michel123456

My little girl was born exactly yesterday. I still feel her weight on my shoulder. I still measure her smaller than my forearm. Today she is 22 years old. She is taller than me.Time is very strange thing. Kiss and hug your baby as much as possible.

That is because the educational system is not only there to make you learn something but mainly to filtrate.

OK the speed of light is defined to be a constant. So i understand that when space is expanding, SOL remains a constant. But when space is expanding, what expands is the metric. So, in order for SOL to remain constant in the new metric, the metric of time must expand too (and not contract as a firstly assumed). Otherwise, SOL would not be a constant under space expansion. The other way round would be to consider that "our" metric is universally correct and unchanging, that photons always move at velocity c as measured by "our" metric, and that photons are not affected by the expansion of space. But is that acceptable?

That makes little sense to me. In which coordinates do one measure that "they move at the same speed"?

You have taken as granted that time is not expanding nor contracting. How do you know that for sure? How is it possible that C remains constant when space expands ? by which mechanism do the photons "know" that they have to "jump" more and more in order to keep their velocity constant?

Well then, if Spacetime is static and if space expands, it must mean that time contracts.

Is this expansion of space or expansion of spacetime?

Interestingly, there is no down vote in today's democracy. There used to be, called ostracism. As much as i know, in today's democracy there is only vote up and no vote. AND this forum is not democratic. I think it has been discussed in the past as well.

You adapt to a law. You adapt to a behaviour. What you learn in this case is the way to behave in a kind of system (like the Talibans). You don't learn knowledge, sometimes you have to forget what you knew in order to adapt. Yes, especially when people do not get any prestige for their contribution in "real" life.

I profoundly believe that some people are here only because of the rep system. They like to accumulate points. That must fulfill their ego. Some of them dare to invite people to vote up like politicians do: "vote for me, vote for me". It would be an interesting subject for a paper on forum psychology. Not to learn. To adapt.

Do you say that as we have evidence that the earth was spinning faster in the past it means that the Earth was smaller?

So as i was spending my time, i had a look at this blog debunking the idea that the large size of dinosaurs was caused by a weaker gravity. And i have a question: In the blog, we see the following diagram And lower in the blog the following statement at the end of "Blue plate tectonic special: (maybe it was intended to be "blue planet") (enhancing mine) Which statement raises my question: Since the overall MASS of the Earth remains the same, why would the Moon's orbit change at all? The phrase "If Earth’s gravity had doubled since the time of the sauropods, we would expect the opposite effect." looks dubious to me, because the doubling of gravity should be understood as "doubling of the effect of gravity at Earth's surface", not doubling of the overall gravity of the planet since the mass remains constant. I hope my question is clear.

The problem with time is that a sentence with "when it didn't exist" presupposes Time not only once but three times. "When" "It didn't" "Exist"

The thread is about scaling, not about the model of the universe. Anyway. To me, it means that when scaling at a standard rate is applied to a macroscopical object, this object is submitted to acceleration. It happens when using a pantograph. For those who don't know or want to remind how work a pantograph , here is a small 5' video I found. I hope it is clear that when you draw at scale, the overall time is t for making the drawing but the 2 paths are different. It means if the original path is made at constant speed then the reproduced path (the pencil) is accelerated (or decelerated).

I have my own pet theory on this. It goes like this: Our ears work all day long (even when asleep) because they are warning devices. They gather information about our environment, as predators but also as a prey. A most inconfortable situation is when you are in absolute silence, then you hear the sounds of your own body. So IMO music is a situation where the sounds of our environment are covered, as if there was no danger to care about (like when you whistle to give yourself some courage) which means that you can relax, and the sounds you get are coherent.maybe predictable.

That is correct. It is the second aspect os scaling: _The base point does not change position. _A point 1 metre away from the base point will be repositioned 3 metres away (in my example)==>the gap=2m _A point 2 metres away will end 6 metres away==>gap=4m _A point 3 metres will go 9 metres away==>gap=6m _A point 4 metres will go 12 metres away ==>gap=8m And so on. Now, if scaling is happening in time t=1sec you have a situation where 1. the base point has not moved (velocity=0) 2. some point has moved at radial velocity 2m/s 3. some other point has moved at v=4m/s 4. some other point has moved at v=6m/s 5. some other point has moved at v=8m/s That looks pretty much like acceleration.

Yes, the grid has been scaled. And the points on the grid aren't. But when the grid expands, there is a change in position. ------------------------ And as I said before (with the feeling I am talking to a wall) The same exact effect is obtained when you keep the grid as it is, and shrink the points. Exactly in the same way with relativity of motion where you cannot know who is moving and who is standing at rest, the same relative effect can arise from scaling.

But there is a change of position. When we observe galaxies receding from us, I suppose you cannot say that they do not change position. Simply this change of position is not the result of proper motion but caused by the expansion of space. Isn't that what the model says?

It is the 2nd time on this forum that discussion goes about scaling and I'd like to make some point. Before using CAD programs, I must admit that I had a different view about scaling. My ancient view was simple: if you take a regular macroscopic object, say cup or a glass, and think that you must scale it 3 times, well things are simple: you get something like a vase. So I remember my first steps in Autocad and I was really surprised that it was not so simple. First of all, one has to consider that all CAD programs are ultimately mathematicals. Secondly, these programs are terribly dumb: if you don't tell EVERYTHING to the program, the command does not execute. Here comes the "scale" command and the sequence of steps in order to perform the scaling of a cup in Autocad. 1. select objects. That's fine, the program must know what object you want to scale. 2. input the scale factor*. That's fine, the program will follow my wish. I input number 3. 3. Specify base point ?????? Why the hell does the program need a base point in order to perform a scaling? Well, the reason is that the base point will decide WHERE the result will appear. Because any scaling performs also a change in position of everything selected, except for the base point. The remark may come from Autocad, but it is a real effect. Some examples below fig.1 In fig.1, you have a situation where Carolina and Dean are standing in a room. Next figures will follow with some examples with scaling from different base points A, B, C, D . fig2. fig 2. shows a scaling 3 that has been operated with basepoint A. One can already see that Carolina and Dean have changed position. fig.3 fig 3. Scaling 3 has been done with center point B. Carolina and Dean are at another position. However the scale factor is the same as in fig.2 fig 4. fig 4. Scaling 3 has been done for Carolina from her center C, and for Dean from his center D. The result, with multiple base points, is a scramble. In fact these were 2 scalings represented in a single picture. However the scale factor is the same with fig.2 & 3. In other words, if you make the attempt to make a scaling with base point from each point of this image, you must make an infinite number of scalings, and the result will be a mess. It will not be a scaling of the original picture, it will ressemble fig 4 in much worse. That is one aspect of scaling. * I have reversed intentionaly the sequence of orders. In Autocad the sequence is 1.3.2.

That means either I or you do not understand what happens when scaling occurs. I will open a new thread about scaling.

Some time ago, we were nomad.

That is scaling. It works only if the "points" are mathematical points, with dimension zero. If the "points" are 3d objects, the objects are scaled as well and they do not observe any change, no volume increase. Or it is the other wayout, and you must consider that the 3d objects are shrinking: then yes they will observe a relative "volume increase" even if the volume remains the same. -------------- The standard explanation is that while space expands, 3d objects do not expand because they are gravitationaly bound. So it means that space has a powerful hand able to transport the 3D objects at their new location from scaling, but that same hand is too weak to provoke a scaling of the object itself. I cannot swallow that. What I could swallow is the following: Scaling does happen, we are scaled continuously, and because we are looking constantly into the past, what we are observing in the past has another scaling factor than the one we have today. That would make sense.

If my statement is correct, by which way do we observe "stuff" receding? Because observation is about "stuff", not about space. IOW we do not observe space expanding. What we do observe is stuff receding. How can you reconcile all of this?

I am sure there are studies about it. Thinking about uniforms of all sorts, suit included.

I agree that it is VERY misleading. You have explained why it is misleading. Now it remains to explain clearly what the expansion of space means. If a volume of space is simply a filled region, it means, as I naively understand, that when space expands there is a larger volume of space with more stuff inside it. Not that anything else happens.