studiot

Have you ever been taught how to provide a reference ? Or have you ever studied the subject of the science of measurement errors ? In particular do you understand the definitions of and differences between accuracy, precision, tolerance, limits and fits, significant figures, boundedness ? The last one is particularly relevent as Seth has quoted an inequality.

Very interesting about the vitamins, I had no idea, especially in a northern country that lacks the environment to grow the more tropical and subtropical produce. Many foods, including bread. are fortified by law in the UK. Noted Bear in mind yesterday's local elections where Farage seems to have done rather well.

I just noticed what to me is a new forum function, although it may be just that I never noticed it before. I have two screenshots of the summary function showing what I was offered at the top of a thread and what happened when I accepted the offer of a thread summary. Can someone explain how 'the most posts are selected' please ? I am not complaining about this function, just trying to understand it.

I would be interested to learn why you think this is so.

I'm glad there is something we can agree on. You keep referring to a stored version and similar concepts..... The universe is defined as everything there is. So where is this stored copy kept ? The only way I can see to make your model workwould be if the universe was actually like The Matrix (this time I am referring to the films). There is a problem with perception in that it can be tricked. Have you heard of Trompe L'Oeil for instance. All our senses can be fooled. That is why scientists strive for objectivity. Granting your little scheme to fool folks by changing the clocks could be achieved in a thought experiment, it would still fail becasueof external markers. For instance if I were to have my sleep by the seaside and be woken 2 hours early, with my watch advanced the extra 2 hours, I would immediately know this was wrong becasue of the incompatible state of the tide. I include information for you that I thought was relevant. If you don't even acknowledge it, this ceses to be a discussion.

What makes you think I haven't aready done that ?

But that didn't answer my question. FYI My family's association with the medical sector goes back generations. My daughter has a medical degree from Edinburgh and post graduate Pharmacy from Aberdeen. Her childhood friend who is the daughter of one of my wife's London University friends is now a consultant (if you know what that means) radiologist with the South london Hospitals group. (radiologists are in even shorter supply than radiographers). Of my daughter's medical friends one male is a consultant gynaecologist in Belfast, others have taken up various specialities. So, although not personally a medical professional I have long been very close to it.

You are posting a large number of statements and claims about certain aspects of Medicine. How much personal experience do you have of this? Or is this just stuff you are digging up to prolong the discussion?

Unfortunately you don't seem to understand what I am saying. You would not expect time and space to be exactly the same or there would be no point distinguishing between them. But They do share some common properties in our universe at least. One such property is that of continuity. Your model breaks that continuity, which is what I was trying to demonstrate with my train analogy. Most folks perfer and understand the train analogy more readily than taking cross sections. Perhaps your background would lead you to prefer that. Again Actually something like this already happens in reality. (what constitutes reality is a good subject for another discussion ). I mentioned the Terminator and tried to add a joke (mantion of Arnie was a joke but I can't get the joke emojis to work). It is the correct technical term for the dividing line between day and night which allegedly moves or seeps acroos the land (or around the globe). But of course actually the Terminator stays put and it is the the globe which revolves under it. Which brings me to another o0f your ideas. Have you heard of the block universe ? Because back along you only seem to accept that the present 'exists' (another word which needs clarification) so consider past, present and future and how they work. There are several possibilities. In the block universe they all coexist and time does not flow. Alternatively the present is some sort of terminator as a line between past and future and in your last post you seem to think that the past somehow disappears once the present has passed over it, just as the day dissapears when the terminator brings the night. Which brings us back to 'reality' . Night and day are abstract nouns but they and their difference have a dramatic effect on the material world. However as the terminator changes day into night it does not mean that New York dissapears, it is still there. Another common property of space and time is the behaviour of wavefronts. If you just write numbers along the space axis or the time axis the wave and wavefront appears indistinguishable (and continuous). Your description of a future which is not set is similar to a wavefront spreading out, but again from the source to the front is still there although the front has passed that region. So you need to consider all possibilities and choose one, giving your reasons for the choice. Then again you have not responded to my comment about the special meaning of the word event and coordinate systems which also has implications. As a final question can something which does not exist affect reality ?

There is no need to apologise, no one knows everything the main thing is that we learn when when encounter something we did not know before. The word event is specialised in spacetime theory as meaning a point in spacetime with specific coordinates (x,y,z,t) or (x, y, z ct) However nice as such a system is it actually contains redundant inappropriate information. Eddington explored this and also the consequences of multiple time axes. Both of these have consequences for any notion of time travel. Perhaps I am misunderstanding what you mean by individualistic ? Take a 1 metre ruler. It hast a beginning at 0 metres and an end at 1metre. In just the same way I am suggesting that I have a start point when I first arrive and a finish point when I die, in the time domain, allbeit that these points are a bit fuzzy. What I am suggesting is that just as you can't move the 0.5 metre point of the ruler to another location and still have a ruler, You can't move me aged 50 to another time and still have me.

Hey, guys I wouldn't have posted the link if I had though it was going to start a war.

I don't know who or what c. l. dean is or was, and don't really care as he is clearly not an ancient greek. This paradox is one of Zeno's and sounds rather clever. So clever that it took over 2 thousand years to resolve. Note a paradox is an apparent self contradiction, not an actual one. The secret of this lies in Cauchy sequences. Cauchy was the first to discover that the sum to infinity of a series or sequence can itself be finite and discuss the mathematics of this phenomenon. So the distance between each point diminishes as the divisions become finer and finer. So each division will take a shorter and shorter amount of time to traverse until zero time is reached for the 'last one' But it can be proved that the sum of all these times adds up to a finite total which happens to correspond to the distance = speed times time equation, just as all the inter division distances sum to the finite distance between the points. Note as a new member you have only one post left in your first 24 hours. Use it wisely.

Exactly +1 There was a recent health news BBC article about this subject. BBC NewsMale workers should be able to carry out mammograms, expe...The Society of Radiographers says allowing men to do mammograms would reduce staff shortages.

Firstly be aware that new members are allowed 5 posts only i9n their first 24 hours, for security reasons. So use your last post wisely, I don't think you are supporting your proposal very well as you are just reiterating what you have already said, although you are misusing some words which have a special meaning in Science in particular 'the fact that..' ; event ; I can't tell from this if you are agreeing or disagreeing with swansont but the onus is on you to support it. There are too many claims without support in your text and in particular it is not a fact that I as I did not say that, quite the reverse actually. SF stands for Science Forums not Science Fiction.

Reported Information should be presented on SF not elsewhere.

I agreed, but have you read the whole thread ? It has rambled far and wide. In particular my comment on definitions applies. The word Science has a range of definitions and it depends upon which one you choose.

The thing is that before you can talk about time travel you heve to define/explain exactly what you mran by 'time travel'. Consider railway trains. A railway train has a front and a back and, set aside relativity for the moment, a definite length in space. When referring to the train, space travel refers to the train as a whole, not to some individual carriage in the middle. We do not mean take a carriage out of the middle and replace it somewhere else on the track, leaving the rest of the train travelling along the track with a gap in the middle. So why should time travel refer to an object (living or not) in this way ? Why should time travel not refer to the entire duration of the object in time not just a chunk taken out of the middle somewhere ? No it is not a recording, anymore than the light and dark sides of a planet are a recording as the terminator (back in your box Arnie) passes over .

Trial aims to make airport operations sustainable https://www.bbc.co.uk/news/articles/cy9vwpqe5y8o

Had you read the rules you signed up to you would already know why your thread was moved to speculations. It was not dismissed at all. By way of explanation this site distinguishes carefully between mainstream Science and Hypotheses or Speculations. This is because it is also partly a teaching site and the owners do not want to put non tested hypotheses in with mainstream so ther should be no danger of the site disseminating inappropriate information. In order to do this the site has a speculations section, where there are some additional rules to place the onus clearly on the promoter of the hypothesis to support their proposals. I am telling you all this because it is a teasing suggestion and I look forward to you actually supporting it.

That's a new one to me. +1

First let me say welcome and +1 for encouragement at having the commonsense to create your post the way it is. I see that there are already several helpful replies as a result. Wow Griffiths. His introduction to books are university level, going into postgraduate. Anyway I am going to pontificate a bit then offer a couple of books that could be helpful (and obtained cheaply second hand) they are both accessible to someone who has a reasonable grasp of high school maths. This is not to say that maths is not necessary for Physics especially, but you simply need to be able to recognise what is going on, you do not need to solve maths that has taken many geniuses a century to develop it. So QM. Quantum mechanics is basically about energy and its relationship to other physical quantities. We are considering Physics so physical quantities. These may be material - ie matter or they may be non material ie fields, shadows and abstract quantities. Both material and non material quantities we deal with are every bit as 'real' as each other. There is an energy principle known as the principle of least energy which simply asserts that a system will seek, try or tend to achieve a state of least (or lowest) energy. This is what governs my interactions in Physics and leads us to QM. But we need to know what a 'system' is or means. A system may be an atom, an electron, a bag of potatoes, a pile of sand, the electric field surrounding an electric charge, or any part of the universe which we can isolate or separate by drawing an imaginary bokoundary around. I said atoms, and it was thought for a long time that atoms were the smallest posiible piece of matter which can combine to form molecules. We now know that atoms have a structure that is they are made up of smaller pieces, which in turn are made up of yet smaller pieces..... Anyway one of the successes of QM is to explain how and why atoms join together to form molecules and smaller pieces join together to form atoms. It is our (by now) old friend the principle of least energy. In fact this goes so far as to explain why there is such a physical quantity we call mass. I see that Eise has referred to 't Hooft - he had a big hand in that discovery. OK the books They are both by professors of Physics, well respected for their communication skills. The first is specifically QM, although Chad Orzel has also done one about relativity. The second covers a much wider area of modern physics and would stand you in good stead for an introduction to this. Go well in your studies

School Project ? This is homework. We don't offer a homework checking service.

Thank you that is useful. Perhaps your school can get hold of this book for you Chapter 5 is all about the BZ reaction., at high school science level. You probably know that simple oscillations can be represented by the simple harmonic motion equation Y = Asin(wt). There are many types of non simple oscillations which are still being studied and the terminology varies as they have wide ranging applications. The BZ reaction can display several of these including They are called quasi periodic oscillations, almost periodic oscillations, chaotic oscillations. The maths of these is beyond High School, however. You should be able to recognise the Brusellator equation, I mentioned before, as a differential equation but is to difficult for High School to solve so you will just have to accept Poincare's solution. Go well in you project and let us know how you get on.

Do the pictures represent the left hand rule and right hand rule ?

Perhaps it can be said that most scientists lean in an imaginary direction.