studiot

Welcome gobin, you may consider yourself anovice, but you seem a well informed one. Normally resurrecting such an ancient thread, rather than starting your own new one, would be inappropriate but I can see how your post follows on from the discussion. Classifying chemical bonds as inter (between) or intra (within) molecules only makes sense when molecules as indivisuals are actually present. More advanced authors, such as Cotton and Wilkinson, use the word aggregate, not molecule, to describe ionic bonding in solids. Other authors use words like lattice, crystal etc. So perhaps you would clarify what exactly did you wish to discuss, bearing in mind that science has developed the 'term' molecule considerably since Descartes first introduced the word in the middle 1600s. Indeed some technical disciplines have extended it further from being a definite physical or concrete noun into purely abstract concepts.

Well, as I said, I disagree, though it is a fine linguistic point. The correct tense to use would be past not present. However we all seem agreed that there are plenty of different possibilities.

+1 Yup I must own up to asking for one or two particularly stupid bobos to be put right that way, in case a later reader only read the first post and not my later apology and correction.

As I see it there are several possibilities not considered, either in the question or in the answer. My (correct) answer is: Since A's mother has not been declared alive, no one is a possible answer if A's mother is now deceased.

A couple of brief comments about constants. Firstly there are not as many independent constants as some in this thread seem to think. (Welcome back genady ) The SI scientific system which defines all scientific measurements, is based on 7 base quantities and 7 universal constants So sure there are lots of more convenient constant and quantities for all and sundry, but they can all be related back to these 7 + 7. Secondly I would put it more strongly than Markus +1 I have always understood that astronomers knew that the further away we observed, the further back in time the light we observe came from. As a result they have spent decades seeking changes to spectroscopic observations that could only be explained by changes to these constants in an earlier age. As far as i know, no such changes have ever been observed. That is a major task of the Hubble, James Webb and SKA telescopes. SKA: https://www.bbc.co.uk/news/science-environment-63836496 Thirdly I agee with MigL +1 This should have been established on page 1 of this thread.

I agree so I asked Arnie. He said "watch my films, the car press wins every time."

Hello, erik, I see you have a total of 15 posts resulting in 4 plus points since you joined. That's better than 1 to 4 and better even than our most senior moderator. Please don't feel threatened, you are doing exceedingly well.

I'm glad to see the biology experts are back with us so perhaps they might explain something I have oftern wondered about please. Humans clearly have some capacity to regenerate, as witnessed by the fact that we grow and then discard one set of teeth, before regrowing a second set as we become larger. Presumably there is some genetic coding that controls and enables this ? Has any research been done to try to extend this capacity more generally to other body parts or even athird set of teeth later in life now we are living longer ? What are your thoughts ?

Please read again more carefully and more slowly what I wrote before. What connections do you mean ?

Most electronic circuits are pretty dust and dirt proof by nature. The main threat to these circuits is that they attract dust and dirt and that dust and dirt will coat the circuit board, components etc with a layer of dirt that sticks. This layer then thermally insulates the board and components and may cause some of them to overheat and fail. Most circuit boards can also be taken out and scrubbed in mild soapy water (or scrubbed in situ). So long as the assembly is thoroughly dried out before power is again applied everything will be OK.

Hey Mordred, it's good to see you back. Hope you made your fortune during you long(ish) abscence. I can still see you maths, they haven't disappeared. But the forum layout has been updated so rolls up a longer post with "expand" at the bottom.

I see no support for this outrageous diversion. Can we get back to Covid, which is a serious matter ? I learned today that the UK NHS has run out of Remdesivir, the only treatment drug if you have serious covid. What is more the medicines department at our district hospital cannot get more, even though they still have closed no-go areas dedicated to serious covid patients. The covid pandemic is far from over and there is still plenty of time to get properly vaccinated. At least that is still available.

Thanks for the heads up. Glad we have some alert mods here. Pity though, as real new members should always be welcomed.

Thanks for quote Eise. +1 [aside] Perhaps we will see you in the next round but one. [/aside]

Here is a most interesting applied maths (fear not you only need the four arithmetic functions to +,-, * ,/ to follow it) discussion which in cludes the answer to your question and may help with many of you other ones. https://risingentropy.com/matter-and-interaction-in-quantum-mechanics/

Whilst I can see this is not the best place to put an introductory post, I really can't see how it merits a negative rep point so I have balanced that out. William, welcome and start with a clean sheet. Well done for starting engineering college , I look forward to productive post from you, but please think about whare you place them.

Aren't these all provided for in 'the standard model' ? But how is this classical physics ?

There is no such thing as pure energy and the hot death of the universe is a self contradictory myth. I respectfully suggest you need to properly understand what these terms mean before you can understand entropy, which then really becomes very simple.

Nobody is mad at you, we are just trying to guide your thinking so you can see for yourself. 1) Black body radiation. I stick a poker in the fire and it glows red, then yellow, then white. I don't see any quantum interactions here and you have specifically limited this discussion to quantum matters. 1) Photoelectric effect Here there is an interaction because an electric current is produced when a light shines on certain materials. But there is nothing that suggests light needs to be a Field. Swansont mentioned one of the characteristics of this effect that lead to the conclusion that this must be a quantum effect since classical EM wave thoery will not produce this effect, but a different one that is not observed in practice. Read the attachment I previously posted before you reply. I don't think I have posted this analogy since you have joined but maybe it will help a bit. Think of a stream bed with an smooth clay or sandy bottom. The stream flows in steady parallel lines with no disturbances. This is an example of a Field, called a flow field. Now change the bed to a rocky bottom. The flow changes and eddies appear around some of the rocks. A few of these eddies are transient but many are persistent. These all constitutes a disturbance in the field and involve greater energy due to the rotation of the fluid field at the eddy location. Noone pretends that the eddies are points, they occupy real volume. So within the field there can bee seen persistent disturbances, of higher energy than the surrounding general field. These disturbances can be regarded as self contained entities, and if they relocate they move as self contained entities ie they have particle like characteristics This is a very simple picture of the proposition 'a particle is a disturbance in a field'. Does this help ?

Car batteries weigh somethng like 800 to 1500 lbs depending. Here is a list of some specs. https://motorandwheels.com/electric-car-batteries-weight/ However yous is a hiogher end battery so I would expect it to weigh in at the higher weigher, something north of 1000lbs. Particular manufacturer's wesites will tell you more specific information for their particular models.

Since I didn't see it before and I don't see it now, please enlighten me. Interaction of (what) with (what) ?

Thank you, but you also said a deal of other stuff, which is confusing as to your intentions. 1) I see neither a field nor a particle nor an interaction involved in black body radiation. 2) Not all fields are 'quantized. 3) Einstein's contribution was most definitely about the interaction, although as it takes two to tango, you can't simply concentrate on one or the other.

The short answer is "They don't" Actually that is not what Planck postulated, nor did he introduce the term quantum or quanta, that was Einstein a few years later. Rather than arguing back and for about it, here is the official Cambridge University history.

Please clarify the scope of this discussion. What do you mean by particles ? And is the discussion to be limited to particles as related to quantum mechanics ? The idea and knowledge of both waves and particles goes back several thousand years. Obviously these ideas have been extended and refined greatly over that period. In that time we have discovered phenomena that are best explained in terms of particles and also phenomena that are best explained in terms of waves and some phenomena that could be explained in terms of either. At first some aspect of each particular phenomenon allowed a distinction to be made. For instance the direction of deflection in refraction. But late in the 19th century phonema were discovered that fitted neither model (you haven't forgotten that both waves and particles are just models have you ?) completely and contradicted each model in some (different) way. QM was originally introduced as a way of reconciling phenomena that fitted this category. As many more such phenomena were discovered in the burgeoning scientific world qm grew in importance and value and developed to what it is today. A better model that describes more phenomena. But it is still only a model.

Sorry if the post was a bit rambling. What part was not clear?