48 replies to this topic

[Infernity]

Was thinking on it again when my little sister asked me how much is 1 minus 5.
I used beads to demonstrate for the other questions, but how can I explain her minus?
I tried to use different colours, but she messed everything up, so I gave up and told her that it is impossible to subtract a number from a lower number.
I was thinking how to show her minus, maybe a mirror?, but quickly got off the idea.
I started thinking how to make something not disappear and become zero, but become- minus, and came up to black holes.
I was thinking what happens, where does everything just vanish?
Can the swallowed elements by black holes appear in another dimension? Is it possible that there is a matching opposite universe that actually everything that happens here is the spilled by contrasting 'white projection' there?
May the universe work like that? Have such balance?

Yours
~Infernity

[eternaltraveler]

The stuff that falls into a black hole is still there. It's just smashed down into a singularity. It's mass is still felt. Although modern physics still has trouble with saying exactly what is happening at the center of the black hole. It is however very unlikely that it ends up in another universe.

Now as far as explaining it to your sister. When you add 1 and -1 you get 0. Nothing. -1+1 is the same as 1-1. Parallels in nature can be hard to see easily. Almost impossible to demonstrate with physical objects. Only if you had a negative bead (composed of negative energy) put together with your positive bead the result would be nothing, zero. However you can demonstrate with other concepts other than physical matter.

If you have a rocket that accelerates upward at exactly the force of gravity it will go nowhere. That's because the force of gravity, plus the force of the rocket equal zero.

[Infernity]

My little sister Elrond, do not understand what's minus yet. So if I tell her -1+1 she still will have no idea what I'm talking about. She's in the kindergarten. It doesn't matter if the minus sets in the result or as an element in the exercise...

Now again to the black holes- do you mean the items find themselves in another universe somewhere else or simply are so small to have the ability to be set on a little universe whom seems to us as a piece of energy?

If the first option- than I turn back to my first point... of maybe the other universe is complete opposite.

If you have a rocket that accelerates upward at exactly the force of gravity it will go nowhere. That's because the force of gravity, plus the force of the rocket equal zero.

Sure, as if we fly against the spinning direction of the earth but slower than the spinning speed- we'll move backwards on the globe, and same speed means- staying at the same place...

Yours truthfully
~Infernity

[armrha]

Was thinking on it again when my little sister asked me how much is 1 minus 5.
I used beads to demonstrate for the other questions, but how can I explain her minus?
I tried to use different colours, but she messed everything up, so I gave up and told her that it is impossible to subtract a number from a lower number.
I was thinking how to show her minus, maybe a mirror?, but quickly got off the idea.
I started thinking how to make something not disappear and become zero, but become- minus, and came up to black holes.
I was thinking what happens, where does everything just vanish?
Can the swallowed elements by black holes appear in another dimension? Is it possible that there is a matching opposite universe that actually everything that happens here is the spilled by contrasting 'white projection' there?
May the universe work like that? Have such balance?

Yours
~Infernity

Well, it's hard to exactly pinpoint what would happen to material travelling near a black hole. The first and most important thing is that the information that falls into a black hole, at least by information theory, is totally lost to this universe. It's light cone is destroyed. In this way, tossing something into a black hole is kind of like subtracting it from the universe; If we tossed you into the black hole, and there was no means in snatching your brain configuration as you hit the event horizon, you would be lost forever inside it (provided you didn't discover a way to travel faster then light...). While they think black holes to decay in a steady release of energy over time, the decay is information-free, pure entropy, a sine wave of hawking radiation, and it doesn't escape from inside the event horizon, just right on the edge.

The concept of a white hole, or the opposite of a black hole, is only mathematically possibly with a zero-mass black hole, which we don't currently think can exist. Otherwise, the event horizon will stop any matter from escaping: Say you are on a vector for the exit of the black hole, once you passed through the event horizon you might come close to where that 'white hole' would be, but the event horizon from the massive black hole would keep you from ever actually escaping. Otherwise, all black holes would constantly be ejecting their matter and things like time travel would be very simple affairs. I don't know why the ejected white hole would be in another dimension.

I suppose you've already thought, 'But what if we discover matter with negative mass/inertia?'. Well, that poses another problem too. If we thread the black hole with exotic matter like that, when the white hole was formed it would eject the entire contents of the gigantic star that created the black hole nigh instanteously. That's not circumventable, just hazardous, though...

Anyways, if there were common naturally occuring white holes I'd think we'd see them by now... they'd be a lot brighter then black holes.

[Infernity]

You made me think a lot Armrha.
I am rejoiced to say that I seem to find you understand me pretty much a lot, our lines of thinking are somewhat alike; that's great to to have you here. I'd like to someday discuss these things with in you person.

Well, it's hard to exactly pinpoint what would happen to material travelling near a black hole. The first and most important thing is that the information that falls into a black hole, at least by information theory, is totally lost to this universe. It's light cone is destroyed. In this way, tossing something into a black hole is kind of like subtracting it from the universe; If we tossed you into the black hole, and there was no means in snatching your brain configuration as you hit the event horizon, you would be lost forever inside it (provided you didn't discover a way to travel faster then light...). While they think black holes to decay in a steady release of energy over time, the decay is information-free, pure entropy, a sine wave of hawking radiation, and it doesn't escape from inside the event horizon, just right on the edge.

Hmm when uploading will be possible, it will be possible to totally destroy information then. Lose secretes which never meant to be exposed to what seems as forever. Will we reach it by living that long?

Oh, our humanistic mind, so sophisticated and such thinkers we are here, but so limited... No place to store infinity... So weak.

The concept of a white hole, or the opposite of a black hole, is only mathematically possibly with a zero-mass black hole, which we don't currently think can exist. Otherwise, the event horizon will stop any matter from escaping: Say you are on a vector for the exit of the black hole, once you passed through the event horizon you might come close to where that 'white hole' would be, but the event horizon from the massive black hole would keep you from ever actually escaping. Otherwise, all black holes would constantly be ejecting their matter and things like time travel would be very simple affairs. I don't know why the ejected white hole would be in another dimension.

The white thing won't be termed as a hole since it won't swallow but spit.
Now, it will be in another dimension just for making it easier for us... I mean-

Anyways, if there were common naturally occuring white holes I'd think we'd see them by now... they'd be a lot brighter then black holes.

That's why we wouldn't see it... We are IN IT. We are the things that the 'white projection' has thrashed out...

I suppose you've already thought, 'But what if we discover matter with negative mass/inertia?'. Well, that poses another problem too.

Yes I did, and damn, so many unknown things heh.

Hmm so if the white projection has somewhat base of truth, then the only way to make something totally disappear is to somehow merge the two when the contrasting power is larger- fitting perfectly to have a surplus which matching oppositely the element whom meant to destruction.
In such case the overload from both side will be too big and won't transfigure to one opposite information. The problem is to count perfectly the mass and form. We'll need an extremely sensitive scanners- without limitations at all. Which will be not possible practically vanish something, but just encrypt, hide, change. Although theoretically it is possible.

Yours truthfully
~Infernity

[eternaltraveler]

While they think black holes to decay in a steady release of energy over time, the decay is information-free, pure entropy, a sine wave of hawking radiation, and it doesn't escape from inside the event horizon, just right on the edge.

I think hawking decided that information can survive. I'm not sure if he published the math that made him come to this conclusion yet.

Anyways, if there were common naturally occurring white holes I'd think we'd see them by now... they'd be a lot brighter then black holes

We wouldn't necessarily easily find a white hole, if by white hole you mean a negative energy black hole. They would emit no more radiation than a black hole does, and they would naturally repel from any ordinary mass. And therefore be in the voids between galaxies where it isn't easy to find them through their influence on stuff around them.

[Infernity]

Elrond,
You didn't get my idea of the opposite of the black hole...

I was thinking maybe a black hole is simply a way to thrash things to another dimension, where everything is the exact OPPOSITE, so there, the opposite of black hole is a "white ejector" where it is actually thrashing everything to our dimension, e.g light...

The only way to make energy (information) vanish is when it has the exact power from both dimensions + the extra power matches in the exact opposite the element whom meant to be destroyed.

Id est, something mass of +X *scale* (or whatever criterion) will be destroyed only if will be among infinite negative power of black holes and infinite positive power by the white ejector -X. (So the negative power should be bigger then the positive in X *scale*)

Let 'n' be negativity/negative.
Let 'p' be positivity/positive.
Let 'i' be infinity/infinite.
Let 'e' be energy.
Hence,
Xpe+in+ip+Xne=0
IOW
-Xe-i+i+Xe=0

The problem is to make "infinities" the same exactly but opposed.

Yikes I messed up... read my earlier posts here. :\

Yours truthfully
~Infernity

Edited by infernity, 17 May 2005 - 03:12 PM.

[armrha]

Blink.

This topic has been successful derailed. Inf, Susma... Can you take it outside? ; )

Anyways, on the topic of black holes, today I was thinking of spinning black holes. I know that we can use the mass of large planets to gravity assist probes going around, shooting a probe in the trailing orbit behind jupiter to speed it up or in front of the orbit of jupiter (and reverse to the spin) to slow it down. I know this also imparts energy on the probe and on the planet, with the energy moving from planet to probe or probe to planet depending on where we target it.

Thinking about a black hole, I realized that a gravity assist must effect light around a black hole as well. Light going around a spinning black hole the way opposite of it's spin should lose energy; it can't lose kinetic energy, so it must decrease in wavelength. Alternatively, going around the same direction as the spin should increase the net energy of the light.

So the interesting part is, we could effectively increase the spin of a black hole without having to interface with it much. If we had a giant laser, we could send light on a very close, energy-losing orbit with the black hole, and increase the black hole's spin. What happens if we increase the black holes spin to the point of where all the matter in the black hole is held in a ring around the event horizon, rather then the center? (since it can't really fly apart...)

This could be used as a kind of advanced battery. The output of a whole star could be channeled into a laser or the like, which could spin around a black hole to charge it up. The black hole could then have a laser spin the other way around it to absorb the energy back out of the black hole, getting a gravity assist from it. As far as I know, this doesn't break any rules of physics. Am I missing something? This seems pretty cool.

[Infernity]

(edited, among...)

Armrha! that's brilliant!
I have many times dialogs with my dad about these stuff, and he used to claim we won't be able to travel in the space too far, because an infinite energy should be provided, because even if we would be able to travel in the speed of light- the universe has differences of billions light-years from places to some.
And moreover- he believed that for moving as fast as light we simply need and infinite energy sourse...

However, I said we can transfer ourselves as an energy, information... By upgrading ourselves into programmatic energy (info.), we can send ourselves as fast as maybe light, all we have to do is to exchange the energy called us in light elements, with same composition- transfer and exchange again, to something concrete.

But, black hole's spin- if that's only increasing, and not ending- that's a great source of energy production! Maybe we could stay as a concrete essential substance!

If you missed something- I believe I missed it...

Yours truthfully
~Infernity

Edited by infernity, 17 May 2005 - 03:15 PM.

[armrha]

That'd be wonderful, to be able to maser ourselves across the galaxy (we'd need a very powerful one!). But someone would still have to go there physically and set up an array to recieve us.

Black holes do end eventually too. I wonder a few things now that I look into it a bit more. I can't do the math to save my life, but it seems someone might have done it already: Looking into Kerr-Newman black holes. I'm curious if it would be possible to spin a black hole so much and compress so much of the singularity's matter against the event horizon. What is really bizarre is that if all that matter was compressed into a ring around the event horizon... it seems someone inside the ring would not feel any gravity at all. Maybe I'm incorrect, but isn't the net gravitional pull of any object in it's center zero? And if there were no matter there, no singularity to crush us to bits, there would be no danger... truly bizarre territory.



Sorry armrha about taking out the last paragraph. Is it is no longer relevant to this thread, which has now entered a parallel reality of the multiverse. I will save it with the rest of the posts that it relates to that have now been split off into the bizarro universe of the catcher. I call it the The Informational Tangent Deflector for Black Hole Theory.

To think what it really means is just a lot of extra work. [lol]

LL

Edited by Lazarus Long, 17 May 2005 - 06:38 PM.

[Infernity]

Note: Alright pals, this will be the last off topic post in this thread, it is just for those who get to see this for the first time and about to start talking about my sister again or any other thingy that has nothing to do with the general idea of the topic - - here is the place!

~Infernity

Edited by infernity, 17 May 2005 - 06:46 PM.

[Infernity]

(relevant part from removed post)

That'd be wonderful, to be able to maser ourselves across the galaxy (we'd need a very powerful one!). But someone would still have to go there physically and set up an array to recieve us.

Black holes do end eventually too. I wonder a few things now that I look into it a bit more. I can't do the math to save my life, but it seems someone might have done it already: Looking into Kerr-Newman black holes. I'm curious if it would be possible to spin a black hole so much and compress so much of the singularity's matter against the event horizon. What is really bizarre is that if all that matter was compressed into a ring around the event horizon... it seems someone inside the ring would not feel any gravity at all. Maybe I'm incorrect, but isn't the net gravitional pull of any object in it's center zero? And if there were no matter there, no singularity to crush us to bits, there would be no danger... truly bizarre territory

I love the way you think Armrha, aye it is weired.
About the someone who'll have to set there the thingy, I think we should let our creations- robots do it.
The shall get there as information to a supposedly safe point, then we'll define them as concrete, so they can do the wok done.

Hmm researching black holes could be interesting.
And turning the danger into a benefit could be awesome.

~Infernity

[eternaltraveler]

This could be used as a kind of advanced battery. The output of a whole star could be channeled into a laser or the like, which could spin around a black hole to charge it up. The black hole could then have a laser spin the other way around it to absorb the energy back out of the black hole, getting a gravity assist from it. As far as I know, this doesn't break any rules of physics. Am I missing something? This seems pretty cool.

It's very possible to harness that portion of a black hole's mass that is tied up in it's rotational kinetic energy using mechanisms you explained here. However you couldn't get more than that portion of it's mass. Remember, when you are using your laser beam to impart spin onto the black hole what you are essentially doing is converting the lost energy of these photons to rotational energy of the black hole (which also accounts for a portion of it's mass).

It would work as a battery for storing energy, yes, but I'm sure their are better ways to store energy. If you want to store the energy for a whole star as in this example it would probably be more efficient to put the star out and save the hydrogen for later. There is of course no reason not to use the rotational energy in a black hole that is already spinning.

[eternaltraveler]

I have many times dialogs with my dad about these stuff, and he used to claim we won't be able to travel in the space too far, because an infinite energy should be provided, because even if we would be able to travel in the speed of light- the universe has differences of billions light-years from places to some.
And moreover- he believed that for moving as fast as light we simply need and infinite energy sourse...

Infernity, you should talk to your dad about the effects of time dialation. Sure, as far as we know, mass cannot go faster than the speed of light (and reaching the speed of light would take infinite energy). However the effects of time dialation put a whole new spin on this.

For example, if you got into a spaceship, and accelerated at one g (1 times the force of gravity so it always feels just like on earth) for 20 years, and then turned the ship around and decelerated at one g for another 20 years, you would have traveled on the order of 2 billion light years (a good chunk of the way across the known universe). For you only 40 years have passed, but for the rest of the universe just a tad over 2 billion years have passed.

As you approach the speed of light time slows down.

There is no reason something like a ramjet wouldn't allow you to do just that. You'd neve be able to carry enough fuel to have the engines on at 1 g for 40 years straight, but there is plenty of fuel already floating around out there in the form of hydrogen. As your velocity increases the relative density of the hydrogen would increase. The hydrogen could be used to power a fusion engine. You just need to carry enough fuel to get the ship going fast enough so that the relative density of the intrastellar hydrogen is high enough for the engines to work, by the time you got out of the galaxy you should be going fast enough so even the tenuous hydrogen in the voids between galaxies is enough to power your engine.

[Infernity]

Well said Elrond thanks, I tried to explain here before, but you do it better )

We both do know it. (Me and my dad). Well said tho.

Yours truthfully
~Infernity

[Lazarus Long]

For example, if you got into a spaceship, and accelerated at one g (1 times the force of gravity so it always feels just like on earth) for 20 years, and then turned the ship around and decelerated at one g for another 20 years, you would have traveled on the order of 2 billion light years (a good chunk of the way across the known universe). For you only 40 years have passed, but for the rest of the universe just a tad over 2 billion years have passed.

Elrond I suggest that you go back and look at the math and other aspects of time dilation. I think we have a thread somewhere with the formulas.

In your example you would not have even traveled 40 light years. That is because you are possibly confusing aspects of the dilation effect and the ship has never actually exceeded *C*.

Even at the significant percentages of C that you are traveling the distances would be measured relative to the CRAFT not the observers that would experience a far longer period of time.

In the examples you gave it may be possible to reach the star systems that are nearest to Earth however but the temporal displacement is impossible to overcome according to GRT without resorting to wormhole aspects of other theories.

BTW I do not think the dilation effect at one G is as significant as you suggest until the velocity is within say 70% to 99% of C. I also think that it is easy to confuse the aspects you have because you are traveling for Y>X where Y represents the extra number of years relative to the Earth bound observer's X time elapsed but the distance traveled for the ship can still only be measured as d=vt for the craft's perspective where t for that equation equals Y, not X.

Edited by Lazarus Long, 18 May 2005 - 12:26 AM.

[Lazarus Long]

Here it is:
time dilation problem
http://www.imminst.o...T&f=9&t=5992&s=

By the way it is the experience of time that is the interesting aspect of this element of relativity.

It isn't really that time changes, however there are some supercollider and particle accelerator studies that appear to support the existence of the phenomenon.

Basically onboard time slows down relative to the outside observer the higher the velocity of the craft is relative to C. This doesn't alter the other aspects of time/distance relationship however because to do so would that suggest you are traveling faster than light with respect to onboard time and that is not what occurs according to GR.

[eternaltraveler]

Lazarus,

My math, though not terribly accurate to lots of significant figures, is accurate in terms of this discussion. The actual number would be approximately 42 years.

I first saw this example when I read "black holes and time warps" by Kip thorne in junior high.

This example really hammers home just how funky relativity and special relativity are. All you have to do is accelerate at g and you can cross the known universe in a normal human lifetime.

Basically onboard time slows down relative to the outside observer the higher the velocity of the craft is relative to C. This doesn't alter the other aspects of time distance relationship however because to do so would that suggest you are traveling faster than light with respect to onboard time and that is not what occurs according to GR.

You are absolutely right. You would not travel faster than light with respect to onboard time. The distance would compress. The person moving in this vessel would travel a shorter distance given by the equation x`=(x-ut)/sqrt(1-u^2/c^2). Where x is within the system, and x` is based on an observer in another system moving relative to x with a constant velocity u. t=time, and c=the speed of light. The lorenz transformation for time is t`=(t-ux/c^2)/sqrt(1-u^2/c^2).

You forgot about length contraction that's all.

Interestingly enough the distance the ship would travel IS less than 42 light-years relative to itself. 2 billion light years would be compressed into that small span. Which is a big reason why a ramjet would work so well. The relative density of the tenuous hydrogen in the voids between galaxies would be multiplied by an average factor of 50 million. And keep in mind that it would be moving through this 50 million times greater hydrogen at incredible speed even in it's own reference frame.

Edit: I lost the first half of this message when fixing a typo. Rewrote approximately.

Edited by elrond, 18 May 2005 - 12:47 AM.

[Lazarus Long]

However there is a great difference between 42, which I am still suspect of but won't argue about till I do the math for myself and

you would have traveled on the order of 2 billion light years

which is what you first said above. )

[eternaltraveler]

However there is a great difference between 42, which I am still suspect of but won't argue about till I do the math for myself and
QUOTE 
you would have traveled on the order of 2 billion light years 


which is what you first said above. 

I should have specified which reference frame the 2 billion light years was in. You got me )

[eternaltraveler]

also keep in mind that u in the above equation is for a fixed velocity. I don't remember if the average velocity will be accurate with the lorenz transformation.

[Lazarus Long]

Basically you are suggesting a 32ft per second squared constant acceleration rate or a rate that translates into a velocity that is far below light speed for the first period and then as it approaches C requires so much more energy that it passes a point of diminishing returns for acceleration to a velocity still well below 99% C for most of the proposed energy sources we can currently imagine including matter/antimatter conversion. ZPE is a separate issue [lol].

This generally mimics the problem of lifting a mass into orbit as the energy requirements for lifting the fuel alone are almost 85% of the fuel capacity of the rocket. Obviously these are apples and oranges but the issue is the same as the amount of energy to go from 80% to 90% C is equivalent to a major percentage of all the energy expended to reach 80% C that is why the formula achieves a demand for infinite energy to reach C. (The math is not done for this example)

However for the sake of argument do the math on that acceleration rate and you will find it isn't much faster in some respects than an elevator. )

From a stationary starting point, after the first hour you are still only doing just a little over the speed of sound at roughly 698 mph. However at this rate you will achieve escape velocity in roughly a little over a day but for the sake of argument lets begin from escape velocity but are you also seeing the problem?

The relationship to temporal dilation is loaded toward the higher velocities according to the Lorenz transformation and it will require a constant acceleration rate of one gee for almost two years to get even close to C.

I still approve of the method, don't get me wrong but there is a lot more going on than you related at first and this doesn't even go toward trying to *astrogate* the time dilation effect so that when you actually get to where/when you have been traveling you are actually where/when you want to be. )

Don't you just love the syntax of space/time? [tung]

And yes this relates to what I am saying.

also keep in mind that u in the above equation is for a fixed velocity. I don't remember if the average velocity will be accurate with the lorenz transformation.

In fact I believe it is even more complicated than averaging the velocities in order to apply the transformation and that is why I didn't think the result is actually 42 ly's either but considerably less. However it is enough velocity to get to the nearer systems including a few Earth types but round trips are not probably in the cards and assuming humans survive and achieve warp drive people that left later might get to the destination even before the first travelers.

Examples of mission targets:

Alpha Centuri A 4.3 ly
http://www.gsfc.nasa...02/20021011.htm

Sirius 8.6 ly
http://www.astro.uiu...sow/sirius.html

26 nearest stars
http://www.astro.wis...ra/nearest.html

Edited by Lazarus Long, 18 May 2005 - 12:47 PM.

[Lazarus Long]

Here is what you were referring to elrond, it is called the Lorentz Contraction

Time expands, space contracts.

Interestingly, while time expands from the perspective of the stationary observer, space contracts from the perspective of the moving observer. This phenomenon is known as Lorentz contraction, which is exactly the reciprocal of the above time dilation formula: l'=l*sqr(1-v²/c²). Thus the space traveler passing by Earth at a speed of 0.99c would see it's shape as an ellipsis with the axis parallel to his flight direction contracted to a seventh of its original diameter. That is of course, if he sees it at all, given the enormous speed. Therefore, space travel is shortened with the velocity of the traveler. A journey to the 4.3 light-years distant Alpha Centauri C, the closest star to our Sun, would take only 7.4 months in a space ship moving at 0.99c.

The effect of time dilation has been experimentally confirmed thanks to very precise cesium clocks that can measure extremely small periods of time. Unfortunately, time dilation is completely outside of human experience, because we have not yet devised a way of traveling at speeds where relativistic effects come into play. Even if you spent your whole life in a jet plane that moves at supersonic speed, you would barely win a second over your contemporaries on the ground. And, not even today's astronauts can perceive the Lorentz contraction. Imagine you are a cosmonaut on board of space station Mir, moving at 7700 meters per second relative to Earth. Looking down upon Europe from space, you would see the entire 270 kilometer east to west extent of Switzerland contracted by a mere 0.08 millimeters.

And if you look at this graph of the temporal dilation effect you will notice the problem with respect to velocity.

Time in the moving system will be observed by a stationary observer to be running slower by the factor t':

As it can be seen from the above function, the effect of time dilation is negligible for common speeds, such as that of a car or even a jet plane, but it increases dramatically when one gets close to the speed of light. Very close to c, time virtually stands still for the outside observer.

All from this nice concise page.

Time Dilation
http://www.thebigvie...medilation.html

http://media.nasaexp...-060/9-12_2.pdf
Twin Paradox (source NASA)
Consider two twins 25 years old. One twin steps on a space ship and travels through space at 0.95c for 4 years according to her. How old is each twin when she returns?

ans. 29 (traveling) and 37.8 (Earth) years old

Some basic physics for GR Space/Time and Black Holes
http://www.thebigvie.../spacetime.html

[Lazarus Long]

Now as I have been considering this problem it has also occurred to me that we are measuring on board gravity as a function of time (acceleration) and distance and these too will be effected by the Lorentz transformation and contraction hence the energy requirements to maintain one gee will not be constant but will probably increase hyperbolically paralleling the dilation curve.

This is only one of the reasons I was criticizing the assumptions on energy use but also why the variables associated with astrogating a constant, let alone uneven acceleration to near C make my head spin when I try and integrate them all into one set of calculations for even trying to reach Rigil Kentaurus (Alpha Centauri A) let alone the next nearest G type star system at over 40 light years away. [wis]

Not to mention that as velocity approaches c the density of the mass on board the ship approaches infinite according to some interpretations of the Lorentz contraction and this would mimic the relationship of proximity to a Black Hole.

[armrha]

Now as I have been considering this problem it has also occurred to me that we are measuring on board gravity as a function of time (acceleration) and distance and these too will be effected by the Lorentz transformation and contraction hence the energy requirements to maintain one gee will not be constant but will probably increase hyperbolically paralleling the dilation curve.

I don't think this is right. The effect of the acceleration is something measured from your frame of reference. The reason a lorentz transformation happens to the space around the ship is that the space around the ship is moving at the speed of light, while they are 'stationary' from their frame of reference. The acceleration effects, mass of the fuel and the mass of the ship, would all be acceleratad and not appear to gain any mass. In fact, they shouldn't measure any 'slowdown' in their acceleration as they get closer and closer to light. The observer would notice that they are lorentz-contracted and all that jazz but it's not going to change anything from the frame of reference on the ship, in which they are just as stationary to themselves as the observer is to himself. Even if mass did increase from their point of view, wouldn't that just mean their fuel got heavier, and thus pushes them enough to equal with how they were pushed before?

It would work as a battery for storing energy, yes, but I'm sure their are better ways to store energy.  If you want to store the energy for a whole star as in this example it would probably be more efficient to put the star out and save the hydrogen for later.

Ah, that's a great idea. How could we put a star out? Other then just siphon matter away...

I suppose we could violently put it out by adding enough iron to the core? I know in fission reactions, you can add a medium that will absorb free neutrons and slow the reaction (normally boron... lead, that kind of thing)... could we do something similiar? Maybe if we built a framework around the star, and extended gigantic rods of some material that could stand up to the interior core of the star, until the fusion reaction didn't have enough space to chain react. Then move the whole construct, as a source of energy. Any more tame ways, short of modifying some universal constant?

[Lazarus Long]

(armrha)
The acceleration effects, mass of the fuel and the mass of the ship, would all be acceleratad and not appear to gain any mass. In fact, they shouldn't measure any 'slowdown' in their acceleration as they get closer and closer to light.

That is not quite correct armrha, rest mass is invariant but relative mass does increase according to Special Relativity and so does density as you approach c. These are key concerns for the energy required to sustain the one gee constant acceleration since that acceleration is a function of the same referent as the ship and the Lorentz Contraction of space for them

Special Relativity
On mass
Relativistic Mass
It is often stated that in special relativity the mass of a body increases as its velocity increases, notably in older textbooks and in some introductory physics courses. However, this statement depends on one's definition of mass, and in SR there are actually two different notions of mass. The equations above use what is called the invariant mass or rest mass m. This mass is an invariant quantity, meaning that it is the same for all inertial observers. In particular, the invariant mass does not increase with velocity.

Another definition of mass m is the relativistic mass which is given by

M=ym where y is the Lorentz factor



Since y increases with velocity so does the relativistic mass. This definition is more consistent with (relativistic) length and time and convenient for some purposes. In particular, one can write the equations for energy and momentum as

E=Mc²
p=Mv

which are valid in all reference frames. If the velocity is zero the relativistic mass and the invariant mass become equal.

Neither definition is right or wrong. However, many physicists dislike the concept of relativistic mass because it changes under a Lorentz transformation; they prefer to formulate the special theory of relativity in terms of invariant quantities. The invariant mass is an important quantity in general relativity and quantum field theory. Thus many physicists simply refer to the mass when they actually mean the invariant mass, while they refer to relativistic energy instead of relativistic mass.

Also there is the deceleration side of the energy equation as you would have to basically waste fuel to and begin a powered deceleration halfway to your destination. Spining the ship, accelerating to velocity faster using Hohmann based slingshot trajectories to also scoop fuel from the upper atmosphere of the Gas Giants and then after achieving cruise velocity just coasting until a closer approach and deceleration into the less charted region of space is not only more energy efficient but reduces many risks.

BTW at relativistic velocity there is also a problem with significantly higher shield requirements ad this is the reference that elrond was looking for.

http://en.wikipedia....i/Time_dilation
Time dilation and space flight
Time dilation could make it possible to travel "into the future": if we could accelerate a starship enough, one year aboard the ship might correspond to ten years outside. Indeed, a constant 1g acceleration would permit humans to circumnavigate the known Universe (with a radius of some 15 billion light years) in under a subjective lifetime. A more likely use of this effect would be to enable humans to travel to nearby stars without spending their entire lives aboard the ship. However, any such use of this effect would require an entirely new method of propulsion.

A further problem with relativistic travel is that the interstellar medium would turn into a stream of cosmic rays that would destroy the ship unless stark radiation protection measures were taken.

And lastly with respect to energy don't forget that the faster you are traveling the even faster you have to accelerate the mass of your thrust to sustain an acceleration. Conventional plasmas are really insufficient as you start getting seriously *relativistic* because Newtonian physics fails.

SR & Mass, Momentum and Energy

In addition to modifying notions of space and time, special relativity forces one to reconsider the concepts of mass, momentum, and energy, all of which are important constructs in Newtonian mechanics. Special relativity shows, in fact, that these concepts are all different aspects of the same physical quantity in much the same way that it shows space and time to be interrelated.

There are a couple of (equivalent) ways to define momentum and energy in SR. One method uses conservation laws. If these laws are to remain valid in SR they must be true in every possible reference frame. However, if one does some simple thought experiments using the Newtonian definitions of momentum and energy one sees that these quantities are not conserved in SR. One can rescue the idea of conservation by making some small modifications to the definitions to account for relativistic velocities. It is these new definitions which are taken as the correct ones for momentum and energy in SR.

[Lazarus Long]

BTW they have pretty much killed the Prometheus project and that was the best chance of a building a nuclear rocket we had. Now they seem more interested in blowing things up with nuclear energy than even flying to Mars.


Prometheus, ISS Research Cuts Help Pay for Shuttle and Hubble Repair Bills
http://story.news.ya...bblerepairbills

[eternaltraveler]

Ah, that's a great idea. How could we put a star out? Other then just siphon matter away...

I was more or less assuming that a civilization capable of turning a star into a giant laser would be able to figure out how to put it out too )

siphoning off the matter would probably be best if you don't want it to collapse

[eternaltraveler]

Another definition of mass m is the relativistic mass which is given by

M=ym

Since yincreases with velocity so does the relativistic mass. This definition is more consistent with (relativistic) length and time and convenient for some purposes. In particular, one can write the equations for energy and momentum as

E=Mc²
p=Mv

This is true for all reference frames. However you have to keep in mind that when you are on such a vessel it is the universe you are going to apply these equations too. Not the ship you are standing on. If you are going 99% of c relative to the universe you are still stationary relative to yourself.

And lastly with respect to energy don't forget that the faster you are traveling the even faster you have to accelerate the mass of your thrust to sustain an acceleration. Conventional plasmas are really insufficient as you start getting seriously *relativistic* because Newtonian physics fails.

The thrust is still coming out the back of the vessel at the same velocity relative to the ship. It would still be pushed. If you threw a rock out the back of the ship it would still displace the ship just as much as though you did it stationary from near earth space.

[eternaltraveler]

BTW at relativistic velocity there is also a problem with significantly higher shield requirements ad this is the reference that elrond was looking for.

http://en.wikipedia....i/Time_dilation
Time dilation and space flight
Time dilation could make it possible to travel "into the future": if we could accelerate a starship enough, one year aboard the ship might correspond to ten years outside. Indeed, a constant 1g acceleration would permit humans to circumnavigate the known Universe (with a radius of some 15 billion light years) in under a subjective lifetime. A more likely use of this effect would be to enable humans to travel to nearby stars without spending their entire lives aboard the ship. However, any such use of this effect would require an entirely new method of propulsion.

A further problem with relativistic travel is that the interstellar medium would turn into a stream of cosmic rays that would destroy the ship unless stark radiation protection measures were taken.

This certainly is true. Shielding would be a problem

Edit: The mechanism of the eletromagnetic vortex of the RAM would naturally tend to act as a shield (deflecting charged particles away from living areas and into the reactor, and pretty much everything out there is charged). There would of course be limits to this. I very much doubt that anything resembling organic meat bags like us would be flying around on these anyway. Whether or not the building of this is possible relativly soon, it probably wouldn't happen until a post singularity environment.

Edited by elrond, 19 May 2005 - 10:02 AM.