light speed and space exploration

why cant light speed be reached while flying ship in space? acceleration in space is somewhat cumulative so how come we cant use a long burning type engine (like the little ion engine that that probe/satalite used) to reach light or near-light speeds?

if a space ship of our current technology were flying around in space outside the gravitational pull of any nearby planetary bodies and it shut off its propulsion completely it would hold the speed it was traveling at indefinitely since there is no friction in space (or very little friction since space is relatively empty) and inertia is able to run the show. ok so now if it continued to accelerate using whatever means of propulsion it would continue to gain speed. at what point does this not work? could a ship in this scenario not reach light speed? why? how close could it come to light speed? like 99.99%? fast enough to get to alpha centauri in a decade or so?

i'm not talking warp drives or hyper space here i'm just talking about building inertia to the point of light speed. is that not possible and if so, why?

NASA and government space programs are lackluster and do not even slightly represent the general earth population's desire to explore space. why are civilian organizations not exploring space?

is there another habitable planet in a nearby system? one we could reach in a few lifetimes even at our current speeds? would it not be worth leaving immediately to find out? what if there is a human like culture developing on a planet in the alpha centauri system and its just not as far along as we are? shouldnt we go say hello?

imo space exploration should be such a high priority for everyone on the planet that we should literally build and fly our ships to every system near our own as soon as possible. why not? who cares about what britney spears named her baby i want to know if there are other species out there! even if it were a suicide mission i'd be the first to sign up for a trip to die in a nearby solar system

probes and satelites cant really react in the interstellar arena. you need to put humans into ships and send them places. sure we take more resources to keep alive than a machine but thats the whole point of exploring

I'm no expert but I have read that light speed is impossible due to the fact the closer you get to the speed of light the more massive you become.

We can't do it because we would need an infinite amount of energy, as the relativistic energy equation (below) shows: When v = c, the energy, E, required is infinite.

www.wonderquest.com...

i'm also no expert and i'm sure theres something i'm missing here but in space how does speed affect mass?

we are unable to calculate if an object is not moving in any direction because all known matter is moving so we have no point of reference

so if we're out in space and we go left rather than right does it take a different amound of energy to move since we are not holding still in the first place? i must not know enough about the mechanics of space if that is true because as far as i understood, moving in any direction in space was no more difficult than another direction as long as there was no matter or gravity to interfer

since really smart people say this is false then i must be mistaken right?

Originally posted by Kama
acceleration in space is somewhat cumulative

No it isn't. Firstly you couldn't break completely free of earths gravity. If you shoot a satellite off into space it wopuld eventually return to earth(barring the development of anti-gravity. Secondly the void of space represents 0 gravity not anti-gravity so you wouldn't accelerate unless you added energy to the mass(satellite).

Originally posted by Kama
i'm not talking warp drives or hyper space here i'm just talking about building inertia to the point of light speed. is that not possible and if so, why?

Because of e=mc*2. The faster you travel the heavier you get and thus you have to add more energy to make you go faster thus increasing your mass again.

lets say you did reach near light speed. time for you would slow down. it would feel to you that it only took several months or years to reach your destination, but in reality time for those back on earth would have proceeded at a normal rate. hundreds if not thousands of years, depending on how far you went, would have passed here on earth. in all that time the descendents of all those you knew would have long died unto several generations. the fact is, most everyone if not everyone, would have forgotten that you'd even left. so the gains in exploration would really be minimal. and that's only a one way trip, it'd take just as long to come back.
however i do believe also, that space exploration is vital to our society and planet. many advances in science and medicine have come from our meager venture to our own moon. someday soon we may develope new propulsion systems that allow for near light,light, or faster than light travel, but they aren't here yet. so untill then i think we'll all have to be satisfied with exploring our own solar system. which i think we should do more of.

"Because of e=mc*2. The faster you travel the heavier you get"

so if our solar system is moving at some insane speed around whatever center axis for our universe or whatever then that means we are moving at that speed too

so if e=mc*2 and we are moving at x to the left (lets say x is near light speed) then it would take infinite energy to move one inch to the right? i dont see how that could be possible since it seems like matter in space is able to move equally in almost all directions. maybe i just watch too much star trek...

Originally posted by danwild6


Because of e=mc*2. The faster you travel the heavier you get and thus you have to add more energy to make you go faster thus increasing your mass again.

You don't get heavier, you gain mass. Weight implies gravity and is relative to whatever gravitational body your measuring yourself on, which doesn't feature here. Mass and weight are two different things.

Conventional views aside, I don't understand how you can "gain mass" the faster you go. I was always taught that energy and mass are interchangeable, but, you cannot just create either. How does going faster increase mass?

I am quite comfortable with most other physics theorems, but cannot wrap my head around this one. E=MC2 is fine if you want to convert energy into mass (or vice versa), but using it to determine that FTL is impossible puzzles me. I am sure i am missing something here. How on earth (or anywhere else ) can your mass increase the faster you go?

[edit on 24/9/06 by stumason]

"it would feel to you that it only took several months or years to reach your destination, but in reality time for those back on earth would have proceeded at a normal rate"

i dont believe time works that way but for the sake of argument lets say i do

if i were in a little ship clipping along at c-1mph (so just a little less than light speed) i dont think time would work any differently for me than for the people back on earth. yes decceleration would be just as difficult as acceleration but i dont think it would involve time warping

"You don't get heavier, you gain mass"

sorry, i meant mass

the thing i dont understand is how it can take more energy to move based on the speed one is currently traveling at. if a ship were somewhere outside our solar system it would be "relatively" free of the gravitational pull of earth or our sun

ok let me try to phrase this question as best i can:

center of the universe is holding all stellar bodies in its orbit. lets say our sun is traveling at 100 mph and its orbit is slightly decaying with the center of the universe. if we had a ship in orbit of earth, then whatever speed that ship is traveling at would be in addition to the 100 mph of our sun around the center of the universe. so lets say the ship is doing 20 mph to stay in a stable earth orbit that would make its total speed 120 mph around the center of the universe (yes these numbers are bogus but accuracy is not the point here). the ship's engines are not on, its just floating around in orbit. heres the question: so e=mc*2 is saying that it would take more thrust (e) to go forward 1 mph than it would to go backward 1 mph, even tho there is no friction and inertia+gravity is holding the ship in completely stable orbit around earth?

yes, that's exactly how time works. the closer you get to the speed of light, the slower time progresses. it's the same for gravity wells, black holes, the closer you get the slower time goes. i recommend you read up on relativity, it should answer a lot of your questions.

"i recommend you read up on relativity"

google isnt working for me at the moment, know of any good sites for this kind of info?

Start here....

en.wikipedia.org...

Should give you an ample headache...

Trying to go through it now myself, but it's too late.....

[edit on 24/9/06 by stumason]

I too am no expert, but I have covered this stuff in high school and in college. Personally, I've never found any of the relativity stuff to intuitively make sense. It's kind of hard to wrap your brain around since, as humans, we live in a non-relativistic world. I'm almost certain this stuff is true, especially since physicists working with the big particle accelerators would've noticed something wrong with relativity by now. Anyway, here's a link that describes the various relativistic effects,
en.wikipedia.org...

well...i've searched ats for a thread discussing how to do the link tag thing...but couldn't find it, so if someone could explain it to me it'd be greatly appreciated.


here's a really good link i found for you archive.ncsa.uiuc.edu...

nevermind it did it for me! no wonder there's no thread on it! silly optimus! anyways, hopefully that'll explain what i was trying to say earlier, just go to the time dilation section

fascinating info

i'm still reading but i can at least answer one of my own questions

"i'm not talking warp drives or hyper space here i'm just talking about building inertia to the point of light speed. is that not possible and if so, why?"

the forces that hold molecules together are traveling at light speed. if an object were to travel faster than light speed, the forces that keep it together would not be able to keep up with the object itself and thus it would "come apart"

i'll keep reading and try to explain why we cant go almost light speed

stay tuned

this is interesting

"He also gave different expressions from those of Lorentz for the electric charge density and the convection current of an electron moving with respect to the moving frame (and moving with respect to the rest frame), and consequently derived expressions for the electric force on the moving electron which differed "also a little from those of Lorentz" (Poincaré 1905). He said the "ensemble of these transformations together with all rotations of space" form a group (but did not give details of the proof), and connected this group property with the impossibility of measuring absolute motion."

which means light speed or faster might be possible if some kind of field was keeping the molecules together or in a way making the forces holding those molecules together able to keep up with the molecules

"Poincaré noted that he was led by Lorentz's results to suppose "that inertia is a completely electromagnetic phenomenon, as it is generally considered to be since the experiment of Kaufmann" (Poincaré 1905)."

now that would be an interesting thing to observe, the breakdown of inertia as an object reaches light speed. wonder what would happen

"Einstein considered the equivalency equation to be of paramount importance because it showed that a massive particle possesses an energy, the "rest energy", distinct from its classical kinetic and potential energies. He was the first to suggest that when a material body lost energy (either radiation or heat) of amount E its mass decreased by the amount E / c2 - generalizing the idea of the mass-energy equivalence from the "fictitious fluid" proposed by Poincaré."

ok hold on

with all due respect to einstein, would someone please tell me WHY he came up with this? i dont even know HOW you would prove this without a frictionless arena which i doubt einstien had access to

"For example, an observer far from a black hole would observe time passing extremely slowly for an astronaut falling through the hole's boundary. In fact, the distant observer would never see the hapless victim actually fall in. His or her time, as measured by the observer, would appear to stand still"

at first glance this seems like complete bull to me, anyone know where i might find info to prove or at least theorize that time dilation is even possible?

I dont understand this either....

to me the only you could gain mass by approaching this velocity is if all the particles within the object began to seperate as you approach this speed and the distance between those particles begins to add mass..... but that doesnt make any sense because the distance between them would be nothing, so....

maybe it is a relationship on the matter itself....the problem maybe your energy for the velocity might start being absorbed by the matter of your craft making it heavier. of course, wuantum physocs blows this idea out the window since it takes certain amounts (no more and no less) to cause the particles to become more active.

I just dont know....I think everyone takes einstein's word for gospel and no one ever condiders the fact he may be incorrect in certain aspects of his theories.

i agree

i'm trying to figure out the whole time dilation thing right now and i'm not finding much good evidence

"since the 1960s there has been mounting indirect evidence that black holes might exist in places where, for example, a collapsed star's intense gravitational field allows nothing, including light, to escape. In that sense, the star disappears from the visible universe and forms what is now called a black hole."

how can gravity keep light from escaping? a lumi aethir was disproven so i dont see how gravity could stop light from escaping. i assume that a black hole cant really be seen because it actually is black and smaller than people may think. a black whole doesnt have to be big (refering to volume) it just has to be massive (refering to mass) to create lots of gravitational forces