studiot

And ?

Thank you for the article. Sorry to pour a bit of cold water, but I have some doubts about the scientific veracity of both the article and its publication site. I am wary of a site that also offers articles like "Did Hubble discover God ? Einstein amazed" and "DNA code points to a creator" The article offers a description of wave motion that we teach as an introduction for 14 - 16 year olds at 'O' level. It has actually been known for a century and a half or more that there are more types of waves than transverse and longitudinal. Some (Rayleigh waves) are even named after the Physicist who studied them. This is not to say that the Hong Kong scientists have not discovered something interesting and perhaps new. But the article does not say what is vibrating in its diagrams. (Plots c and d) Pressure is not a vector. The demonstration device (in picture a) looks like some sort of focusing device. An array of sound sources. It is well known that the sound output is more and more narrowly focused the more speakers you put into a line array. This fact is used in stage speakers. Pictures d and e seem to me to show interference from multiple sound sources. However the group of pictures are entitled negative refract induced by the spin- orbital interaction in momentum space. The false colour appears to give intensity values, but intensity of what ? It does not say. So perhaps the scientists have engineered a clever way to manipulate sound.

Lovely pic +1 Perhaps you would like to consider and list the characteristics that make it emergent ?

Two things. You never told us what you are growing in this soil. Conventional gardening wisdom is that since to are relying on in place soil microbes to do anything to the dust, you will lower the nitrogen levels of the soil whilst they perform this task for you. In the long run it may improve the soil, but that will take more than a year and by then you will have more leaves.

confused or not listening ? I'm done with this thread.

You have asked this question in the relativity section, so you should expect answers pertinent to relativity. Objects in relativity theory do not travel two different paths at the same time. I was deliberately brief on quantum superposition as it has some quite different characteristics from classical superposition. I suggest you forget mixing the two. I have litrally dozens of textbooks describing superposition in electrical engineering, structural engineering, civil engineering, and several other disciplines. The technique goes back to the catapault where two pieces of elastic are used in superposition to fire a projectile.

Not if the blocvking object was big enough. There is a strong link between emergence, complexity and catastrophe theory. You should read up on Rene Thom https://mathshistory.st-andrews.ac.uk/TimesObituaries/Thom.html

That is why I said I don't know. We are in the best guess situation for life. And yours is as good as mine. Well I don't know of any charged particles that have no mass, so take your pick. A further thought about 3 particles and Markus Hanke's definition. An eclipse is a particular phenomenon concerning one particle blocking the light of the second from being received by the third. But this only occurs momentarily in a particular configuration. Can this be considered emergent ?

IMHO it has occupied far to large a % of the Physics curriculum for several decades now.

Neither of the particle pairs are entangled in my gravity or electrostatic examples. Ther is only one line between their centres and the relationship obeys the inverse square law along that. The PE is found by considering the work done in bringing one of the particles from infinity to its distance from the other one. "Can you say that?" Why not ? We don't know what sequence of events lead to life, but would life occur every time ? There have certainly been attempts to mix molecules thought to have mixed at random and they equally certainly haven't resulted in life.

Thank you for reading my long post. I tried to make it short but needed to get a lot in. Life - I don't know. Good question. One thing about life as an emergent phenomenon is that Physics expects reproducability. So every time you perform a particular procedure you get the same result. Is that an essential characteristic of emergence ? All my examples have this characteristic, but life doesn't. Not not less than 3, less than 2, ie a single component. Take electric charge or gravity. A single mass or a single charge has no potential energy. PE only arises (emerges) when you introduce a second mass or charge called a test mass or a test charge. But there is very little configuration you can do with only two participants.

Magic ? You 'started' this thead by introducing a difficult to define concept. Please don't introduce another one. I am glad to see folks working together in this knotty question here are some of my thoughts. Althought the thread is specifically aimed at Physics it is worth noting the meaning of emergence in other sciences and comparing. Also the age old technique of taking simple examples and seeing how they stack up against proposed definitions is valuable. So. 1) Emergence has long (centuries) been used to describe radical change or transformation in the biological sciences. For example the emergence of a butterfly from the pupa. Characteristics are that you cannot have a butterfly without a pupa, but once you have a butterfly you no longer have a pupa. The change is not reversible. You cannot resolve a butterfly into a pupa as you can with sinusoidal functions in my third example below. Note this example does not conform to Joigus' definition (which I like) so that definition is is not complete. OK back to applied maths (sorry physics) 2) 1+1 = 2, 3+5 = 8 in fact take any two or even lots of numbers and add themtogether and you will get another number. That is the result is contained within the set of all numbers. You do not move outside the set. But add all numbers in that set and you get infinity, which is not a number. So you have something that is not in the set ie outside the set. This example does conform to Joigus and the relationship is the additive property of individual numbers. 3) A more complicated example comes from the set of all continuous functions - commonly called C∞ - All sinusoids belong to this category. Like with the numbers above, adding any two or a large number get you another member of the set C∞. But adding an infinite number can get you you a function that is not continuous ie is discontinuous, notably a square wave. So once again takes you outside the set. Scary. 4) I potential energy an emergent phenomenon ? Particles, by themselves, do not possess PE. By configure two or a bunch of them and they suddenly possess PE by virtue of their configuration and their interaction relationship. The number of configured particles for this example of emergence does not have to be infinite. Indeed we can only determine what happens in some specific cases if they are infinite in number. 5) Take a pile of bricks. In most configurations the pile is unstable. But configure them into an arch and the configuration becomes very strong and stable. Again only finite number of participants is necessary. But in this case we also have extremal principles to apply.

Fair comment, people in different climates garden differently.

Have pity. A meteorologist is a guy who can look into a girl's eyes and tell whether.

I haven't missed any point. I have tried to make the point that hydroponics has little or nothing to do with the use of rotting leaves and other vegetable matter., which this thread is about. I am sorry if that was not clear but I see that Seth has explained it better himself. You are however correct in that the late 20th century has brought in a new technology to do with this in tthe guise of biodigestors. The spread of these has been accelerated by the push for recycling. Also a candidate for newer technology would be the making of silage. Although this is to do with stems as much as leaves. I wonder if my use of the words compost and rotting are causing confusion. Leaves will eventually rot whether you compost them or not. Your mention of 'milling' makes me wonder if you are referring to the used of machine shredders ? Certainly many gardeners use these to create a finer consistency of the materials, which can include stems and twigs and bark. This produces a finer more even consistency material for 'mulching'. The main purpose of mulching is weed suppression and moisture retention, not fertiliser although the shredded material (pulverized ?) eventually rots down to return any nutrients to the soil. Equally this process accelerates the rotting. So I don't see how you can divorce the two.

This question deserves a thread all to itself. I think any definition of emergent v fundamantal has the inherent problem/danger of becoming self referential. This is because before (in time) anything can emerge the 'more fundamental' thing must already exist. So how does the time bit of spacetime fit in ?

OK the definition of superposition is largely correct but rather akward to work with and not totally correct. In particular the physical phenomena do not have to be of the same type and the examples given could be difficul to apply without further informatuon. Two or more causative or controlling agents act on the same body or in the same region of space or in the same electrical circuit they are siad to be in superposition. a) So two voltage sources, one alternating and one direct, acting on the same electrical resistor are in electrical superposition. b) Gravity and the thrust from a rocket engine are in mechanical superposition. c) Two waves acting along a single string produce a combined wave by acting in superposition. An orchestra has many instuments acting in superposition to produce music in the concert hall. These are examples of classical superposition. d) Two quantum wavefunctions acting in the same space are may be in quantum superposition or they may not be depending upon circumstances. Examples a and b are what are called linear superposition. This is good because you can simply add up the effects of each acting alone. Example c may be linear or non-linear. You cannot simply add the wavelengths as suggested by your dictionary. So back to your question. Yes there is a region of space, but there are no causative agents acting. An observation, calculation, measurement or reckoning is not a causative agent. I said reckoning because direct observation or direct measurement of relativistic effects are generally not possible. The effects have to be deduced from indirect measurements (called observables) The two moving observers cannot directly observe the length they have to calculate or reckon it using the correct formulae for the frame concerned. Of course relativity also says that a third observer located in the frame of the two points, frame 1 cannot directly observe what the other two observers see. Does this help ?

Thank you, it's good to have a rational discussion with someone.

Actually there are three different reckonings to the distance between the two particles. One corresponding to each of the three frames I listed. Why do you think I said reckonings not observations or measurements ? And why do you not cooperate by answering my questions ? I am trying to find out what you understand superposition to be, so that I can help you simply. Because it is not. Because the situation you describe does not conform to the standard definition of superposition. But I am not going to go through another 5 pages of argument with you about a definition which is not mine or yours to make.

The short answer to the headline question is no. I don't know what you understand by superposition - perhaps you'd like to tell us. Quite simply there are three frames involved in your scenario. 1) The frame of the two particles. Because they are in the same frame they must be at rest with respect to each other. 2) The frame of observer1 3) The frame of observer2 If frames 2 and 3 have different velocities relative to frame 1 then they will reckon the distance between the particles as being different.

But then it wouldn't all be waste heat would it ?

Thanks for this. +1 As regards checking, might it not be prudent to simply persuade a bunch of folks who have tested omicron positive with a pcr or a spit test to take a lateral flow in the interests of society?

I can't remember whether it was epside 8, 9 or 10 where they stated exactly this in so many words. "...the only life possible outside Earth would be an artificial intelligence." I am trying not to spoil the series for those who might wish to watch as it was really quite good and explored many issues in a way that only SF can. Some ideas were drawn from 'A space oddesy' - but were , in my opinion, much better done. I think oddesy was much overrated.

Do you know of any solid evidence (yet) that confirms whether or not a lateral flow test does detect the new omicron variant ? That is does it produce a positive result even if it doesn't distinguish variants?

The episodes are only 25 minutes long. The BBC has two series of 10 episodes each. So far I have only watched the first series.