photon-is-massless-why/

Not an adult, or not the whole thing goes in the bag? https://trishansoz.com/trishansoz/waltzing-matilda/waltz.html “The swagman is starving. He hasn't eaten in days. So he catches the sheep, kills it, eats what he can, and stows the rest in his backpack (tucker bag).”

Not in precision or accuracy, in reality, but one generally postulates an ideal system, and in that regard, how much would it matter? An ideal clock has whatever precision and accuracy is required.

It typically ends up heating the material in the vicinity. If you dropped 1 kg mass a distance of a little over 40 cm, it would transfer ~4 joules of energy. If the impact was on a 1 liter container of water, it would raise the temperature by about 0.001 degrees C (heat capacity of water is 4.186 J/gK, and there are 1000g of water per liter) That’s not a big temperature increase, nor does the situation you describe involve a humongous amount of energy. But you could scale this result according to whatever details you want to. Hitting the ground will involve a smaller heat capacity but a larger mass.

Bold and ALLCAPS are used fr emphasis. When all of the text is presented that way, it’s considered yelling.

You appeared to cite it. Did you just make that number up? And we’re supposed to take your assertion as fact? If you answered my question, or read what Markus posted, you’d see that such pedestrian speeds are small compared to recession values of distant galaxies. Ignoring it in certain calculations is completely reasonable, e.g. when it’s smaller than uncertainties in the result. If you only know z to one or two digits for z >1 , ignoring a speed with z ~ 0.01 is not a problem, if you understand how significant digits work.

You were talking about galactic redshift, which is due to expansion. As I said, you do some math and separate the effects. If we know our velocity, we can subtract it. As has already been pointed out, it’s a small number with respect to distant galaxies Again, one needs to do the math. What is the red- or blue shift for 300 km/sec? z=?

Orbital motion is not expansion. This is a pretty fundamental issue; motion constrained by being gravitationally bound systems is not expansion. Orbital motion is quite definitely from being gravitationally bound. I’m sure you aren’t the only one. Some people can do math and distinguish these two components of motion, and the effects that arise from it. Andromeda is part of the local group, and so is gravitationally bound. Also not subject to expansion. In however many millions of years, anyone versed in the appropriate science will be able to figure out that Andromeda (or whatever is left of it) passed by/through us.

Moving 222 km/sec is (largely) tangential motion, while 120 km/sec wrt Andromeda is not. I think the most prominent issue has has to be discerning what orbital motion is, why that’s not the same as linear motion and why it has nothing to with expansion, since you seem to be confused about this.

AI is not a valid resource for science discussions. AI has no expertise, and no actual intelligence. You can ask all you want, but it’s not really much different than asking somebody at a bar. The rules require citing mainstream science in discussions, and AI does not limit itself to that (i.e. it makes stuff up) GR makes specific predictions, and they have repeatedly been shown to be correct.

! Moderator Note You need to provide more context for this

! Moderator Note Replies need to be relevant to the discussion (rule 2.5). Videos, too, and you have to explain what that connection is. (rule 2.7)

If it were a quote I’d want to know the context of it. In regards to this discussion, it’s flawed. And I notice you didn’t answer the question, or invite any discussion as to why it’s flawed (and it’s things like this that gets your threads closed; it’s soapboxing, which is against the rules) It’s trivially wrong, as Newton had a model for gravity that did not invoke curvature. It also contains a tautology, since the currently accepted model is spacetime curvature, but is it the only evidence? Models make specific predictions. Time dilation and bending light depend on a particular model, and not merely the existence of gravity. And to echo what Markus says above, models are accepted based on all the evidence, not just one data point. Same goes for rejection of flawed models.