michel123456

What units do they have? In this specific case.

I don't understand the question. If you make a diagram with meters on the X and seconds on the Y axis, the area of the diagram is meters seconds. Any point on the diagram has units meters seconds and describes the position of a point upon a line at a specific distance and time. The position of the train from Paris to Brussels at time T.

Here a nice article http://www.businessinsider.com/physics-atoms-empty-space-2016-9

What is reality made of ? I guess void represents 99,9%. The rest are particles. Fields. And interactions. In-between all these, Life.

It is Lorentz, not Lorenz https://en.wikipedia.org/wiki/Hendrik_Lorentz

I am not an expert on this, someone else will correct me. What I understand is that the Lorentz transformation gives you what on observer measures when observing a moving object. It does not give you anything about your own motion (because motion is relative). So answering your question, no, you will be accelerating all the time. But some observer far away will measure things bizarrely, like your mass increasing and your velocity never reaching Speed Of Light. Reversely, you yourself accelerating and looking back will measure the observer increasing in mass and never receding from you at velocity more than SOL.

Well, from my experience I am astonished with the fact that many people around me firmly believe in the importance of the zodiac signs. People including PhD. To the point that is not a belief anymore, it is presented as a certainty.

I didn't know they were hard drives in the 70's. I remember tapes & punchcards. Our first computer at the office (Aviette I cannot recall the rest) had no hard drive at all.

IIRC late Ilya Prigogine (Chemistry Nobel prize 1977) had the conviction that Time was the ultimate antecedent. Because without Time, the word "exist" has no meaning.

From my understanding of the paper, the conditions for it to work are rather extreme. Bender is right, in practice it doesn't work. Quoting the pdf "Ballet is not Lorentz invariant." Nice quote.

I think that is the point. If you try to spin yourself without any mechanical device, you may use your arms and the entire upper part of your body to begin spinning. As would do an ice skater. In this case your arms will use their own weight (momentum) for spinning the rest of the body. And as a skater, once spinning, you would pull by your own force your arms close to the rotational axis of your body (in order to spin faster) All this has nothing to do with the rest of the Universe IMHO. The stars around you play no role. The rotation is a relative motion, from a state at time stamp zero to another state at time stamp 1, then at time stamp 2, etc. The rotational transformation from one time stamp to another is an acceleration (because there is a change in direction). And the stars around play no role in this. IMHO.

Reminding the Mach's principle that stated that: You are standing in a field looking at the stars. Your arms are resting freely at your side, and you see that the distant stars are not moving. Now start spinning. The stars are whirling around you and your arms are pulled away from your body. Why should your arms be pulled away when the stars are whirling? Why should they be dangling freely when the stars don't move? I have enhanced in bold the part I'd like to discuss. Imagine you are an astronaut lost in deep space And you want to spin, like a dancer executing a pirouette Without a floor, without a grip anywhere, can you execute a pirouette? Ad if Yes (like an acrobatic diver), then will your arms be pulled away by the laws of physics? (last picture from https://prezi.com/c_0irhrx1vpo/pirouette-the-aspects-of-physics/

IIRC it was Ernst Mach who stated that an accurate description of the Universe should ideally involve only relative instances (quoting very loosely from my untrustworthy memory).

It exists in the plot of the Tintin's adventures comic book 'l'affaire Tournesol" 1956 in english https://en.wikipedia.org/wiki/The_Calculus_Affair From what i see over the Net such weapons exist. They are used for non-lethal weapons, not for destructing buildings.

Nothing was unclear. It is interesting that some instances are relative and some are constant. The most peculiar is SOL which is both relative and constant. Which raise questions about mass.

Good question. Maybe that is the mistake. We are so used to make the separation that we cannot put in our head at which moment you must do the union. In fact the union is always there. For example: What is between us and the objects in the picture? It is distance, because the objects are far away. And it is time, because it is the image of the objects as they were thousand years ago. So we see the objects different (smaller) because of distance and also different (younger) because of time. If you take a spacecraft and travel toward these objects, you will observe them changing (getting bigger) and evolving (getting older). At some point you may reach them and make the observation that the objects are not there anymore . But that does not happen because we are talking about stars. It happens also for close objects. It is intrinsic. The phenomenon does not start when distance gets big. The phenomenon is always there. In such a way that if you look around you, everything you see is located both in space & in time. And one should make the remark that everything around you is at a positive distance and at a negative time (in the past). There is no object at negative distance and at positive time (in the future). Which shows that time & space are irreversibly interconnected.

Belgian joke? A couple of Belgians go for skying in the French Alps. They are asking for the same ski instructor they had last year but they cannot recall his name. How was he? Can you describe him? _Yes he was wearing a suit with colors blue white red. _Hum, all instructors here wear that colors (it is the French flag). Do you remember anything else? _Euh yes, I think he has two anuses. _???two anuses, how do you know he has 2 anuses? _Because when he crossed with other instructors they always asked him :"How are you doing with your two arseholes?"

I am afraid we are heading out of topic. I don't think that the union between time & space has any relation with big or small. From a conceptual point of vue, the distance between my eye and my computer display is spacetime. I mean, it is not distance-only. My ruler has a length in spacetime. It has not a length separated from time. Somehow, Time is also part of my ruler. What I see around me, the objects in the room, are in spacetime. Under this concept, time is visible exactly the same way as distance is.

If I recall well, the lock switch (white arrow) designed for right-handed is under the right thumb. When a leftie like me uses the tool, the hand covers the lock switch. It means the tool is functionning when you take your hand off (because the lock switch is...locked). Dangerous.

Ha, spacetime curvature goes over my head too. Simply because gravity is an everyday phenomenon & spacetime curvature is not. Anyway I have the feeling that the union of Space & Time announced 100 years ago is still not a part of our understanding. For example, as an Architect I am measuring objects in space, while physicists should have told me that all objects are in Spacetime. But today's physicists actually tell me that I am correct and can continue to measure objects in space only. Although we all know (or should know) that it is incorrect, we are all continuing to discern space from time.

About unrealistic expectations & the statements from Swansont You can easily spot the lack of understanding even from the most educated: when they explain something and smile, it means they don't know. The more they get educated, the least they smile. When you get a Nobel prize he may simply admits "I don't know" without a shame. Unfortunately smiles are not easily detectable over the Net.

That the word "panic" comes from the ancient Greek god Pan. From Wiki Etymology The word derives from antiquity and is a tribute to the ancient god, Pan. One of the many gods in the mythology of ancient Greece: Pan was the god of shepherds and of woods and pastures. The Greeks believed that he often wandered peacefully through the woods, playing a pipe, but when accidentally awakened from his noontime nap he could give a great shout that would cause flocks to stampede. From this aspect of Pan's nature Greek authors derived the word panikon, “sudden fear,” the ultimate source of the English word: "panic".[1] ------------------------------------------------------- Effects Prehistoric humans used mass panic as a technique when hunting animals, especially ruminants. Herds reacting to unusually strong sounds or unfamiliar visual effects were directed towards cliffs, where they eventually jumped to their deaths when cornered. Humans are also vulnerable to panic and it is often considered infectious, in the sense one person's panic may easily spread to other people nearby and soon the entire group acts irrationally, (...) ---------------------------------------------------- So for the ancient Greeks, when someone got under panic, it was caused by the intermission of the god Pan. At the end of the Marathon battle, the myth says that runner Pheidippides encountered the god Pan who asked him why the Athenians didn't adore him. Pan had come to the battlefield and helped the Athenians to win the battle. Pheidippides answered that from now on, Pan would be adored by the Athenians (and indeed since then they create a temple to Pan in a grotto under the Acropolis. The concept that Pan helped the Athenians makes me think that when they saw the Persians run back to their ships it was for the Athenians a sign of panic.

This mesmerizing quote is close to 110 years old. Which means that when you look at space (look around you), you are looking at time also.

The next problem is that a single event cannot happen everywhere at the same time. Unless this same event happened in an area infinitely small (so that information about the Bang could spread in time= null). Which draw us back to the point-singularity. Even Allan Guth gets caught at it.

Time is an element of the continuum called spacetime. Trying to cut the continuum in parts lead to errors. IOW there is no Time by itself, and there is no Space by itself.