Jacques

No answer yet.... Just want to bring to your attention that if spacetime is something, then everything in the universe is connected, everything is in contact with everything. Does it make some sense ?

Is space-time something or is it simply a background used to mesure thing ? At first, I was thinking that it was just a mathematical construct used as a background to mesure thing, but now I am not so sure. Spacetime has some property permetivity and permeability. Also it can be bent, it can be draged by spninning body and may have other property that I am not aware off. That make me think that it is something, that it's not only a mathematical construct. Then the universe is composed of matter, energy and spacetime. If it is correct to think about spacetime as something then what is the difference with the old theorie of aether ? Thanks in advance for your answers.

Get off the earth reference frame and use some distant star for reference and you will understand that the moon is rotating on it's axis once a month. Imagine yourself an the moon and observing a star near the eastern horizon. What will happen after a few days ? You will obseerve the star rising in the sky and after 14 day you will see it setting at the western horizon.

Hi I also missed that eclipse of the moon... But take a look at that site ! http://spaceweather.com/eclipses/gallery_03mar07.htm'>http://spaceweather.com/eclipses/gallery_03mar07.htm http://spaceweather.com

Does it mean that GR cover all SR ? If the spacecraft suffer an acceleration in its speed, I think that SR apply at each infenitisimal time, and we need to make the integral of each delta time dilatation... Is GR doing the equivalent to that ?

tsolkas what does the Galileo experiment tell us that no matter the masses they will hit the ground at the same time or in other word acceleration is independent of the mass, so a mass increase caused by relativity woun't change the accelaration of the falling mass.

From wiki: Maybe the contact area is already saturated in the case of the ligther car... The area of contact of the tire is small compared to the weight of a car , and ruber maybe is easily saturated...

A faraday cage will also protect you from lightning http://en.wikipedia.org/wiki/Faraday_cage

I don't know why you belive that. Let take a simple example. Let say the pin point source is 1mm diameter and the transparency is 10cm from that source and the screen at 1m from the source, then a detail of 0.1mm on the transparency will be on the screen 1cm+0.1mm. It is easy to get better with a simple lens.

Sorry but I can't get it. For me you cannot convert kg to seconds. You can get the Compton time for a mass with your formula, but it is not a conversion from time to mass. Am I missing something here ? Is it only a language shortcut ? Thanks

It's easy to find an achromatic lens who will give a better definiton than a pin point light source. With a lens, you won't need a pinpoint source, just need any light source with a frosted glass to distribute the light evenly. When I was a kid, I build a projector like that and the key factor to minimize distortion is by having the maximum focal lenght, but that reduce magnification...

Thanks Martin Is there any use or meaning of the Plank mass or is it only a curiosity ? If I remember correctly the Plank lenght is the smallest possible lenght, but the Planks mass is surely not. Also trying to convert kg to second isn't it like trying to convert apple into a car ? I can find a number X the number of apple that can fit in a car, but that number X doesn't mean that if I have X apple it's the same has a car...

How does the Plank mass defined ? Is it the solution to that equality who define the Plank mass ? Thanks

Why not simply use a lens between the transparency and the wall ???

That water wheel doesn't respect that rule...

You are right Swansont Encipher any new developpement in your slow yoyo competition ? Thanks

Ok one big difference is that you use a 1mm diameter axel and in my setup I used a 2mm axel. My idea of moving the center of mass out of the axel will create a two time cycle: The first half of the cycle begin when the center of mass is just pass over the axel, the torque is in the direction to unwind the yoyo. The rotation speed increase and also the linear speed. When the center of mass is at the lowess point in the rotation the torque is zero and the rotation bring the center of mass on the other side of the axel. The torque is in the opposite direction slowing the rotation until the center of mass pass over the axel again. Hope you understand the idea The first half cycle convert potential energy to angular momentum and the second half of the cycle convert back some angular momentum back to potential energy. I think that by fine tunning the unbalance you can achive any speed. If to much unbalance the yoyo won't go down so there is a limit to the unbalance. I would use a perfectly balance yoyo an used some putty to unbalance it and do some experiment to see how much putty to add and where to add it. Important to keep it balanced horizontally

So if my calculations are good, 62 sec is far less than what encipher did and by a factor that is more than any improvement only by work on the geometry. If you do the calculation with the square geometry, you will still have less than the 3 minutes you achive and by the others result. Some other factor made the difference between the theory and the experiment. I came up with the concept of a yoyo that will take more than an infinite time to travel the 2 meter But it is agains the defenition of a yoyo. A yoyo must rotate. I thought that an inbalance in the real yoyo made the difference. A small imbalance will displace the center of mass from the geometric center. The torque will vary like an offset sine. Chirstmass diner is waiting will continue later....

Ok I will give it a try using g=10m/s^2 the force is mg = 1kg*10m/s^2 = 10 Newton the torque t on the axel of 1mm radius = F * r = 10 N * .001 m = .01 N.m the moment of inertia for a 10 cm radius cylinder is MR^2 = 1kg * (.1m)^2 = .01 angular acceleration = torque / moment of inertia = .01/.01= 1 rad/sec^2 on the axel 1mm = 1 radian then 2m = 2000 radian 2000 radian = 1/2 angular acceleration * time^2 sqrt 4000 = time = 62sec It look like a short time... What do you think of it ?

How did you found that ? I google "moment of inertia and I found [math]\frac{1}{6}MA^2[/math] on that site http://www.physics.uoguelph.ca/tutorials/torque/Q.torque.inertia.html If you bring A to R you have [math]\frac{2}{3}MR^2[/math] I am not very good in math but I would like to know theorically how long it will take the yoyo if we use a 2 mm radius axel with the cylinder geometry [math]MR^2[/math] Thanks

Use a round geometry, concentrate the mass on the edge and minimize the axel diameter, maximize the yoyo diameter. Use 2 large rings, a few spokes to connect the rings to the axel.

Do you live in the country or in a city or a suburbs ? If you are not living in the country, do you have a car and a site where you can setup your scope ? The quality of the sky available is a big factor. It is useless to have a big scope if your observing site is light polluted and even worse for astrophotography. You must know that the important factor for a telescope is the diameter of the mirror, not the magnification. The second most important thing if do astrophotography is the quality of your mount. For photo the best is CCD camera. The type of telescope in your link is a good choice for a first telescope: low cost and enought to see interesting celestial object.

0 KW Pratically it's impossible to 100% efficiency so you will lose energy for nothing

Hi, the pushing gravity model is develloped here: http://metaresearch.org/ That model need faster than light particle. I prefer the Gremlin eating space model.!

It may interest some of you : On Sunday, Nov. 19th, Earth will pass through a stream of debris from comet 55P/Tempel-Tuttle. The result: a shower of Leonid meteors. "We expect an outburst of more than 100 Leonids per hour," says Bill Cooke, the head of NASA's Meteoroid Environment Office in Huntsville, AL. http://science.nasa.gov/headlines/y2006/14nov_leonids.htm