michel123456

Foul. To me (but that might be only me) in order for something to be, time must be there. Either time arises from the existence, or time is a necessity prior to existence, I don't know. But you cannot "be" out of time. You cannot "persist" in something that you want to cancel. It is a wrong concept. IMHO. To be more pragmatic and step out of pure philosophy, I have the feeling that in the frame of GR it should be possible to show that Time & Space are inseparable. That one cannot establish the concept of Space without Time. That the concept of 3D space "existing" or "persisting" without the concept of time intertwined to it does not represent anything close to anything. Interesting how we disagree. Please explain your concept.

I understand what you mean. Yes, your tea cup has different curves, and it happened that I didn't know why I should argue against your argument. It makes sense. The curve changes in relation with the spatial coordinates. No time involved.That seems OK But after more thinking when you are stating "when all the parts are present together", I suspect that you mean "all the parts are present together at the same time". Or maybe (I don't know to say otherwise) that your cup somehow is existing there in space "out of time". As if the concept of a cup "existing" could be understood without the concept o time. But the concept of "together" has already the idea of time inside it. When the bus hits you, it is because you shared the same space together at the same time. Because together at different times makes no sense. If you share the same space at different times, you are not "together". And after more profound thinking, in your statement, there is time 4 times: when all the parts are present together _when -are _present -together Good point. Maybe inside the concept "variable" there is also time hidden.

Test walking

You're welcome. I have to admit that I am quite surprised because the last time I suggested that time could inherently be inside mathematics I was hit by Zeus thunderbolt. IMHO what is described as a "change" is in fact a "difference". Another example: you walk in the desert an then enter the savanna, then the jungle. You can eventually say that the land changes (like the cup curvature) but what you are describing is not a "change in the environment", what you are describing is yourself traveling.

I my mind for change to appear you need a before/after relation. In the spatial tea cup example, how do you change spatial coordinates? Or how do you hover over the cup in order to notice the curve change? You can even say that the cup cannot have been created, it was always there. It is a mathematical cup-universe in which nothing can happen. I have even the gut feeling that mathematics have inherently time inside it. How can you make any calculation without time?

But can you have change without time?

In this case, how do you explain space expansion & time dilation?

Time is a constituent element of Spacetime. The world we live in is (at least) 4D. Geometrically, you can imagine a moving marble cube. It is a 4D object. If you take it to halt, it is still a 4D object because for some other observer it may be moving, and there is no preferred observer. For the other observer it is a cube traveling in spacetime. For you it is a still standing cube: a cube at halt is "traveling in time". An orthogonal projection of this cube on a surface reduces it as a 3D object (2D spatially+1D temporal) An orthogonal projection of the surface makes it a line, which is a 2D object (1D spatially+1D temporal) An orthogonal projection of the line makes it a point , which is a 1D object (zero spatially, 1D temporal) And you just found what time is: it is a geometrical point that "travels in time". It corresponds to the vertical line of a spacetime diagram. Which seems maybe not very much helpful. It only shows that in order to draw a point on a sheet of paper, you need time first. Without time you can't even think of standard geometry. The concept that we may have of a 3D space somehow "existing" independently of time is wrong. You cannot construct some kind of 3D geometry and then add time in order to "turn the engine on" and create change. It is conceptually wrong. Time was there at the beginning prior to anything else.

So why is it so difficult to answer the OP's question?

So that puts us back to square zero.

IMHO it is an error, they should care. Beginning with something simpler: Is space "real"?

And here another star vanished: (the headline of the article is funnily close to the title of this thread) https://astronomynow.com/2020/07/02/now-you-see-it-now-you-dont-a-massive-star-disappears/

That is out of my knowledge. The only thing I can say is that trying to change the elements (river, sea, land) in a specific way most of the times drive to unexpected results. I have the experience where a hotel constructed a small dock in the sea for his single inflated boat sportcraft had the result to erase completely its sandy beach.

Maybe, but as stated above your pictures are not showing. Ans some more explanation maybe? What do you mean with "wash away"? transformed in open sea, or transformed in agriculture? or what else?

There is no cosmological principle in archaeology, AFAIK There again, according to your reasoning, we must consider ourselves as the lucky ones that have access to all the information while the other observers in the far future will not have that chance. Doesn't that ring a bell to you? Do you accept that idea without an inch of scepticism?

1. No, he will not see the same thing as we do now. But he would know about the BB. So no problem to me. 2. Good question: he would live in a universe without the BB. He would not get any information about the BB. He may suspect that his galaxy has been created woof just like that by some kind of magic, or that his galaxy was always there & will remain forever. Anyway he would have no clue about the BB & thus should base his physics on some other Theory. So that is a problem to me. Please explain. They will live in a world without CMB

Even if these observers infer different physics?

That means it will be unfair for everybody. But that is related. If you believe in Universal Now or not. One must be consistent: if you are refuting Universal Now you cannot invoke it for another explanation. You cannot cherry picking explanations that contradict the other in order to explain the universe. And i am glad that you feel uncomfortable about it.

Oh. Does that mean that the entire Universe is now? Indeed the whenever has been introduced by me. It does not bother me that the universe is changing, expanding, faster. it bothers me when the Theory predicts a silly situation where the universe becomes incomprehensible. Imagine yourself as an observer in this future krauss galaxy. You are observing the sky and no trace of the BB. You are discussing with another guy and ask him if accepts the BB Theory. The other guy answers: What are you talking about? (He knows nothing about the BB Theory because he is observing a single Galaxy inside a huge void.) Isn't that complete bogus? Similarly, if this situation is possible, why would I accept that the universe is playing fair with me today? Why would I accept the cosmological principle today if it does not count tomorrow?

Read again the cosmological principle: from wiki The "is playing fair with scientists" part is the reason of the title of this thread. Following Krauss argument, in accordance to todays paradigm, in the future the universe will not "play fair". It will show a single galaxy in a huge void with no evidence at all for the existence of billion galaxies or the BB. Something does not sound good here. If the part of the universe which we can see is a fair sample, then the dinosaurs should have taken the same conclusion. And a future astronomer will make the same strong philosophical statement. If our model of the universe does not allow to some observer to make this statement, then most probably our model is wrong.

Well, the paradigm states that we are not close to the beginning: the BB supposedly happened 13,8 BY ago. And as far as I know, not any one of existing Theories about the fate of the universe states that the time Now is close to its end. In this case you must disagree with the cosmological principle. The dinosaurs were living on the other side of the galaxy, in another location & another time & thus witnessed a different universe because the universe is changing. The only one who is observing the same universe than we do is some E.T. on another planet somewhere else in the universe, right Now. But Universal Now does not exist. Or am I wrong?

Against anthropocentrism. The current paradigm is that we the humans are the lucky ones in the middle of the time line of the universe. To me it is highly unlikely. We know that we are not in the center of the Universe: our position is totally random. We are "lost in space". But we (you) believe that we are in a central position in time. I disagree. My opinion is that we should consider space & time in exactly the same way: we are lost in space & we are lost in time. Our observation of the universe has nothing special, it is a representative image of the universe and almost identical for any observer in space & in time. That shouldn't be so difficult to accept, it is simply a slightest extension of the cosmological principle. I understand that it may be difficult to swallow, since it goes against the "life of the Universe" accepted Theory. But when a Theory gives you the result that in a few billion years, the future scientists will live in a middle age universe made up of one single galaxy inside a huge void, I think that the least one should do is to raise some doubt.

OK. I am sorry. And I was wrong: I have no doubt about his intellectual abilities.

I am starting to wonder about your intellectual abilities.

But then, if you are correct, it goes again the cosmological principle. From Wiki https://en.wikipedia.org/wiki/Cosmological_principle What means "fair sample" in the above statement, when you seem to be confident that nature does not play "fair"? Do not forget that a difference in space means a difference in time. Objects that we are currently observing in the sky are in a different time than we are. The far away ones are in a long past. The cosmological principle depends on a definition of "observer," and contains an implicit qualification and two testable consequences. From wiki again At any location in the universe means also "spread over time", because each location is at a different time. What you seem to say is that "the universe looks DIFFERENT whoever and wherever you are because the universe is CHANGING" (sorry for putting words in your mouth).