i dont think there is any propelant existing that can bust the machine to move with speed of light …

Riper, I think you may be missing one of the central ideas of this thread: according to the scientific theory best supported by experimental evidence,

relativity, no propulsion of any kind can accelerate any machine to the speed of light in vacuum c (exactly 299792458 m/s). This is not because no propellant has enough “muscle”, but because the amount of energy required to do so is infinite. This is due to a phenomena known as mass dilation, or relativistic mass. The formula for the energy Er required by a perfectly efficient mechanical system to accelerate a mass M to speed u, derived from the basic postulates of relativity, is [math]Er = M c^2 \left ( \frac{1}{sqrt{1- \left ( \frac{u}{c} \right )}} -1 \right )[/math]

The non-relativistic, classical mechanical formula for the energy required by a perfectly efficient mechanical system to accelerate a mass to speed u is [math]En = \frac12 M u^2[/math]. If you compare the energy calculated by the 2 different formulae, you’ll see that, for small speeds we ordinarily encounter in vehicles, the 2 energies are nearly the same. As the speed approaches c, however, Er becomes many times greater than En, meaning that the En shouldn’t be used for calculations involving such speeds. Here’s a small table of examples:

Speed u Er/En
.0000001 c (car) 108 km/h 1 (not really 1, but too close for my calculator to distinguish)
.0000008 c (plane) 863 km/h 1
.000001 c 1079 km/h 1
.00001 c 10793 km/h 1
.0001 c 107925 km/h 1.0000000074
.0002342 c (*) 252761 km/h 1.00000004113062547
.001 c 1079253 km/h 1.00000075
.00205 c (**) 2212468 km/h 1.000003151885782272
.01 c 10792528 km/h 1.00007500625054
.1 c 107925285 km/h 1.007563051842415
.5 c 539626424 km/h 1.237604307034012232
.9 c 971327564 km/h 3.195450219026216442
.99 c 1068460320 km/h 12.42487919617051118
.999 c 1078173596 km/h 42.81813754120330883
.9999 c 1079144924 km/h 139.4527810654887706
.99999 c 1079242056 km/h 445.2236179659762919
.999999 c 1079251770 km/h 1412.216740358686725
.9999999 c 1079252741 km/h 4470.136960830329925
.99999999 c 1079252838 km/h 14140.1359418890071
.999999999 c 1079252848 km/h 44719.35965061485308
.9999999999 c 1079252849 km/h 141419.3562655933761

The “*” above stands for the fastest manmade vehicles flown to date, the Helios probes. The “**” stands for a hypothetical “dream machine” spacecraft I speculated was possible with present-day technology. Both are discussed in and around the post

‘SR confirming experiments, spacecraft speed records, "dream spacecraft missions"’. I recommend reading its entire thread, “Time dilation does not make sense to me”.

… and even if there is who will control it? we cant even control 400km/h.

Sure we can. Most commercial jet airliners cruise between 800 and 900 km/hr. Geostationary communication satellites orbit at about 11,068 km/hr. The world land speed record, set in 1997 by the

ThrustSSC jet powered car, is 763.035 km/hr.

Controlling vehicles has much more to do with minimizing unexpected forces than with the vehicle’s speed. A bicycle going 10 km/hr on a rough trail can be way more difficult to control than a spacecraft going 2 million.

the surface of that machine has to be strong enough to withstand the friction against the air particles, unles it is in space.

You can be pretty certain that any machine traveling more than 10,000 km/hr or so won’t be doing it near Earth. Although structural strength is not a major issue, air friction, which ultimately results in heating of the aircraft, is. The

SR-71 Blackbird, widely considered the fastest aircraft ever flown, is capable of sustaining a speed of “only” about 3,600 km/hr, and that only at an altitude of about 24,000 m, where the air is much less dense than near the ground. Although made of very high temperature materials (titanium and composites), and designed to redistribute and shed as much heat as possible, the SR-71’s maximum sustained speed is due primarily to the limit of it to withstand a maximum skin temperature of about 430° C.

An experimental, unmanned

X-43, which has very advanced skin cooling systems, reached a speed of 12,144 km/hr (about .00001 c) at an altitude of about 30,000 m during its 10 seconds of self-powered operation.

Making an aircraft capable of sustained speed much higher than the SR-71’s 3,600 km/hr would require a much more effective cooling system than any previously designed. This is a very fun engineering challenge to think about, and one that has a lot of valuable practical applications.

Even if the air friction problem and energy problems could be solved, the simple mechanics of keeping a vehicle close enough to Earth to be within its atmosphere at speeds approaching c appear prohibitive. The usual definition of “within the Earth’s atmosphere” is below an altitude of 100,000 m, or within about 6,478,137 m of its center. To maintain a circular path at this radius at a speed of .01 c (10792528 km/h) would require an acceleration of about 1387367 m/s/s (141568 gs), of which Earth’s gravity could supply only a bit fewer than 10 m/s/s (1 g). It’s hard to imagine any machine capable of exerting or withstanding the force of such an acceleration.

but some russian and german research intitutes are working on it.

Really? If you know of such research, please tell us about it, but given the tremendous engineering difficulties of making any vehicle capable of speeds even approaching .01 c, I’m doubtful any legitimate such research exists.