michel123456

Here a new one:

 

 

There is a very long table top, going from A to B, we want to measure. We are standing at point A. We putted a laser at point B, and we will measure the time elapsed for the beam until it reaches us in order to calculate the length of the table.

At time zero, we are at point A, the laser emits a light beam from B. The light beam travels through space & time and reaches us 2 seconds later. We are now at point A' (same location in space, 2 seconds later), the edge of the table is at point B' (same location than B, 2 seconds later). What have we measured?

I guess the A' B diagonal.

Something we could say as "6*10^8meters and 2 seconds"

I don't understand why you're calling it a "space part" and a "time part." That is just needlessly confusing. It's a calculation of spatial distance, full stop. Yes, there is a difference between the observed location and the present location. So what?

 

Well, maybe (surely) I am the one confusing things. If you read again the thread from the beginning, you may notice I am not talking about moving objects. The difference is not due to different locations. It is due to the time light takes to travel. When I take examples as stars or distant objects, I understand it is confusing. But I am only examining objects that don't move in regard to each other. Like a cup of tea standing at the edge of a table 600.000 km long. I have to completely rethink my last diagram I guess, and change the presentation. Working on it. Waiting for further comments.

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discarding the precedent diagram

Is that the arrow I putted on the Y axis that makes the diagram flawed?

 

B' is in the past. I cannot change that.

The observation of B from A is confusing. in fact, a ray of light goes from B' to A. So the Arrow on the Y axis is wrong. O.K.? or is there anything else?

I don't give up easily, do I? Lol.

 

Michel sees a 'contradiction' in my little spheres. What purpose could it serve to consider three-dimensional spheres when one-dimensional 'strings' are so much closer to 'infinitely small'? Well, my answer would be ... there is no such thing as 'one-dimensional' objects in a three-dimensional universe. They are purely mathematical constructs.

QUOTE]

 

Yes, you are probably right. I was probably wrong. But I realized it after writing my post. Except for the point that we are not living in 3D universe, we are living in 4D universe. You forgot Time.

And when you say "there is no such thing as 'one-dimensional' objects(...)" what would you say for zero-dimensionnal object (a point)?

It is not clear to me if we understand each other.

My intention was to make clear that in each measurement of distance, there is a part of space, and there is a part of time.

In other words, in each measurement of distance, time is included.

Here below a simple diagram to explain what I mean. Taking only points A, B, and B'. A is the observation point, B is an object, and B' is the point where the object was 2 seconds ago.(the numbers are taken only for clear understanding).

Here we are:

 

 

The measured distance is AB'. The astronomer is aware of the phenomena, and makes a correction in order to estimate the AB distance, the correct one, where B is supposed to be at present time. No problem, no mistakes.

As far as I can understand, that means that, in the AB' measurement, there is a part of the "real distance", wich is the AS segment, and a "correction part" due to the time elapsed, that is the SB' segment. So we have a "space part" and a correction "time part". We can see on the diagram that the "space part" (distance AS) is much bigger than the "time part" (the SB' distance). And really, if you had to measure a closer object , like your cup of tea, you would see that the "space part" of the measured distance is huge, about 99,999999999%, and the "time part" would be negligible, about 0.000000001%, maybe less.

Please it is time to correct me if any mistakes, because there is a development.

I suspect reality to be relative. How can you dismiss this theory without knowing how we appear to the galaxies speeding away from us. If history has taught us anything, what we previously thought to be the logical assumption of what we would find whlie looking for answers was far from what we did find. We only think we know what we know because of our perspective.

 

Don't take me wrong. Surely reality is relative. I guess more relative than we can imagine. More relative than Relativity.

Haha.

Photons have no rest mass, but they have mass when moving. They cannot stand at rest, so "rest mass" for a photon is meaningless. So, because they cannot stand still, they do have mass, but no they don't. Very simple.

"Gravity bends space", so space has mass. Hum.???? wrong. Sorry.

Have you ever made a Mass/Speed diagram ? Mass increases with speed. But speed is frame-dependent. So Mass is frame-dependent too. Rubbish. No it is not. Oh come-on.

My point of vue is that ST is very (very) interesting. There are some conceptual problems that make this Theory difficult to spread. But I think those can be managed.

For example, Pykawit is proposing spheres. Don't forget that we are talking about fundamental elements. How could be a fundamental element a sphere, a 3d construction ? There is a contradiction, IMO, what is the sphere made of? Some other, smaller elements? It is a never ending story.

The regular concept consists on finding a fundamental element (particle) that is like a geometrical point without dimension. Result of Democritos concept. String theorists make a step further, introducing fundamental elements of 1d, kind of geometrical segments. Objects that have one dimension in opposition with points that have no dimension. I think this step was inevitable from the moment we accept the concepts of quanta, the Planck length & the Planck time. Because those concepts are simply saying that null distance (a point) is physically meaningless. So that Democritos quest is ending somewhere before reaching a point. The surprising thing is that, instead of diminishing the number of dimensions in order to present only one dimension (a line), ST presents an increasing number of dimensions. That is quite bad. But I think that can be managed too. All the difficulty is in the definition of the word "dimension". All String theorists (not those on the beaches looking with binoculars: those in universities) are supposing that all extra dimensions must be spatial ones. These are the Calabi-Yau manifolds. What is a "dimension" really? I suspect there is a misunderstanding there. In my opinion, of course.

I hope we made an agreement, supposing that you have understood what I meant, and reversely, having understood what you meant.

 

So, the question remains: when you measure a distance, is the measurement you take upon the ABCD plane, or on the diagonal ?

It has been answered that "the distance doesn't involve time." And yes, of course, by definition, it is right. But what about the measurement of the distance?

I really don't know if the difference is clear. One thing is the distance as defined mathematically, the other is the measurement. Be careful that in science, measurement equals observational evidence.

Hum, pause.

You said

Everything I see is in the future.

 

No. Sorry for being abrupt. Everything I see is in the past. It may look weird but think about it twice.

Choose a target. You want to go to the Moon. Or to the kitchen. Look at the kitchen door, which is about 5 meters from you. The door you are looking at is some micro-seconds in the past because the image of the door needed some time to reach your eyes. For simplicity, let's say the door is 5 microseconds from you (in reality it is much less). You make one step in direction of the kitchen, and the door is now at 4 microseconds from you. Another step, the door is three microseconds from you, and so on, till you reach the door, at zero microseconds from you. O.K.?

The door that you saw, the target, is not in the future. You just made a construction in your mind putting this door as your target, a meeting point in the future. But the observed object was in the past.

Everything we observe belongs to the past. Nothing observable in the future. And, what is most astonishing, nothing observable in the present.

Hello-o. Is there anybody? I feel quite alone with my pencil. Do I have to ask a question in order to take some comment? (that was a question).

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Well, most probably, there is an error.

From the right beginning. From the first diagram.

Why that? It looks so simple. And it looks quite well to a simplified Minkowski diagram. What is wrong?

 

Look:

The vertical axis representing Time is the representation of the value of time (seconds). It is a representation used formally in mathematics to represent functions.

The horizontal axis is representing the projection of 3d space upon a line. It is geometrical representation.

To see the difference, you can for example put positive & negative sign upon the vertical axis, something you do upon a mathematical diagram. On the horizontal axis, you cannot do that. The left & right instance indicates a direction, not plus/minus. You can put for example East & West right & left.

Then you obtain a bizarre hybrid diagram.

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You would mock an original story that 'could' potentially, hypothetically, SOMEDAY replace the 'Star Trek', and 'Star Wars' franchises?

 

You'll have to rewrite your script so it fits in a few days or years.

So part of the formula had this factor a(t) multiplying it.

 

Silly question: what is its value?

 

..............

Wait a moment. Are you saying that this a(t) factor can be interpretated as acting upon time? Instead acting upon space?

The "at rest" situation is the most bizarre. All you physics books, from the right beginning, are interested in motion. When you ask someone what happens at rest, he will answer you that to be at rest or to be in motion is just a matter of Frame Of Reference. So, instead of postulating that A is moving, I can postulate that A is at rest. In this case, I know what FOR to choose, it is the FOR of point A itself. Examining what happens in this specific situation (a examing himself), we can see that "something" is happening. That "something" is what we call "time". And if we exclude all the metaphysical and philosophical blah blah, we can see that the situation of being "at rest" is simply a translation in time. Exactly similar to motion. Except that in this case, it is not motion in space, but "motion in time", a concept that has IMO no specific name in physics.

 

Wow, that was a long disgression.

You are in Galileo's workshop, with Isaac and Albert. What an opportunity. Let's see what they are discussing. They are examining Galileo's balls. Spheres. He has fabricated three spheres of exactly same radius, but of different mass. The one is in wood, the second in bronze, the third in polypropylene. You are presenting the above diagram you borrowed from this forum, and ask Galileo to represent one of his sphere. The greatest mind of all times (Galileo), draws the following diagram:

 

fig.01

 

Isaac ,the greatest mind of all times, takes a look and understand immediately that Galileo is not used to this kind of representation. He says, sorry Master, I think I can make some improvement to this representation. The sphere you know as a 3 dimensionnal object cannot simply be drawn this way, because the 3d space has been reduced to a single line. So the entire volume of the sphere must be reduced to a segment. And, as I have shown in my Theory (have you read it?) the entire mass of the sphere can be represented as if it where concentrated into its center of mass. As a matter of consequence, the sphere must be represented as follows:

fig.02

 

Albert, the greatest mind of all times, takes a look at Isaac's drawing. Well, this is surely an improvement, my dear Isaac, but you forgot Time. In my Theory (have you read it?) nothing can travel faster than C. In order to be accurate, independently of the size of the sphere, be it a small wooden sphere in a laboratory, or a huge planet, the principle is the same. In regard with an observator standing at point A of the diagram, the existence of the sphere takes place both in space & in time, because time & space are a continuum. So that the sphere should be represented extending in the past as follows:

fig.03

 

Galileo is surprised, but the greatest mind of all times understands everything. Something bothers him.

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To be continued.

If B' is the cup of tea sitting on my desk the length of time it takes the light bouncing off of it to reach my eye is going to be very short so the diagonal position will nearly be the straight line position, so the cup may as well be sitting where it appears to be.

Exactly.

If it is a star, well given what you have stated so far, knowing B' is only an apparent position I can only accept that the diagonal is an inaccurate measure of position.

Yes & no. Yes it is inaccurate in the sense that the star is not where it appears to be, as you said, see my comment below. And No, because we can make quite accurate mesurement of distance to the star as we observe it at point B'.

The star is not where it appears to be, so when I try to determine where it actually is, I can start by saying it is not there.

Yes. But in the verb "is" you mean "is at present time".It looks self evident, but it is not. In fact, what happens is that the star was at point B' (belonging to the past), and at present time, the star is somewhere else.

Then try to figure out where B is based on where A and B' is.

A is yourself, the observator, it is the point of your own FOR. The measurement AB' is valuable only for you.

If I figure out where B is,

In order to figure out where B is, you have to apply a projection of your measurement upon the ABCD plane. Projection means geometry, and for each geometry, for each Theory, you will obtain a different position of B, and a different AB distance. According to the Standard Model , the projection is not orthogonal, due to the expansion of the Universe. The AB distance is estimated as a multiple of the AB' measurement.(about 6 times larger, if I recall well)

then point out where it is to a friend, there had better be something shiny there, or they are going to assume that my cup of tea does not actually contain tea. They may be right.

Sort of. All the above concerning the star position is exactly the same as concerning your cup of tea. There is no scaling in Relativity that changes the Theory in regard with dimension. The Theory is the same for big & for small: a reason why there is no common understanding with Quantum Mechanics.

The fact that there is no scaling in Relativity makes me think that what is true for a star must be true for a cup of tea as well. In other words, as I mentionned before, when you measure the distance from yourself to your cup of tea, even with a solid iron stick, the measured distance is always the AB' diagonal. But I may be wrong on this. Some interaction with other forum members should be good here.

I admire your cold blood.

"Creation Museum"???????

From the Museum' web entry page:

"Welcome and Prepare to Believe

The state-of-the-art 70,000 square foot museum brings the pages of the Bible to life, casting its characters and animals in dynamic form and placing them in familiar settings. Adam and Eve live in the Garden of Eden. Children play and dinosaurs roam near Eden’s Rivers. The serpent coils cunningly in the Tree of the Knowledge of Good and Evil. Majestic murals, great masterpieces brimming with pulsating colors and details, provide a backdrop for many of the settings."

Is this a joke?

I thought I had to protect myself from such elucubrations coming from the East, I couldn't figure I had to care for the West too.

There are 2 meanings.

1.First go back to the first diagram, This kind of diagram you will find in any school book about the difference between distance & displacement. This is such a basic I don't want to go futher in. See for example here:http://physics.info/displacement/

 

You will observe that the concept of Time is absent. For an object travelling upon the path ABCD, distance is a certain amount of space (measured in meters or feet) and displacement is null. But once you introduce the time axis, you realize that some "displacement" has been taken place. This is not a regular displacement, because the word "displacement" we learn at school means displacement "in space". The new "displacement" takes place in time, and should be called otherwise, to eliminate any ambiguity. So in other words, all the above has been set up only to show what happens when the concept of time is introduced.

 

2.About my last question concerning the distance from a star. Take the second diagram & eliminate everything.Except point A, point B, and point B'.

If B is a star, the only way you have to measure its distance from you is through its EM radiation that is subjected to the restrictions of Speed Of Light. The star in point B, is not observed at point B, but at point B'. And the distance measured is of course the AB' distance. There is no doubt about it, and anyone having some basic information in astronomy will explain that better than I do. The question was meant only to introduce a doubt and make people think. Point B' may not be a star, the diagram has no scale. It may be the cup of tea upon your desk. And in this case too, the distance measured is also the diagonal AB'. It is always the diagonal AB' ,if you accept the cornerstone of Relativity i.e. that C is absolute & nothing can travel faster than C. In this case, if I am right, the measured distance is never the AB distance. But I may be wrong.

I found one recently that involved the metabolism of puffer fish in relation to TTX. I am not adept in the language it was written in, so I could not read it.

 

What language?

 

Most of the times you are just scr...

Large embassies have translations departments, some have scientific department. But it is a painful procedure.

Sometimes, the author of the paper has already made a translation in english. Go to the source & try to reach him. Russians may answer, and Chinese. German & French are usually too proud to go into such an humiliation (translating).

I can't argue with anything you said. We have reached a 100% agreement.

Now, if B' were a star, and if we were standing at point A....

The ray of light coming from B' travels at SOL, both in time & space, along the red line. I suppose you agree.

Where is the distance? Or in other words, measuring the redshift of B', are we measuring a distance upon the red trajectory, or its projection upon the ABCD plane?

Martin, my photo has been taken today with a VLT focusing on a point 41 LY from us. No kidding, on the picture I am about 8 years old. Today I am 49. I am architect, no physicist, quite far from my standard occupation. I won't tell you the story of my life. Some other time maybe. I like your posts because they are quite (not nervous), coherent and full of content.

 

Back to the point. I didn't expect anything of what you said. I was waiting for something like the Scale Factor. Correct me, but the expansion of space is often mentionned as a "scale factor", which is a very weird and difficult concept for common people. The scale factor is this instance related to "increasing-distance-due-to-the-expansion-of-space-without-motion". I have to admit I have lost exactly the point I wanted to raise. My mind goes at speed near to C and my typing like a snail. There is so much to say. I think that this search for immobility is wrong. Also I think that Newton was more relativist than Einstein, and if Isaac was still there, he would laugh at us. Also I am sure that something is wrong at the basis of our understanding of physics. Not being a physicist, I am "Out of the dance" (as we say in Greek), so I can throw ideas freely. Ridicule does not reach me.

Ah, I am Belgian french-speaking, I live & work in Greece now than 25 years. I speak & write fluent Greek language. I have 2 eyes, a mouth, etc. I like beer (belgian beer of course). Genealogically speaking, I am your cousin. And I can follow what you wrote about CMB.

Here is a new Universe for thinking about in 2010. Wishing everybody all the best.

We begin with a simple diagram (i love that):

fig.01

 

We are living in Space at Present Time: the red spot in the center.

the universe is there around us. Where is it? We know that all that we can observe belong to the Past.We cannot observe events from the future, and Relativity says that we cannot see anything from the present either, because information is always transmitted at speed max=C. So here is the Observable Universe:

 

fig.02

 

Great. But, wait a moment: The Universe, by definition, must belong to Present Space, isn't it? So, the "real" present Universe must be as indicated in the following diagram:

 

fig.03

 

As if the "real" Universe was standing perfectly at rest in present time. A screenshot of the Universe. A solid block in which nothing can happen, like a piece of wood.

The Pencil Universe:

fig.03

 

And what we are observing of this Universe, is a broken pencil. Like this:

 

 

Now, imagine yourself looking at yourself, there exactly where you stand, what do you expect to see? A broken piece of the universe.

Hello all.

I have noticed a surprising behaviour of time in the Forum. I mean time as it s mentionned near each post, & as it is mentionned at the bottom of each page.

 

Here times are GMT-7.

when I open some other page, it is GMT+2, which I prefer.

 

It is quite disturbing. What is happening?

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Sorry, I had to write it down to figure it.

 

When I log-in, time commutes to time of my PC.

Now you know my time zone.

Sorry for disturbing.

But it remains a strange behaviour.

Michel.

I suspect reality to be more refined.

In General Relativity, there is no substance called space.

The subsequent discussion assumes we are in the context of Gen Rel.

 

I can't keep putting the words "in Gen Rel" into each sentence.

 

So please keep the context in mind, as a qualification.

 

No absolute claim has been made that "there is no substance called space. What I'm saying is that in the mathematical framework we use in describing the universe, there is no substance called space.

There is no mathematical entity in the theory that expands----there are distances, describing geometry. And of course there is matter.

 

So when people popularize---when they talk about the current models of the universe in layman terms---they actually give a distorted impression when they say "expanding space" as if it were a substance.

 

THERE ACTUALLY COULD BE SUCH A SUBSTANCE, like an "ether". But there is not such a thing in the theory. Therefore it is a miscommunication.

 

 

 

Sorry if I wasn't clear enough. I was not claiming an absolute certainty that there is no substance that expands. Such a thing might be discovered one day. But in Gen Rel, the basic math model we use in cosmology to describe and predict, to organize and fit data, there is no such substance. And popularizers mislead people if they speak as if there were.

 

Intentionally or not, you were giving scientists a bad rap, in the sentence I quoted. Or scientists, or just me. Whoever the suspicion was being directed at.

 

A lot of people (not necessarily yourself) seem to have an anti-science bias. And they tend systematically to mis-state what scientists are trying to say, to make the message look doctrinaire, and cast doubt on its credibility.

This is a kind of straw-man debating technique where one misrepresents what another person is saying in order to discredit it. When this sort of thing happens to me, I reflect that it is often my own fault for not being clear enough.

 

Other times I think the main fault is with popularizers. There are scores of them, although the only names I can think of at the moment are Stephen Hawking and Brian Greene. They are doubtless not the worst.

 

What you said before did not involve a nozzle. You said

 

 

 

Now you imagine a surrounding vacuum chamber a 100ft cube

So a little box with 100 molecules sits inside the big cubical vacuum chamber. Somehow, in the twinkle of an eye, you instantaneously "remove the walls of the the box" as you said.

Now the atoms have more freedom to roam about.

 

I told you I thought there would be no change in velocity. In other words no change in the temperature of the gas.

The random thermal motion just has a larger scope.

 

However you are now asking about something different. You now want there to be a nozzle. A channel in which a pressure gradient is temporarily maintained and pressure converted into directed velocity.

 

I'm not sure how this is supposed to relate to galaxies. Maybe you should refine the image and try to make it relate to the universe in some way.

 

You should probably note that relative to the background, galaxies are nearly stationary. They have random motions which, when possible to measure, turn out to be a few hundred km/second at most. Whereas light goes about 300,000 km/second. That is, galaxies move on the order of 1/1000 of the speed of light.

 

However most of the galaxies which we can see with, say, the Hubble telescope, are receding from us at more than twice the speed of light. That is, the distances from us to them are increasing at over twice 300,000 km/second.

 

Recession is not the same as ordinary motion. It does not get you closer to anywhere. It has no destination. It is not limited by the Special Relativity Speed Limit. It is just a rate of distance increase.

 

A distant galaxy may give you the impression that it is moving and going somewhere. But it is not getting closer to anything. There is nothing ahead of it that it is getting closer to. It has no direction of motion. It is getting farther away from everything. It has no momentum associated with this change in geometric circumstance. Distances from it, as from us, can change at rates exceeding c. Because that change is not ordinary motion.

 

So somehow you want to relate this to gas in a box? It sounds like an analogy with very limited applicability. Useful as a visualization but not something that would make for a reasonable numerical comparison.

 

BTW Happy New Year! I hope we all learn some new things in 2010 and that the experience is on the whole pleasant.

 

Martin, this post of yours is wonderful. Your effort of explaining so many concepts in so few words is higlhy appreciable. It makes clear to anyone (I hope) how difficult are those concepts to explain, and to grasp. Talking about distances, for example, IMO there are 2 concepts-in-one. The first is distance in space, as we learn at school. Increasing distance is called motion, and increase of motion is called acceleration. O.K.

The second concept is "distance-out-of-space", a concept nobody learn at school. When geometry of space change, distance (the second concept) increases (or decreases) without motion. You must know that no layman can understand a thing of it. Please, use another word for the second concept, and maybe someone may grasp something of it. I have the very strong feeling that even very renowned scientists use the one concept for the other without taking any attention of it.