grey arms

The most plausible FTL thought experiment i've come across involves the shadow of an object. Required is a powerful light source that is projected onto a flat surface. If we take an object (say a ball) and move it along between the light source and the surface, a shadow is created. We can assume that if the ball is directly between the light source and the surface then the shadow's dimensions will be equal to dimensions of a cross section of the ball (ie if the diameter of the ball is 10cm then the shadow's diameter is also 10cm). If the ball is moved horizontally we see that the horizontal dimension of the shadow increase. In essence, the furthermost edge of the shadow has moved a greater distance than the edge of the ball itself. So what happens if we move the ball across the surface at .99999c? Will the shadow move faster than c?

I'll make a point of it in future.

Like i mentioned before, fusion is what sustains a star once formed. The formation process is a little more complex. Nebulae form stars when they experience a gravitational collapse. The difficult part is ascertaining what causes such a collapse. Some theories attribute it to the explosions of other stars nearby. But its evident that there are stars that have formed in almost complete isolation. Granted, herme3's explanation sheds little light on the situation, but i would be wary of labelling this one case closed.

I'll agree with you to a point. However, you merely talked about the conversion of hydrogen to helium, which although accounts for the process during the longest part of a star's lifespan, does not account for all the material that is "burned up" (again i apologise for the ambiguity). Particularly in large stars, toward the end of the life cycle the star's temperature increases dramatically at which point the fusion of helium and heavier elements occurs. In fact, a supernova is the result of such heavy fusion processes (coupled with strong gravitational forces). In supermassive stars even silicon and iron are products of fusion. It is the relatively short period in which this fusion (and the resulting supernova) occurs that a star loses most of its mass. Technicalities aside, the point is a star loses far more mass in its lifetime than a black hole of relative size is likely to gain.

Fusion does not explain the origin of stars, only the process by which they remain. And the evidence is not great enough to claim that every star was created shortly after the big bang. An interesting model, herme3. I would have to object, however, on the following grounds: 1) Stars produce vast amounts of heat energy, which is propelled outward to sometimes great distances. The mass of an expired star is significantly less than that of a star at the beginning of its life cycle (as it has burned off its fuel mass). 2) Generally, black holes are tiny compared to the stars from which they are formed. Most have a lifespan far less than the stars from which they are formed. Therefore, the amount of energy or matter propelled outward by a star is far greater than the energy it's black hole will "suck-in". If your model is accurate, we would expect to see new stars created constantly, and these stars will become smaller and smaller over time. Then we must consider the vast majority of observable stars, that do not form black holes upon exhausting fuel sources.

There are countless objections to the logical possibility of backward time travel, but rarely do i find discussions pertaining to the displacement of matter that backward time travel would inevitably cause. Let me give an example of what i mean. Say you have invented a time machine prototype that's about the size of an apple. You are able to adjust a dial on it so that it can appear at any time in the past or future that you desire. Now lets imagine you put the device on a table in the kitchen at 8pm friday and set it to travel back in time exactly one day. It arrives at the same place on the table at 8pm thursday. Now things get tricky when we try and imagine HOW it gets there. In my experience there are two common assumptions made about the path of the machine. It either (a) vanishes from its position and enters some form of "time-warp" dimension only to reappear at the set time, or (b) remains in its position and witnesses time unfold backwards all around it (like in H.G Wells' novel). In (a) we can plainly see a violation of the basic laws of the conservation of energy. At 8pm thursday at point P on the table we find a physical object that did not exist one moment prior, meaning that the total mass of the universe has increased immediately by the mass of the time-machine. Similarly, the total mass of the universe a moment after 8pm friday decreases by the mass of the device. If we adopt the many-worlds hypothesis for such a situation, and say that a new universe is created at 8pm thursday, a universe with slightly greater mass, then we would have to say the same for 8pm friday, where a universe is created with slightly smaller mass. What, then, happens to the original universe (assuming it cannot increase or decrease in mass)? (b) seems slightly more consistent. But the problems are obvious. So the time machine is set and turned on. What happens? If it obeys the laws of conservation of energy, it must remain at P even after it is set. In fact, it would be difficult to determine whether anything at all has happened. From the perspective of someone inside a machine though, the world is witnessed in backwards motion. Or is it? If the machine must remain at P even after it is set, so too must the person inside. We can asume that neither the device nor the person inside is experiencing a backward flow of time AFTER 8pm friday, so they would in fact experience forward flow as normal. So then, what EXACTLY is experienced at P at exactly 8pm? Does the person experience the backward movement of time before 8pm and the forward movement of time after 8pm simultaneously? My final objection can be seen in both scenarios. What happens if, at 8pm thursday, at point P on the kitchen table, someone has left another object? Would the time machine displace the matter of the coffee cup you left there accidentally? Can two things exist in the same point in space and time?