studiot

Yes indeed. So explain to me the units on the two types of axes, or explain to me why there aren't two types of axes, or why we don't need units for them. Yes we still have x,y,z,t but remember that there is no absolute coordinate system. That one refers to that entity and that light cone. All measurements in xyzt are as observed by the entity at the apex of the cone. Any other entity will have her own cone with coordinate system x'y'z't' Roger Penrose didn't realise the confusion his beautiful diagram would cause. I still await the explanation of v

With respect, I thought you had picked up the point that we don't. Two independent sets of axes are required. Because as I said we require at least two entities for the comparison The 'transformation' in schneibster's post#158 refers to the mathematical link between them. I await his explanation of v

Michael123456, thank you posting a light cone pic. (post#139) But you have the basic deductive sequence back to front. We note (observe) that we cannot observe the future and posit the light cone explanation. Not the other way round. That is the scientific method. Schneibster, yes it is in the maths. So do you understand what you have posted? If so what is v?

Yes indeed, which is why I objected to the use of the word 'faster' in some earlier posts. There are quite a few instance of physical quantities that have been introduced to satisfy an observed need, Entropy is another. Unlike entropy for which the need is only apparent in sophisticated systems, the need for time is pretty immediately obvious in very simple ones. As you say we even have an innate 'sense' of time. However our perceptions also lead us astray when dealing with subtleties. Your description of drawing curves is a description of the parametric equations of a curve and in many maths books you will find the parameter called t, justified by the addended phrase "since t is often time".

You should be using the MKS system. Length is measured in metres, so bring all lengths to metres (and powers of 10) Force is measured in Newtons Mass is measured in kilograms density is measured in kg per cubic metre. So if your radius is in cm, and therefore your volume is cubic centimetres, your mass will be wrong, and thus your forces will be wrong. You can work in other units, but it is just so easy to make a mistake and get things 10, 100, 1000 times too big or small. That is why I said be consistent. Have we cured the negative sign now?

One of the most important lessons to learn in GCSE is to be consistent in your units. This is why it is recommended to always state them in full. Let us look at your figures. So do you have a 2.5 metre ball? you say the density of the ball is 0.35 whereas the density of the liquid is 1 and a bit. So why does the ball fall at all?

No you are definitely not stupid. If you use the more reply options (button towards bottom right) you will find a way of uploading files to your post. Click the cursor where you want it, after uploading, and it will be displayed there. g is regarded as constant for schoolwork, even at A level. It actually gets smaller and smaller the further from the centre of the Earth you get, so that has to be taken into account for rockets etc. It is normally taken as 9.81 Newtons per kilogram of mass. So a mass of 1kg weighs 9.81 Newtons force. (10 is often a good figure in rough calcs)

Good morning, Lizzie,L. I understand and support your point of view with the following proviso about change or movement. It is comparison, not change or movement, that is the key. Without comparison we cannot demonstrate change or lack of it. And it also follows that we must be considering at least two identifiable entities to compare. I have been trying to prompt those here who feel that they can offer an insight into time through relativity, the spactime continuum and sundry mathematics to explain why they are doing the manipulations they offer. I thought someone has posted about a light cone but I can't find it now so it must have been in another thread. Never mind. The point about light cones, Lorenz transformations, etc etc is not change or movement but comparison in mathematical terms. The equations diagrams etc follow a well worn scientific path that has served well for many purposes. That path is to consider relevent properties of a 'point particle' and scale up to many particles. Now for most purposes we can simple sum the effects of all individual particles so to obtain for instance the mass of a body as the sum of the masses of all the individual particles that make it up. There are, however, observable properties in this universe that do not sum in this way. They are different. When we write equations to link the connection between these particles, time is the parameter we use. Hence the why of the transformations. If we wish to compare physical properties of two or more particles, each with their own light cone, we need a mathematical connection that applies to both. I also tried to discuss the physical reality of, past, present and future but no one took this up. It is a simple exercise in logical observation to show that because we can "see into the past", given the present, that the past has as much physical reality as the present. Moving into your realm, it is a short stride to realise that I can remember a past time when my present was in my future so I can offer nearly as strong evidence for the existence of the future, although I cannot "see" it in the present.

I'm sorry I don't follow this. Who is the first party? At line 1, I thought that the first party was the proponent of A, the main claim. But then at line 3 you say that the first party says A is false. Why would the first party deny the truth of his own proposition?

g in the formula is the acceleration due to gravity. If you multiply the mass of an object by g you get the weight, which is the force of attraction between the Earth and the body. So the forces acting on the falling ball are the weight w=mg, the bouyancy force due to the displaced fluid and the viscous frictional drag against the motion. The mass of the ball obviously equals its volume times the density, and the mass of displaced fluid is similar, hence the subtracted quantities in brackets. It is difficult to help without knowing what you are expected to produce.

I missed this cool fact and would like to go back and highlight it because it's cool. It's the relation between a dimension and space dimensions that makes it a time dimension, not the character of the dimension itself. A dimension is just a dimension. It's its relations to the space dimensions that make it temporal or spatial (and if string theory is right there are some other states too). +1 for actually listening to someone else. It makes for a better quality discussion.

What did I say that in any way suggested I intended the above function to require or define a spacetime continuum? x is a general variable and x squared was an example function. If you prefer I can rewrite it as [math]\xi [/math][math] \to [/math][math]f(\xi )[/math] You are still missing the point that you cannot legitmately use time in the definition of time so properties like 'faster' are excluded because they require a definition of time to be able to make a speed comparison . As regards to spacetime, I did not ever refer to spacetime since the OP asked specifically about time. Your link offers the fundamental postulate of the existance of a spacetime continuum and then goes on to develop a number of properties. But It uses a further number of hidden assumptions (as does Euclid) and it is drawn in Euclidian geometry. Do you know what those assumptions are?

+1 a very perceptive statement. Especially when you consider the metric involved.

Forgive me for not understanding how a transformation of something is used to define that something. I always understood a transformation involved changing something into something else. So for instance how would the transformation [math]x \to {x^2}[/math] help me define x?

Judging from your excellent rendition of "Integration the Movie" here, perhaps you should read some popmath eg Penrose Tiles to Trapdoor Ciphers by the aforementioned Martin Gardner. or Another Fine Math You've got me Into by Ian Stewart Beware, however, there is a danger you might enjoy it.

Thanks, +1, I would remove both our entire posts if I could, since they are now redundant.

Strange, your post#92 incorrectly attributes a statement to myself.

As far as I know, Baez is not a member of this forum, and can't speak for himself. I am asking you to tell me what you mean not what Baez may or may not mean, and in particular to provide a definition/explanation/basic understanding of time as per the OP without reference to t or time. Unfortunately , your entire post#90 is a circular (pun intended) argument because of this. You just cannot use words (eg faster) that include time to define it.

Perhaps that's the difference between proving (or disproving) something and explaining something. If you set out to prove or disprove a statement then you need to present the necessary flow of logical argument in full, without appeal to ouside authority, however august. If you set out to explain something to someone (and I have seen you do this well several times at SF) then it is legitimate to say "this is the (standard) text on the subject, read section XXX" Incidentally there are many, many texts on relativity. Macomb, Dodson & Poston, The Manchester Physics series and even Griffiths spring to mind, although none are 'popsci'.

Have you ever read any of Martin Gardner's work, or that by my other reference? https://www.google.co.uk/#q=martin+gardner

Relativity. And there is no "proof." That's pretty good evidence though. Lizzie L, on 22 Feb 2014 - 3:49 PM, said: The spatial dimensions are right circular and the temporal dimension is hyperbolic. Here is the article on it, from John Baez: http://math.ucr.edu/...symmetries.html Here is the hyperbolic trig Lorentz transform: t → (cosh s)t + (sinh s)x x → (sinh s)t + (cosh s)x y → y z → z where, s, the "rapidity", is related to the ordinary velocity v by v = tanh s Well we seem to be getting somewhere in the second part of that post, since I can now see that you are talking about conic sections and their properties, when you use the word hyperbolic, not for instance, hyperbolic differential equations or other possible meanings of the word. So please spell out exactly what you do mean when you say Time is hyperbolic, space is circular.

Well perhaps it's just me but I can't see an attachement in your post.

???

It's difficlt to know what to say in a thread that has clearly wandered off topic from a discussion of the general provenance of sources of any form to the specific bashing of a particle genre of writing. I have been following this thread but so far only objected to some of the attitude of the OP, and it seems that several others have agreed with me. I agree with Ophiolite. There are many popsci writings that are far from trash. The writings of the late Martin Garden and the not so late Ian Stewart come to mind. Further surely the response to any input should be tailored to the level of sophistication of any discussion. We do not try to explain Joule's experiment to a 16 year old via Noether's theorem for good reason. So it follows that the level of any references should be commensurate with the level of the discussion.

+1 querulous I would start my list with the The Shorter Oxford.