What stops matter from exceeding the speed of light

ehcuob · Dec 9, 2006

Lets say you have a drone craft in the dead of space its nuclear fusion engine is thrusting and has now reached 10 million miles per/sec, no lets say no local gravity from no matter, no gas, nothing but space it continues to acelerate, up to now no force has resited the aceleration, we are measusing 2 g's (offcoarse so humans can ride ) in these early stages absolutely no resitance has being measured other wise you could have measured it at the moment of blast off. Recall the laws of motion, so with nothing opposing. does some thing crop up lets say at 50 million or maybe 179.99999 million miles per second, at what point 50% 80% 90% will we see this barrier?

docm · Dec 9, 2006

Gradually from zero velocity, exponentially. Remember E=MC^2; mass and energy are equivalent. Also: we're talking about the speed of light in a vacuum, not though a transparent medium where it travels much slower. As your space ships velocity increases so does its mass. As its mass increases so does the amount of energy needed to accelerate it further. As its speed approaches the speed of light the amount of energy required to accelerate further approaches infinity, which is of course an impossible situation. More here; http://en.wikipedia.org/wiki/Speed_of_light <div class="Discussion_UserSignature"> </div>

pyoko · Dec 9, 2006

c is 299,792,458 metres per second. As your ship nears this figure, the relative mass will head towards infinity, and the amount of energy or thrust needed to reach the 100% mark will also tend towards infinity. Think of an exponential graph. Your ship will head toward the 100% mark but never reach it. <div class="Discussion_UserSignature"> -pyoko the duck It is by will alone I set my mind in motion. </div>

tdamskov · Dec 9, 2006

To answer your question ("when is resistance measured"): Anyone on your hypotetical spaceship will be unable to measure any resistance. Using clocks onboard the ship and measuring relative motion to the surrounding starfield, it will show that the spaceship meets no barrier and can keep accelerating beyond the speed of light. The only odd thing happening is the blue- and redshifting of stars ahead of and behind the craft. However, an observer standing on a planet will still see the spaceship approaching the speed of light yet never reaching it. This paradox is resolved by the fact that while the spacecraft is approaching the speed of light, the added acceleration slows down time on the ship instead of adding velocity. So there really is no problem going faster than light for a passenger onboard your ship, they will just have to put up with everyone they knew being dead when they arrive, while having aged only a few months themselves.

pyoko · Dec 9, 2006

very good explanation tdamskov. <div class="Discussion_UserSignature"> -pyoko the duck It is by will alone I set my mind in motion. </div>

alokmohan · Dec 10, 2006

Speed of light is same irrespctive of frame of reference.Possibly yo u are wrong.

lukman · Dec 10, 2006

In the presence of Newton's first law (A body at rest remains at rest, and a body in motion continues to move in a straight line with a constant speed unless and until an external unbalanced force acts upon it.) and the absence of external force such as gravity and drag, accelerating from 0-10,000m/sec or from 290,000-300,000m/sec require the same energy. So technically, it is possible to travel FLT speed. So, your explanation is the most make sense. <div class="Discussion_UserSignature"> </div>

SpeedFreek · Dec 10, 2006

But Newtons laws don't work when dealing with speeds close to the speed of light, which is why Einstein had to come up with his general and special theories of relativity. As stated above, the closer you get to c, the more your mass increases and time slows down for you. At c, you would have infinite mass and time would stop for you. Matter cannot be accelerated to the speed of light, because to do so would require infinite energy. Only so called mass-less objects can travel at the speed of light (i.e. photons). But strangely enough, this does not mean that a journey of 5 light years actually takes 5 years at the speed of light! Two phenomena occur when accelerating towards the speed of light - time dilation and length contraction (see the Lorentz transformation for more details). Say we manage to make a spaceship that can accelerate to 0.999c (this would take an immense amount of energy to do, but is still technically possible). Special relativity (specifically the lorentz transformation) tells us that at 0.999c, a journey of 5 light years would only take the spaceship a little under 3 months due to time dilation. And due to length contraction, the distance to the spaceships destination would shrink from 5 light years to 0.22 light years at this speed. Now at 0.999c a journey of 0.22 light years takes a little under 3 months! But of course, this is only relative to the spaceships frame of reference! To an observer watching from an inertial frame of reference, it would still look like the spaceship travelling at 0.999c takes 5.05 years to make the 5 light year journey. This is what throws up the so called "twins paradox". If your twin brother makes that journey, turns round and comes straight back home, to you it would look like the journey took him around 10.1 years. But when he returned he would have aged only a little under 6 months! So, you see, the spaceship doesn't exceed the speed of light and yet <div class="Discussion_UserSignature"> _______________________________________________ SpeedFreek </div>

lukman · Dec 10, 2006

Agree, but why the light speed is so special that we cant exceed it? is it something like sound speed in the air? <div class="Discussion_UserSignature"> </div>

oscar1 · Dec 10, 2006

E=MC2 is indeed the reason why you can't go faster than the speed of light. It is however fairly difficult to imagine this from that simple-looking equation. Perhaps you should look at it this way: You yourself and your craft are made up of matter. That matter originated in the singularity from which our entire universe springs. And that matter wishes to go home to that singularity; it expresses this wish by means of gravity. Now if you would try to escape, you would indeed need to keep on accelerating. But in order to be able to reach escape velocity, you would need an amount of energy equivalent to all the mass available in the universe. You'd take the universe with you that way, and hence, you are not getting anywhere near leaving it. In other words, you yourself, being part of the universe you are atempting to leave, are the resistance you encounter.

SpeedFreek · Dec 10, 2006

Agree, but why the light speed is so special that we cant exceed it? Yup! That's the million dollar question! I expect that if I could answer that question properly, I would be up for a Nobel prize! The speed of sound in air is not special. Many things can go faster than the speed of sound. The speed of sound in air on Earth would be different from the speed of sound in Martian air. The speed of sound changes depending on which medium it is passing through (somewhat like light) but the difference is that sound isn't a particle. Sound is caused by something making other things vibrate. Sound "energy" is transferred by atoms bouncing off of each other. When there aren't enough atoms around for the sound to bounce along (i.e. in a vacuum) the sound degrades and dies. Whereas light is an independent particle (which does exhibit wave like properties). Photons are a unique kind of particle, exhibiting unique properties. Nothing can naturally travel faster through a vacuum than a photon. Why? Well, that I cannot answer. All I would say is that it seems like the various forces and constants in the universe are intrinsically linked. The speed of light, gravity, mass etc are all linked together by the laws of physics. I think we would need to understand gravity (which we don't yet!) to put us on the path to understanding why the speed of light is how it is. <div class="Discussion_UserSignature"> _______________________________________________ SpeedFreek </div>

vandivx · Dec 11, 2006

"Why? Well, that I cannot answer. All I would say is that it seems like the various forces and constants in the universe are intrinsically linked. The speed of light, gravity, mass etc are all linked together by the laws of physics. I think we would need to understand gravity (which we don't yet!) to put us on the path to understanding why the speed of light is how it is." -------- what you just said here is so rare for anyone to say and so true just about anybody who understands special and general relativity would say that we know how gravitation/mass works as well as why nothing can go faster than the speed of light special relativity doesn't say why speed of c is constant, it just takes that as a given fact and builds on that and all the rest like that mass cannot exceed the speed of c just follows from that, that is from that starting base of constant c of which nobody knows why is it constant, to understand that we would need a real physical theory giving us a physical picture, not just mathematical equations vanDivX <div class="Discussion_UserSignature"> </div>

SpeedFreek · Dec 11, 2006

Yes, that is indeed the crux of the matter ! (No pun intended!) We may think we understand the mechanics of how things work, but we aren't even close to knowing why those mechanics are set up in the way they are. <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> _______________________________________________ SpeedFreek </div>

lukman · Dec 11, 2006

Alright... But for the speed of sound, also special. True if the speed of sound is relative to the medium it travels on, However, sound wave cannot move faster than it's max speed. Example, the top speed of sound in the air is 344m/s, in a bar steel is 5000m/s and so on. So even if a sound is produced on a 100m/sec moving train, the speed will remain at 344m/s in the air. not 344+100m/s. Unless the sound is produced inside the train where sound will move with the surrounding. <div class="Discussion_UserSignature"> </div>

SpeedFreek · Dec 11, 2006

Good point! Your moving train example illustrates another way in which sound and light are similar - doppler effect. As you say, the speed of sound leaving a train moving at 100m/s is not 444m/s. The sound moves at 344m/s but the sounds frequency is changed. This is the same as light, which is why we can measure the relative speeds of objects in deep space by their doppler effect, red shift and blue shift. As to sound being a constant... What is the maximum speed of sound possible? What medium would this be in? Whatever the answer, it has to do with the ability of atoms to bang into each other! Now what ultimately limits this process? <div class="Discussion_UserSignature"> _______________________________________________ SpeedFreek </div>

MeteorWayne · Dec 11, 2006

If Einstein's view of the Universe is correct, the speed of light is the hard limit of reality. The rest of the Universe is constructed around that limit. So far, he's been right.... <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

tatsit · Dec 11, 2006

I believe Einstein was partially wrong. His theory of light speed being the cosmic speed limit is based only on visual sight of light. E=mc2 -- i do not see how splitting atoms relates to the speed of light? Also may physicists state that at the point of big bang for the first 300,000 years matter exploaded faster then the speed of light. Einstien also refused to belive in quantum mechanics. Dont get me wrong, he did great work unifying gravity and electomagnetics - but his cosmic speedlimit is wrong, and not to mention his theory on space time fabric - time is a man made concept to put an understanding to the concept of time. Time is not a substance, a particle or a proton, it has no quartz or neutron there for a force as weak as gravity can not effect time. Time is a constant, because its man made concept to help understand "time" you can not warp something that does not exist.

SpeedFreek · Dec 11, 2006

Time is not a substance, a particle or a proton, it has no quartz or neutron there for a force as weak as gravity can not effect time. Time is a constant, because its man made concept to help understand "time" you can not warp something that does not exist. Time is as real as space. Just as space has no substance or particle, neither does time. Space exists and we describe it using dimensions. Time exists and we describe it using duration. We can measure both, relative to ourselves. Just as there is no basic unit of space, there is no basic unit of time. We made up the definitions, using our own calibrations. We define terms like metres, seconds and light years using our own scales, but without humans the phenomena of space and time would still exist. Just ask a radioactive isotope, which has a half-life! However we describe the time it takes to lose half its radioactivity, it would have taken the same length of time whether humans exist to measure it or not. Time is not therefore a man-made concept. Seconds are a man made way of measuring time, the same as metres are a man made way of measuring space. As to the idea of "warping" time, well we have yet to see special relativity disproved when it comes to things like time dilation or length contraction. All experiments so far seem to confirm it. So it seems if you travel at relativistic speeds, time slows for you and space contracts for you. Both seem intrinsically linked. <div class="Discussion_UserSignature"> _______________________________________________ SpeedFreek </div>

kmarinas86 · Dec 11, 2006

The rate of time is a tempo. A chaginging rate of time is a changing rate of tempo. The tempo which light follows depends on the propogation properties of the medium (or lack thereof) through which it travels. If light follows a different tempo at a particular place, so will any objects that place. "tempo" is Italian and Portuguese for "time". beats per minute cycles per second

alokmohan · Dec 12, 2006

Postulates of theory of relativity are undisputed so far.Read a standard text book.

oscar1 · Dec 12, 2006

I'd like to know Steve, would you classify quantum foam as matter? I suppose one could, but then we'd have to call a brick a house too.

lukman · Dec 12, 2006

E=mc2 -- i do not see how splitting atoms relates to the speed of light? - I dont see the relationship too, but the formula is definetely very reliable for many uses. Also may physicists state that at the point of big bang for the first 300,000 years matter exploaded faster then the speed of light. - Space was created so fast that it seemed to move the matters faster than speed of light, so it wasnt the matters which moved FTL. Funny, but i have this theory, at the edge of universe, heat creates space, but heat cannot create space in a space. Because the only thing missing and the only reason the darkness in the night and the reason our universe is not over heated. Energy (heat and light) is missing and compensated by new space created. So now, space, similar to matter, is a form of energy. -) <div class="Discussion_UserSignature"> </div>

SpeedFreek · Dec 12, 2006

A very good post Steve! Time is a very difficult concept to understand fully. I will admit to reifying the concept when maybe I should be more circumspect with my desciptions! <img src="/images/icons/wink.gif" /> I should though point out that you describe time as a duration of processes where I simply described it as duration. Duration means the interval between events, so I really meant much the same thing. Your explanation is very good, and I cannot argue against it. And yet still I find myself asking questions. Is time a dimension? A lot of people say it isn't - that it doesn't exist in the same way that space does. You seem to be saying the same thing. You describe it as an abstraction created from regular processes. And yet, everything in the universe at the macroscopic scale is affected, or even controlled, by time. To me, time seems as real as gravity (which we can measure, but does not seem to exist as a thing and we cannot point to it!). We see gravity only by the effects it has on mass (and time!). We see time only by the effects it has on matter (aging?). Is gravity a process in the same way that time is? Does this mean that time should be considered as a force (like gravity) rather than a dimension? I don't feel I am getting across the words properly! It is like time is something that may need a separate description all of it's own. It just seems to me that time is so linked with space that it has to play a fundamental part in the laws of physics. Just because we can only measure time, but not see it or touch it, doesn't neccessarily mean it only exists as a concept, like infinity. I wouldn't be surprised if when, one day, we actually understand how the universe works, time will play a larger part in things than it is currently given credit for! <div class="Discussion_UserSignature"> _______________________________________________ SpeedFreek </div>

oscar1 · Dec 13, 2006

I originally learned about Quantum Foam by something I read by the hand of Dik Bouwmeester, but that I read in a Dutch publication ('Natuur en Techniek'). So have a look at this instead: http://www.astronomycafe.net/qadir/ask/a11792.html

oscar1 · Dec 13, 2006

I somehow have the feeling that some day we will find that 'gravity' and 'time' are manifestations of one and the same thing. If we'd call both a 'force' for the sake of argument, we can see that when the 'gravity force' is stronger, the 'time force' is weaker, and visa versa.

What stops matter from exceeding the speed of light

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