michel123456

(emphasis mine) Yes, but isn't that an explanation based on wishful thinking? Who said that a force is applied on a surface? A force is applied on masses (or charges). Newton showed that a force is applied as if all the mass was on a single point. Where is the surface? That is understandable. But still weird since there is clearly an acceleration involved in the concept of force.

The inverse square equations are about force. And force means time. I mean both Newton's and Coulomb's are expressed in Si unit of Newton where 1 N = 1 kg.m/s2 Without the s2 it does not work.

I don't get it. You talked about a vector field in 3D. Without time?

Our world is 4D.

Very interesting question. At my knowledge there is no clear answer. Some speculate that gravity relates to electricity but the concept has been debunked many times. My own quest is focused on the "square law". Why are we obliged to use the square of the distance in both laws? The answer is: in order to make results coincide with observation. So "the-distance-that-we-observe" is only the square root of "the-measure-that-we-have-to-use-in-the-equation". And with an outstanding, an incredible, an unbelievable characteristic: the unit of the observed distance is squared. So, the "square law" does not say that you multiply a distance by itself and obtain a larger distance, no no. The "square law" says that you multiply the distance by itself and obtain a SURFACE that you DO NOT observe. If the "square law" acts the same for Coulomb's law and for Newton's law, to me it means that the "square law" has something to do with spacetime.

What happened after this thread ? Did Lawrence Krauss get the questions?

Maybe the arrow of time reverses at the EH. Like turning a sock inside out.

Oh yes, I missed the 10,000. My bad. It can, it was unclear to me that 8,5 km/s was initial velocity. At return , at the point where the rocket cut off, the rocket in free fall should travel at the same velocity 8 km/s. If the diagram shows the situation from cut off and after, it must be perfectly symmetric. If i understand correctly, the spacetime diagram on the link simply does not show the departure of the rocket- added by me on the left down part of the diagram. See below

Once the engines shut down, it's free fall. The only acceleration is that of gravity. I am O.K. with that. Why? because free fall is accelerated motion. Why? A rocket going up after the engines shut off is still in free fall. Yes but then the engines were stopped before reaching the 10 km, let's say at 5 km altidude, and then the resulting diagram would be asymmetric since the part from launching till 5 km would not have been in free fall. Yes. All clock measurements are comparisons between clocks. A clock that runs fast/slow does so when compared to some other clock. So there must have been another clock at rest upon the surface of the Earth, which was not in free fall condition.

But the rocket was launched. That is not "free fall". And 8.5km/s is not "free fall" On the other hand If the engines stopped at 10 km as Enthalpy suggests, then the first part of the diagram must be erased and only the return phase could be considered in free fall. I suppose. And on the third hand, there must have been another clock at rest in order to get the measurement. I suppose- again.

Sorry for the Out Of Subject but the description of the vessot experiment in your link makes me raise some question: (emphasis mine) Where was the clock?

With feathers. And making eggs. No bikini needed.

Anyway the 2 processes are related http://www.plasma-universe.com/Image:Electric-candle-flame.jpg

An answer would be that all possible things do exist but not at the same place at the same time. Sure time is involved. When you put object B where object A used to be, you put object B at the same spatial coordinates but not at the same time coordinate. The universe is 4 dimensional (at least) so you need 4 coordinates to describe an event in spacetime. And if you want to displace an object from one spacetime coordinate to another, laws of physics say that you need time to do that. You cannot move in time zero. If it wasn't so, then objects A and B at different spatial coordinates could have been the one and same object. -------------- (edit) That still doesn't answer your philosophical question about the cause of existence of course.

There is a lack of explanation. What is this? How large? Is this a side view? An aerial view? What are those "legs" in one of the picture?

In this case all members should have a huge number of visitors. I don't like NSA, I love NSA!* *paraphrasing 10cc's Dreadlock Holiday lyrics.

This is from another (closed) topic, dear Moderators will judge if it goes against the rules or not. Michel posted ACG52 answered Which is absolutely correct. But if you look closely to the analogy of the observers in free fall and compare to the Universe, you obtain the following. _In the analogy, the "receding" is caused by 3 phenomas a. the same and constant acceleration of the 3 jumpers b. the same direction and same path (or parallel path) c. the delay of 1 sec at the starting point between the jumpers. _in the Universe c. the delay is caused by the speed of light, not by a delay at the starting point. So in the universe there is no "guy who jumped out of the plane next to you". All are delayed. b. in the universe there is no indication that all objects (galaxies or galaxy clusters) have the same direction or are actually on a parallel path. So indeed that would be a very bold statement, with only fragile support the famous "dark flow". a. the same and constant acceleration could be caused either by gravity, either by some other phenomena (dark energy) since IIRC it is observed as being not constant. Then you have the big objection: In order to counter this objection, one has to imagine a truly immense earth-object, infinitely big and infinitely far away, so that all objects from the observable universe are on a parallel path, like the sun rays reaching the Earth parallel to each other .

You are on an airplane with a parachute. A guy before you jumps in free fall. After a second you jump in free fall The next second a 3rd guy jumps in free fall. Looking in front of you you will observe the first guy receding from you. Looking back you will observe the 3rd guy receding from you. All 3 observers will observe each other receding.

If you want to say that accelerated objects moving along the same path are observing each other as receding, then yes.

Keeping track today: Michel has 3,738 posts divided by rep 321= 11,64 And wow! 40,191 profile views? Is that all the NSA employees?

Is that me or have the up/down arrows from the rep system disappeared?

lost in translation. Thanks.

What do you mean by "scroll" and "reciprocating"? ------------ Notes: 1.if your refrigerator stops functioning normally, try to take the power wire off for 30 minutes, then plug it in back. 2. the data sheet is inside the refrigerator somewhere, next to the door hinge or behind the boxes in the bottom.

Why? Do you have the hole?

Are you talking about the ground effect ?