This has bothered me for ages! (re: Travel faster than the speed of light)

Ok , this on the fly with what little I can remember and thus is operating on a few assumptions that may well be erroneous.Ok as you approach the speed of light your mass increases exponentially till at the speed of light your mass about infinite (pick any infinity you want) .We know that Sufficiently massive objects have a Schwarzschild-Radius beyond their physical bounds and thus no light can escape beyond the event horizon.Also sufficiently massive bodies will cause gravitational lesing of the objects on the far side of the at C craft: relative to the observer.So for a craft where it’s speed is >=C you wouldn’t see the ship at all, but an area of distorted space as if a huge fuzzy lens was stretched out through space.

Mass doesn't increase with velocity, only "perceived" mass. There is thus no increase in space-time curvature, and hence no gravitational effects.Also, just to be picky, it's not sufficient mass that reveals the Schwarzschild radius, it's density. You must contain all of your mass M within a radius 2MG/c^2.

Ok Cavediver, here is a question. I do not know a lot of physics.Is there such a thing as "perceived inertia" as there is of mass however conceived?I ask because in a Cambridge book "Modern Magnetism" they indicate what I believe was Maxwell's notion of inertia in magnets was not resolved until the 60s.This question is important because if gravity is more like inertia than force (and) I still see the possible existence of absolute space even rejecting an aether, biologically, I can not exclude the effects of "perceived mass" depending on the intelligence of the life so designed (whether by aliens or not etc) such that should biological light be symmetric across saidlight cone and design symmetric commensurably the effects of the code might "appear" to move faster than light but this would be appearence in Kant's sense strictly, even if the mass effect has more than inertial influence.Is there a confusion about inertia comparable to the one about mass at near light velocity? (I asked this because it seems theoretcially possible to have a long term supply curve that is horizontal with respect to the equivalent of price level ordinate to an independent increase in a population biology flush).This message has been edited by Brad McFall, 09-22-2005 03:59 PM

Hi Brad, yes there is definitely perceived inertia. In fact, it is precisely this "inertia" that leads to the idea of the mass increasing. For a given observed impulse, there is not the observed expected increase in velocity. This suggests that the inertia must be increasing, and hence the mass.

Hi Trixie.I'm not sure how much I can help, but your question sparked a memory of reading about this exact scenario (or, at least, a very similar one) many years ago in Paul Davies' About Time. So I dug it out and found the appropriate part, which I'll reproduce for you here. I realize this is slightly different to the question you asked, but it's pretty close so I thought I'd add it.Good question, by the way. This is something I've long wondered about, myself. It's nice to know I'm not the only one who ponders such things.Sorry I can't help you more, but perhaps cavediver or one of the other appropriately educated individuals here could expand on Davies' scenario a little, or give their own take on it.

See I told you I was probably talking botox

I'm grateful for the replies my wee thread gained. I'm also pleased to see that I'm not the only one who's wondered about things like this. Food for more thought, indeed. Ta.

Indeed. Sometimes I feel like such a dork... And then I see threads like this and realize that even if I am, at least I'm in good company.

To cut a long story short I've become an unofficial science advisor for a friend who has decided to write a sci-fi novel. From what I've seen so far, the concept he's got is excellent and I imagine it will produce sufficient interest to go on to publishing.Whilst reading through it, I commented that the ships were travelling faster than the speed of light...which raises some issues (how?). So I've been set the unenviable task of conceiving of a way of travelling FTL.My first instinct was wormholes, but for unimportant reasons that isn't an acceptable concept. My second idea turned out to be the same concept used in Star Trek and Dune, warping space in some manner. I was thinking of the apparant FTL travel of galaxies. The concept has been expanded on and is called Alcubierre’s "Warp Drive".This idea was OK, but its not very original and he wanted something a little different. Back to the drawing board for Mod. After several thoughts about getting over the inertia/mass increase problems my friend asked if it was possible to change the speed of light around the spaceship.I thought about it and decided that it might be an interesting idea, some kind of local field within which light speed is different. Knocking around the internet ended with me at this site in my investigations of the vacuum energy.Ignoring for the moment the difficulties in changing vacuum energy my first question is 'Would this work?' with the caveat that this is sci-fi so a bit of fudging will probably be necessary either way. It doesn't matter (for now) the hows of setting this field up, its more a question of 'If this field exists, would FTL be achievable'. I suppose it wouldn't be FTL really it would just be faster that 300,000kms^-1.Whilst thinking about this, I wondered what this would look like, and conceived of a strange stretched out line of a spaceship that started growing at the destination until it reached where the spaceship 'was'. I was gratified to see that this was at least partly right from reading this thread. Another idea was to have the whole craft distort space in such a manner as to appear effectively invisible (you'd see the distortion against the background of stars of course).There is an equation on the site linked above that I rearranged (I know of at least one mathematical blunder with it, there may be more but they are rendered unimportant by my first one), to give the following:

c = √(28πGρ)
------
( Λ )
​

Λ is the cosmological constant and ρ is the vacuum energy densitySo, by my reckoning the thing this bizarre drive should endevour to alter would be ρMy problem is that it might not make sense at all from what I've done. Thus my second question. I thought the point of this equation was to demonstrate the way in which Λ is proportional to ρ. So if ρ changed then Λ would have to also change, in such a way that would maintain c as is.I realized my error, and looked at the corrected equation:

c = √(28πGρΛ)
------
( Λ )
​

I thought this might a bit like saying 'all we have to do is change the energy to mass relationship and we can change c from e=mc². I also realized that this was coming from physics that was assuming homogenous vacuum energy density so I was probably going nowhere trying to figure it out.I thought that the vacuum energy density might hold the key, but I'm having difficulty finding out the relationship between ρ and c. My brain is starting to hurt now, so I'm going to watch a Horizon program on Brane theory to see if that will cure it. A little help from anyone who has more clue than me?

I lost you early on in Mod, but I have to say you write such well written posts with such frequency. Even if I can't follow it I can recognise its problem-descriptive attributes - which are excellently conveyed.ps: if its a sci-fi novel and it's going to make any money then the point is moot. Most readers won't need more than to be slightly boggled by the science to be able to enjoy it. This bit seems to hold the most potential for some expository (if scientifically inaccurate) prose "Of course" the tills will ring!This message has been edited by iano, 27-Apr-2006 01:08 AM

Hi Mod... it's late and I need sleep! So more later, but for now:Wormholes are best You can have DS9 natural, "stargate" manufactured, and the original and best: Contact type plucked from the quantum foam! Wormholes as we now know them were discovered by Misner and Thorne by the direct request of Sagan whilst he was writing Contact! Super-Science to order The AWD is almost as cool...Changing the speed of light doesn't really work too well. It doesn't actually make any sense for reasons that are hard to explain at this time of night. But when has sci-fi ever had to make sense? The AWD is probably the closest realistic version of this.I'll get back to you on your maths tomorrow.Just remember that any FTL is equivalent to time travel. You can't have one without the other. Sci-fi is of course free to dismiss this as it invariably does all the time...BTW, sci-fi is usually better not trying to describe its science. Dune is all the better for keeping everything semi mystical. As much as I love Donaldson's Gap Series, his attempts to explain the science had me weeping with frustration!

Wow, I didn't know that about wormholes - that's totally great. One of the reasons why wormholes are to be avoided is that they are already employed in book and we need to conceive of second method. Well, my thoughts exactly, and something that I brought up. I think if we are going to start conceiving of FTL we are going to have to take some liberties with reality somewhere. I advised that in the end we would need to compromise with science and fantasy but we'll have to do so in a way that doesn't suspend disbelief too much. Its bizarre for you to say that, but its almost a direct quote from my own lips when I was talking about it. Agreed. There are some notable exceptions. Sagan, is one obviously. The other is Alastair Reynolds, whose an astrophysicist. If you haven't read any of his stuff I advise you do. He goes to great pains to discuss the relativity issues, including one fantastic space chase at near the speed of light which is an entire chapter seemingly dedicated to the wierdness that goes with it. Agreed again. In the prequels, before space folding came about they still travelled FTL, but it stil meant they'd arrive months after they set off. In the prequels, it seems like they decided to ignore relativity entirely, and they don't suffer for it. I've not read them, but if I do, I'll try and take his science with the appropriate level of salt

It's a catchy idea (light speed bubble), that has a nice visual element to it (stretching spaceships).I think it's a winner even if you can't find a mathematical basis for it.

Thank you very much. Aye, call it a sense of perfectionism!

I'm calling intellectual property on ya! Hehe, I'll remember this conversation if any similar sounding drives come out in another sci-fi from Manchester (seriously though, how many of us are there on this board??)