# Danijel Gorupec

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1. ## Do gravitational waves distort time?

The derivation you are mentioning... is it considering some sort of plane gravitational waves, or more general? As I understand you, you are also talking about near-observer perturbations? Otoh, the array of clocks, I was mentioning, is distributed.
2. ## Do gravitational waves distort time?

I was indeed interested in weak gravitational waves... I would be surprised if the theory only predicts disturbances in spatial dimensions, and not the time dimension. Because I am under impression that the theory treats space and time on more or leas equal footing. Anyway, I am now thinking about what you said, if gravitational waves indeed can cause only (or predominantly) spatial disturbance, can then there exist a different type of gravitational wave that only (or predominantly) causes time disturbance? @swansont Thinks for the link.
3. ## Do gravitational waves distort time?

As a gravitational wave passes though a constellation of precise clocks, would it be possible, at least in theory, to detect its passage by measuring time difference between clocks? If so, is it harder to make such measurements than to measure spatial distortions?
4. ## Could A Space Shuttle Get To The Moon?

Could two or more space shuttles do it - by refueling in the orbit? At least an one-way trip... You park one shuttle in the orbit, and then use other(s) to bring more fuel.
5. ## The Nobel Prize for Physics has been awarded

Does it mean they are using gamma ray lasers? Can you see anything in gamma light without destroying it?
6. ## Measuring the distance to the Moon from a photo of a solar eclipse

If I understand the task correctly... it is to estimate the moon distance on that exact day (it should be somewhere between 362600 and 405400km). You can take the moon and sun diameter (both fixed) from any external source.... The interesting part, imo, would be to estimate the error of your calculation.
7. ## Plagiarism, kind of

I suppose your relative is aware that it is very easy to check if he sourced the answer from the internet. So, he probably did not have an intention to fool you... I guess he would change the wording if he really wanted to deceive.
8. ## This frog just swallowed a lizard

Did you watch as it was happening? Was it fast or slow? I recently saw a video of some kind of sea slug catching a sleeping fish... by very slowly enveloping the fish in some sort of extendible bag... I was very impressed, but forgot to remember the slug name to learn more about it.

10. ## Why "even light"?

Hmm... I was supposing that 'not even light' is simply used to explain why it is called a 'black' hole. Most of the time, however, I guess, the phrase is just repeated without much thinking.... maybe we should not overthink it either.
11. ## Turning direction and thread effect on terrain...

Afaik, the one way will aid to directional stability, the other one will hinder it. When ribs push the mud outward, it aids the directional stability (that is, forces try to straighten the tire path). Normally, on a tractor, you mount the tires to push the mud outward if tires start slipping while the tractor is pulling forward. [But, I guess, if you use the tractor to brake a pushing cargo, such normal rib alignment might make your steering more difficult.]
12. ## How does a wheat germ acess nutriens from endosperm?

Hmm... searching further, I found the following quote on Wikipedia: "The larger basal cell will give rise to the suspensor, which connects the embryo to the endosperm so that nutrients can pass between them." ( https://en.wikipedia.org/wiki/Embryo ) "suspensor" seems to be a term, so I found several links explaining it in some details (googled for 'seed suspensor'). Two of them are listed below: https://research.mcdb.ucla.edu/Goldberg/research/Pdf/sdarticle.pdf https://en.wikipedia.org/wiki/Suspensor Quote form the first link: "For example, the suspensor pushes the embryo proper into the endosperm cavity and connects the embryo proper to surrounding maternal and endosperm tissues - serving as a conduit for nutrients and growth regulators required for embryonic development" It seems, the 'suspensor' might have an active transmission mechanism, but the nature of it may not be known yet. However I am not sure if 'suspensor' is really the answer to my question because: the 'suspensor' seems to only exist for a very short period during the very first phase of embryo growth - I am not sure if all the nutrients from the endosperm are absorbed during that time. The 'suspensor' might only consist of a few cells. Subcellular outgrowths might have a role in absorbing nutrients (if I understood correctly). I also guess, something there, 'suspensor' perhaps, should release enzymes to cut the starch into simple sugars. For my second question, I didn't find a valid answer - from the internet readings, I cannot deduce if plant root can absorb glucose or not. I also cannot find any info if plant roots can emit enzymes to transform starch into simple (absorbable) sugars. However, when I think about it, I would guess the answer is NOT - if plants would be able to absorb starch through their roots, I would expect to see more 'predatory' behavior among plants. Anyway, I am abandoning this investigation as it seems to require a knowledge well beyond my level.
13. ## OceanGate Submersible Goes Missing During Titanic Dive

I would expect more likely for such a sub to surface than not. Hull implosion seems to me like (it should be) the least expected fault.... In fact, I considered the underwater search like some sort of wasting resources that could be used for the surface search. That said, I am unpleasantly surprised that the sub did not have any orange-colored part. Cannot think of any reasonable explanation.
14. ## How does a wheat germ acess nutriens from endosperm?

When a plant seed germinates, how exactly does a germ access nutrients from the endosperm? Does it grow like a tiny roots into the endosperm? Can plant roots absorb starch (or at least break the starch into sugars before absorbing)? For example, if I mix wheat flour into ground and then seed wheat there, will this wheat be able to access nutrients from the flour?
15. ## How does a placebo work?

Self-reported or measured symptoms?
16. ## Mushy questions about gravitational waves

Thanks for your comments... I didn't expect strict answers in the first place. For me, the most interesting part in your comment was about 'redshift' - are you talking about measured or calculated effect?
17. ## Mushy questions about gravitational waves

Thanks Markus... Because gravitational waves carry energy, I would suppose that they also carry momentum (Or not? I have a hard time imagining this). If gravitational waves do carry momentum, and if some source is emitting gravitational waves directionally (like a directional antenna), then I suppose the source will be receiving impulse in the direction opposite to the direction of emitted waves (possibly propelling itself through the space).
18. ## Mushy questions about gravitational waves

Few questions based on the analogy with light/sound waves. I suppose most cannot be answered strictly, but at least give me your hunches. 1. Should I expect that gravitational waves may reflect when they hit some sort 'wall'? Can such wall exist? Can we have phase-change and non-phase-change reflections? Can you suggest a 'wall' (either active or passive) that causes phase-change or non-phase-change reflection of gravitational wave? 2. I suppose gravitational waves can interfere? Is this a linear or non-linear process? 3. Can we imagine a standing gravitational wave? Can we imagine resonant cavities for gravitational waves (possibly allowing amplification)? 4. If we have multiple controlled sources of gravitational waves that act near-coherently, can we employ beam-forming - thus making a directional source of gravitational wave? 5. If directional gravitational antennas are possible, will such an antenna experience an impulse to the opposite side of the main gravitational lobe?
19. ## dark matter question

But do we have any estimation how much denser those galactic halos are compared to intergalactic space (regarding the DM density)? I mean, did galactic DM halos just started to form or is it that all the DM is already clumped in galactic halos?... I guess, from galaxy rotation curves we can only infer the difference in those densities, not the absolute densities (thus we can only infer the lower limit for the amount of DM)? I think Genady once argued that general relativity can set an upper DM density limit, even if the DM is near-uniformly distributed through the whole space (although, I am not sure if the dark energy factor would mess up such an calculation).
20. ## Does gravity effect how much energy is required to maintain speed on a moving object with a higher mass than another object?

hmm... I will try to be more careful... Generally, yes.... you generally need to invest different amounts of energy to maintain speed of two objects of non-equal mass in gravitational field. The exception are the trajectories that are always perpendicular to the gravitational force.
21. ## Are human babies the loudest in animal kingdom?

Interesting... at first I would instead expect that calf, lamb and deer babies keep quiet, not to attract predators. Isn't it true that in some animals, mothers can leave their babes in quiet hiding for some limited time? Human babies obviously do not even think about predators, lol.
22. ## Are human babies the loudest in animal kingdom?

Yes, a dumb question, but I am just listening to a baby crying across the village and I cannot remember if I ever heard any baby animal crying that loud... Strange. Are baby gorillas equally loud when crying? As far as I can remember, baby chicken can get very loud - possibly only quieter than human babies due to smaller body size. Are ostrich babies particularly loud?
23. ## Anti-Satellite Weapons

Did they actually test this? My understanding was that all test hits were performed on non-functional satellites that had predictable trajectories - and if the weapon is designed to target evasion-capable satellite, then they tested shit. Are you saying that the weapon has a local sensing system that locks it on the satellite? I was under impression that all guidance is made from Earth. (Because if the weapon does not have any local sensing, then you can still play the game with an 'imagined evasion-capable satellite'.) EDIT: just occurred to me that even if local sensing is employed, they could still easily reprogram the software to miss 'five yards to the left'... and confirm the expected result using the all-mighty earth-based tracking systems.
24. ## Anti-Satellite Weapons

Maybe, but such agreements generally do not hold in case of war. Just brainstorming: maybe we can calculate the critical satellite density that can cause the destructive chain-reaction, then make an agreement to keep the density lower.
25. ## Anti-Satellite Weapons

Why does someone need to actually hit a satellite to test an anti-satelite weapon? You simply imagine a point in space and make your weapon fly through that point at certain exact time - this is a hit. Hitting an actual satellite seems more like an exhibition to me.
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