What does light speed look like? An experiment.

[crysysone]

I wonder what it would look like to approach and exceed the speed of light. I try to imagine something like a sonic barrier but with photons except the analogy doesn't completely sync up.<br /><br />The idea is to put a camera on a platform and accelerate it to 50% of the speed of light. Then accelerate a target platform at 50% of the speed of light traveling toward the camera so that they 'buzz' each other. Realtively speaking, the camera would witness an object approach at the speed of light. No?<br /><br />If this works you can increase acceleration to see speeds in exccess of light speed, relatively breaking light speed.<br /><br />The only difference to actually getting up to a signifigant fraction of light is that each craft will experience much less than half the mass and time dilation effects of high speed travel. Would this affect the experiment and in what way?

 

[vogon13]

Your experiment has been simulated on a computer (sorry I don't have a link)<br /><br />They just used a ray tracing rendering program and modified it to allow the inputing of the appropriate value of c. (IIRC, most ray tracing software doesn't consider propogation delays)<br /><br />It turns out most of the bizarro visual effects one might anticipate are severely muted by the speed of light.<br /><br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[weeman]

Welcome to the SDC message board Crysysone!<br /><br />I understand what you're saying. I'm not sure if it would actually be possible to view something beyond the speed of light with this experiment. If the experiment were to take place, each platform would have to travel at about 93,000 miles per second (50% of the speed of light). So, with our technology, or most likely any technology in the future, we have no ways of accelerating platforms to this speed.<br /><br />Of course, I think you are just asking if it is theoretically possible to do this. I am sitting here trying to comprehend and visualize this type of experiment. If the combined speeds of the two platforms exceeds the speed of light, I'm not quite sure if there would still be any way to observe something faster than the speed of light.<br /><br />It does make me think of something kind of odd though. Lets say two cars get in a head on collision, each traveling at 60mph. This means that the combined force when they hit feels more like 120mph. So, if a car is traveling at 50% the speed of light, and the other is traveling at say 55%, does this mean the combined force that they hit at is faster than the speed of light?<br /><br />Just a strange thought that I was thinking from this post <img src="/images/icons/tongue.gif" /> <div class="Discussion_UserSignature"> <p> </p><p><strong><font color="#ff0000">Techies: We do it in the dark. </font></strong></p><p><font color="#0000ff"><strong>"Put your hand on a stove for a minute and it seems like an hour. Sit with that special girl for an hour and it seems like a minute. That's relativity.</strong><strong>" -Albert Einstein </strong></font></p> </div>

 

[crysysone]

Thanks for the Welcome!<br /><br />So if relativistic speeds don't add, what do they do? Could the effect of superluminal speed be seen if both platforms get to 70%? 80%? Or is timespace crunched so much that everything tapers off at those speeds. even if just realitive to another object? How does that work? That 'breakdown' at the edge of c is what I've never really been able to get right in my head.<br /><br />Those links are awesome, thanks. They seem to stop short of really delving into what I'm talking about though.

 

[weeman]

Thanks for the C-Ship link Eburacum, very interesting!<br /><br />So, we should essentially experience time dilation, right? Even though I am sitting still in my chair, I am still sitting on a planet that is orbiting, in an arm of the galaxy that is also rotating, and the galaxy is moving in one direction. So doesn't this mean that we experience the dilation to a certain degree? Do the clocks on Earth tick slower than a clock that would be in a completely stationary situation? (i.e. not moving in any direction in Space whatsoever) <div class="Discussion_UserSignature"> <p> </p><p><strong><font color="#ff0000">Techies: We do it in the dark. </font></strong></p><p><font color="#0000ff"><strong>"Put your hand on a stove for a minute and it seems like an hour. Sit with that special girl for an hour and it seems like a minute. That's relativity.</strong><strong>" -Albert Einstein </strong></font></p> </div>

 

[jaxtraw]

Everybody experiences time dilation from somebody else's point of view. In relativity there is no preferred "reference frame". This means if you're flying past me at half the speed of light, you have an equal "right" to say that you are stationary, and it's me that's flying past you at half the speed of light.<br /><br />This means that if I look at your clock, I will see that it's running slower than mine. But if you look at my clock you will see that it is running slower than yours! This seems rather paradoxical, because it's like saying that Alice is taller than Bob, and Bob is taller than Alice. But it's an essential part of Special Relativity- in fact, once you've accepted the fundamental thing about light, which is that everybody, whatever their speed, measures lightspeed to be the same, it's unavoidable.<br /><br />So anyway, there's no way to say who is stationary. It's all really very democratic. <img src="/images/icons/smile.gif" />

 

[lysol]

hey that movie sim is great but they forgot one thing....the red and blue shift.<br /><br />Light directly in front of you would shift blue and the light will visably shift red as you start to look to either side. And since your going fast as or faster than light the red shift will eventually turn to a pitch black behind you as the light cant keep up.

 

[docm]

It's not that the light behind you "can't keep up" it's that it redshifts into the infrared or radio spectrum where it's invisible to your eyes, hence it looks "black". <br /><br />Additionally the light coming from the front would blueshift into the x-ray and possibly gamma ray wavelengths. Also invisible to your eyes, until they're fried that is <img src="/images/icons/tongue.gif" /> <div class="Discussion_UserSignature"> </div>

 

[trumptor]

Hi everybody. I'm not an expert in physics as you will quickly learn, so sorry for the questions ahead of time. I don't understand the time dilation effects and never have. In those old commercials for some books or something they always would say if somebody travelled from the earth at near c they would travel to the nearest star and back in like 10 years or so and return to Earth and find everything to have aged a hundred years or whatever. My question is that if everything is relative, who's to say that it isn't the Earth receding from the observer at close to c? And why when the Earth returns isn't the observer 100 yrs older and the Earth only 10 yrs older?<br />Another question is as follows:<br />If it is possible to travel at 1/10th the speed of light, what if you launched a ship in space at this speed, then from it launched a smaller ship at 1/10th the speed of light from this ship...until you do this 10 times and eventually launch a ship the size of a grain of salt or so from the 10th ship. Relative to the original ship would this ship be breaking the speed of light barrier? And if we consider Earth as one ship, our solar system as another and our galaxy as another, isn't there a place out there in space somewhere that we may fall 100mph short of breaking the c barrier in relationship to? Then what happens if we get in a car and travel at 200mph in the opposite direction of the object? Why do we not go faster than c relative to this object and what is the speed then that we travel relative to it? <div class="Discussion_UserSignature"> <p><em><font color="#0000ff">______________</font></em></p><p><em><font color="#0000ff">Caution, I may not know what I'm talking about.</font></em></p> </div>

 

[SpeedFreek]

Those are very good questions! <img src="/images/icons/smile.gif" /><br /><br />Inertial frames of reference are the key here. According to special relativity, time dilation is indeed symmetrical between two <i> inertial </i> observers. If the spaceship is travelling at a constant speed away from earth, then you can consider that the earth is moving at a constant speed away from the spaceship. To the spaceship pilot, clocks on earth would look slowed down, and to observers on earth, the spaceship's clock would look slowed down by the same amount. So how could the spaceship pilot return to earth and find himself younger than his twin brother who stayed behind?<br /><br />Well it seems that time dilation is <i> not </i> symmetrical if one observer is not in an inertial frame of reference (i.e. whilst the spaceship is either accelerating or decelerating). It is tempting to think that the earth could be considered to be accelerating away from the spaceship as much as the spaceship accelerates away from the earth, but this is not the case.<br /><br />The earth is in an inertial frame of reference (simply put, the earths movement is inertial - it is in free fall around the sun at a constant speed, held in place by the suns gravity). But the spaceship's movement is not inertial when it is accelerating or decelerating - it is not moving at a constant speed.<br /><br />According to special relativity it is this difference in the nature of the spaceships motion that allows time dilation to cause such a paradox.<br /><br />As to your second question, it matters not whether you simply want to launch a ship the size of a grain of salt straight to the speed of light, or to do it in stages as you described. The closer you get to the speed of light the more energy you require to accelerate more. Anything with mass requires infinite energy to accelerate to the speed of light.<br /><br />And I'm hoping someone else will answer your last question about the relative speeds! I know that according to <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>

 

[trumptor]

"Vr=V1+V2/1+V1*V2" I do now remember a professor once telling me this formula vaguely and that it would ruin my great idea of faster than light travel. I do also think he said the mass would approach infinity as well for some reason. It seems so counter-intuitive. Good thing in 5th grade when 2 trains left a station at 25mph and 35mph it was still true that 35-25 equalled 10, lol. Thanks for the help.<br />Now considering that the acceleration was the culprit in time dialation is it true that during the trip away from Earth and the trip to Earth didn't affect time in any way while there was zero acceleration? Is it only during the acceleration that the dialation occurs? And I'd assume that decceleration would also have to have an effect on time. Why wouldn't this have an opposite effect from the acceleration and negate the overall effect? <div class="Discussion_UserSignature"> <p><em><font color="#0000ff">______________</font></em></p><p><em><font color="#0000ff">Caution, I may not know what I'm talking about.</font></em></p> </div>

 

[trumptor]

Thanks for the examples. I seem to be able to grasp how it all works mathematically. But its so counterintuitive to think that if an object is moving from Earth at .1c and another object is moving relative to the first one at .1c that it is retreating from Earth at .198c instead of .2c.<br />I guess I just don't like the fact that the c barrier implies we are basically stuck in our solar system unless we take some ridiculously long journey to another star system. Hopefully we'll be able to find a loophole like wormholes or something else. I guess we'll first have to stop our squabbles and environmental problems here on Earth before we can seriously consider those type of things, but eventually I think I would like to hope we will move on after the sun grows too hot for life to continue here. I think I'm getting off subject. Thanks for everybody's help. <div class="Discussion_UserSignature"> <p><em><font color="#0000ff">______________</font></em></p><p><em><font color="#0000ff">Caution, I may not know what I'm talking about.</font></em></p> </div>

 

[SpeedFreek]

<font color="yellow"> I guess I just don't like the fact that the c barrier implies we are basically stuck in our solar system unless we take some ridiculously long journey to another star system. Hopefully we'll be able to find a loophole like wormholes or something else. </font><br /><br />Well, if you actually consider the c barrier as the constraint, we have one loophole already - time dilation!<br /><br />Considering the speed of light as a barrier to our exploration of space implies you wish to go faster than the speed of light. But if you want to explore, then the speed of light isn't such a bad speed to travel at! <img src="/images/icons/wink.gif" /><br /><br />Although travelling <b> at </b> the speed of light is theoretically impossible, if you could do it you would reach your destination instantly, due to time dilation. It is only the people you leave behind who watch you crawl towards the stars at the speed of light.<br /><br />But if actual light speed travel is impossible, lets consider travelling at just below the speed of light (my favorite subject!).<br /><br />If you want to travel 5 light years, at 0.999c the journey would take you just 81 days. To everyone else, it would look like it took you over 5 years! If you came straight back, you would have aged under 6 months, but everyone back home would be over 10 years older. If you made the 5 light year journey at 0.9999c, it would take 25 days. At 0.99999c, it takes just over 8 days!<br /><br />It does take enormous amounts of energy to travel at these speeds, but theoretically it's not impossible. <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>

 

[weeman]

I think you're right Speedfreak, if we ever want to achieve interstellar travel, it will have to be at speeds that are fractions less than the actual speed of light. <br /><br />The idea that I am having trouble with, is how it would be possible to go anywhere if we could actually travel at the speed of light. Time stops at the speed of light, correct? So how is it possible to do anything if time is not moving? Just to walk across my living room takes time. I'm getting a dilemma because I can also understand how the trip would be instantaneous to a traveler who is traveling at the speed of light.<br /><br />If we are ever able to find the required energy to boost a ship to 0.9999c, it would forever change the fate of the human race. Might it be possible within our existence? Maybe in the next 200-300 years? As long as we don't kill eachother off in a massive world war, or a cataclysmic event takes place that wipes out life from this planet. <img src="/images/icons/rolleyes.gif" /><br /><br />If a group of people were to leave Earth in search of other habitable planets, they would pretty much have to say goodbye to their loved ones. If their journey only takes them a few years total to find other planets (or other civilizations), it means that vast amounts of time would have passed on Earth. I guess it's kinda sad to think about, but it would also lead to the most incredible discoveries in the history of Mankind. <div class="Discussion_UserSignature"> <p> </p><p><strong><font color="#ff0000">Techies: We do it in the dark. </font></strong></p><p><font color="#0000ff"><strong>"Put your hand on a stove for a minute and it seems like an hour. Sit with that special girl for an hour and it seems like a minute. That's relativity.</strong><strong>" -Albert Einstein </strong></font></p> </div>

 

[weeman]

I think I have solved my own dilemma that I stated in my post above this one <img src="/images/icons/smile.gif" /><br /><br />I was wondering how it is possible to do anything if time is stopped (traveling at the speed of light). However, I got to thinking, it takes time for any processes to happen in the Universe. Just for me to think of a sentence in my head, it takes a certain amount of time. In other words, our own thought processes in our brains take some amount of time. So, if time stops when the speed of light is reached, then any thought processes stop. <br /><br />Lets say I am in a ship that is traveling less than the speed of light, when the ship accelerates to the speed of light, the thought processes in my brain will seise. So when the ship slows down to a speed slower than the speed of light, time starts to tick again. <br /><br />So in other words, I will not be able to perceive the period of time when the ship is traveling at the speed of light. This is what makes the trip appear to be instantaneous. <br /><br />The Milky Way is 100,000 lightyears across. If I hopped in my ship, and started at one end of the Milky Way galaxy, I could make an instantaneous trip to the other side, if I travel at the speed of light. It would be kind of an odd trip. If I hit the thrusters to boost me to lightspeed, it would seem as if nothing happened because the trip was instantaneous. I might think the ship didn't go anywhere, yet when I look out the window, I realize that I am now on the opposite side of the galaxy!<br /><br />Unfortunately, everyone I know and love on Earth will be long gone, because 100,000 years would have passed on Earth.<br /><br /> <div class="Discussion_UserSignature"> <p> </p><p><strong><font color="#ff0000">Techies: We do it in the dark. </font></strong></p><p><font color="#0000ff"><strong>"Put your hand on a stove for a minute and it seems like an hour. Sit with that special girl for an hour and it seems like a minute. That's relativity.</strong><strong>" -Albert Einstein </strong></font></p> </div>

 

[nova_explored]

also, don't forget, in order to slow down requires the same input energy as to speed up. If you could in fact reach that barrier, C, which is infinite, you would also require an infinite amount of energy to slow down.<br /><br /> <div class="Discussion_UserSignature"> </div>

 

[alokmohan]

C is infinite.

 

[weeman]

Right, the idea of speeding up and slowing down is merely a theoretical situation to explain how traveling at lightspeed is instantaneous. To the best of our knowledge of physics today, it is impossible to actually travel at the speed of light. Even if it were possible, wouldn't it be a very dangerous way to travel? If you are unable to do anything while the ship is traveling at the speed of light, wouldn't you basically be flying blind?<br /><br /> <div class="Discussion_UserSignature"> <p> </p><p><strong><font color="#ff0000">Techies: We do it in the dark. </font></strong></p><p><font color="#0000ff"><strong>"Put your hand on a stove for a minute and it seems like an hour. Sit with that special girl for an hour and it seems like a minute. That's relativity.</strong><strong>" -Albert Einstein </strong></font></p> </div>

 

[SpeedFreek]

Yes, and at lightspeed you also wouldn't be able to stop. Not just because of the infinite energy scenario, but also because there is no time passing for you to press the button, or the computer to issue the order to stop.<br /><br />If an object travelling at c is effectively frozen in time, how can that object initiate any process to make itself slow down again? Any process takes time, but time isn't moving inside the object. The pilot would be frozen, the computer would be frozen, no atoms would be vibrating.<br /><br />So maybe only an external force could instigate the braking process. But that could not be done by transmission, as the signal would never reach the ship, and even if it did the computers arent moving data, the antenna on the ship wouldn't have any time in which to transmit the data. In fact the antenna wouldn't have any time to receive the transmission.<br /><br />Or maybe, if you put a giant OFF button on the outside of the spaceship, someone could reach out and slap it as the ship shot past at the speed of light? <img src="/images/icons/wink.gif" /> <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>

 

[MeteorWayne]

That's why they call it Ludicrous Speed. <img src="/images/icons/laugh.gif" /><br /><br />"Smoke 'em if you got 'em" <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[why06]

So when this happens this is virtually a sonic boom for space-time.<br />Space-time builds up in front of the craft because of the energy of the craft pushing up against it, but eventually it reches a point where space- time cannot interact with it any more. just lke eventually air built up infront of a jet is no longer reacting to the jets movements fast enough and so a sonic boom is heard asthe speed of sound is broken.<br /><br /><font color="yellow">Questions?<br /><font color="white"><br />Why though would Space need to have a speed?<br /><br />And what would happen?<br />-would time stop reacting to the ship vibrations?<br /><br />And is this scenario be anything like the way light moves?<br />-Would the ship even be matter anymore or just energy, because shouldn't the ship's on atoms which can only exist in the speed of space-time stop reacting with themselves?<br /><br /><br /><font color="yellow">Conclusion:<br /><font color="white">To me it seems like the only way for the matter to continue existing is as energy. <font color="yellow">So maybe its not space-time that has a speed limit, but matter? <br /><br /></font></font></font></font></font> <div class="Discussion_UserSignature"> <div>________________________________________ <br /></div><div><ul><li><font color="#008000"><em>your move...</em></font></li></ul></div> </div>

 

[weeman]

hahaha, ludicrous speed! Good reply Wayne <img src="/images/icons/smile.gif" /><br /><br />"no no, lightspeed is too slow."<br /><br />"sir, lightspeed too slow?"<br /><br />"yes. we'll have to go straight to ludicrous speed!"<br /><br />Anyways, in reply to you Why06, I'm not sure if I have ever read anything about a "sonic boom" for breaking the speed of light. As you state it, I suppose it is possible that something like this takes place. Of course, would it be in the form of a boom? Or might it be something else? <br /><br />The properties to create a sonic boom deal with the finite speed of sound, and the fact that their is air in the atmosphere. However, with the speed of light, we are dealing with something that is seemingly infinite (C), and if we were to reach this barrier, it would be done in Space (a vacuum).<br /><br />So, rather than a sonic boom, what might be the events that a person could theoretically witness from watching a ship break the speed of light? <div class="Discussion_UserSignature"> <p> </p><p><strong><font color="#ff0000">Techies: We do it in the dark. </font></strong></p><p><font color="#0000ff"><strong>"Put your hand on a stove for a minute and it seems like an hour. Sit with that special girl for an hour and it seems like a minute. That's relativity.</strong><strong>" -Albert Einstein </strong></font></p> </div>

 

[jaxtraw]

Cerenkov radiation is a kind of "sonic boom" for light. It's possible when light is travelling through a medium such as water- in which light travels slower than the speed of light. Light only travels at c in a pure vacuum. Even in air, it's slightly slower.

 

[danieloneil01]

hahaha, ludicrous speed! Good reply Wayne <br /><br />"no no, lightspeed is too slow." <br /><br />"sir, lightspeed too slow?" <br /><br />"yes. we'll have to go straight to ludicrous speed!"<br /><br />_______________________________________________<br /><br /><br />LOL, is that from the greatest Space movie of all time? Spaceballs?

 

[weeman]

Indeed it is from Spaceballs.<br /><br /><br /><br /> <div class="Discussion_UserSignature"> <p> </p><p><strong><font color="#ff0000">Techies: We do it in the dark. </font></strong></p><p><font color="#0000ff"><strong>"Put your hand on a stove for a minute and it seems like an hour. Sit with that special girl for an hour and it seems like a minute. That's relativity.</strong><strong>" -Albert Einstein </strong></font></p> </div>