The Theory Of Relativity What does it mean for space travel?

[mitchellmckain 0]

I have been having a lot of fun in the Religion and philosophy forum talking about the implications of quantum physics and chaos theory for human consciousness. When I brought up another topic which I thought would be more appropriate for this forum. So I am going to quote myself from that other forum to start a discussion. I do wonder how many people talking here understand relativity and how many reject it?

So many people cannot except the failure of thier dreams of the human race traveling the the stars like in Star Trek that they refuse to accept the basic facts of relativity.  They even refuse to understand those basic facts to see what relativity is actually saying about what is possible and what is not.  For example, the nearest star is about 4 light years away, so assuming we can surpass any current technological limitations how fast do think it would take a traveler to get there?  How about the Ring Nebula 2300 light years away? What are the limits of relativity and what are the technological limitations? What does relativity really say about traveling to these places?

[jet 0]

I understand all the physics and laws behind most discussions, because my dad was a physicist (and refuses to shut up at any time during the day or night when we're with him)

 

Having read my way through most of the school library's science fiction stands (and comics, lol), the most common theory about how to get around those distances is hyperspace, or something like that. The ability to enter another dimensional reality and hurtle through vacuums at speeds otherwise impossible. This idea may be possible, but looking at science so far nobody's actually come up with any theories on how to get into hyperspace. Nobody at the moment knows what's going on behind that little (or big) red button people press to enter hyperspace. In some books hyperspace can only be entered at certain places, but the facts behind that are scanty. Yes, some places have a stronger concentration of gases, a lack of oxygen etc, but the switch between two kinds of planes shouldn't be affected by those little details.

 

The Hitchiker's Guide to the Galaxy has a funny thing called the improbability factor drive. After reading through the sections about the Heart of Gold analytically (which you're obviously not meant to do because the book is so tedious and boring that way), I found it makes absolutely no sense whatsoever. It should probably be noted here that Douglas Adams was slightly drunk when he thought of the idea behind the book.

 

Some people believe that because of certain factors to do with light, time and speed (and no, I didn't understand), if you move at the speed of light time stops or something like taht. If you move faster than the speed of light, time goes backwards (so that's how Superman managed to reverse time by flying around the planet, lol. Had nothing to do with turning gravity at all). I don't think that's true though. If you move faster than the speed of light, and your racing a beam of light, you eventually outstrip it and fly alone in darkness with the light behind. Isn't that just more logical?

 

I don't mind not being able to fly to one side of the galaxy to another in just a few days. I don't mind being stuck here on Earth for the rest of my life. What's there to see out there anyway?

[qwijibow 0]

is faster than light travel possable ? no idea, but if it is possable, its certainly not with current propulsion techniques (warp drive anyone ? lol)however i was reading a magazine called new scientist about quantum entanglement.basically, faster than light communication. i dont know if anyone has managed to use it yet, but i remember it was proved possable.teleportation ?

[kaputnik 0]

It should probably be noted here that Douglas Adams was slightly drunk when he thought of the idea behind the book.

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LOL's ... and I'd seriously thought he'd smoked a fist sized joint when he wrote most of the book.. in reality though.. a great many ideas of Adams' make a bit of sense.. more specifically, where travel in space is concerned.. the only limitation is the human brain and it's capacity to fully comprehend or 'manufacture' a thought ..

 

By manufacture thought I mean original ideas.. there's no such thing.. the brain is fed information and produces a mish-mash of gibberish - which it then sorts though to grab onto anything that closely resembles sense.. I'm not saying that we as humans are limited because of the processing power of our brains.. what i'm saying is that the prosessing power of a single brain is only as good as the information that it has recieved and the information that it is capable of processing (the sensable bit) after it is through with all the rubbish.. what happens (and this is something I've jsut conjured up) .. is that the brain tries innumerable combinations of thoughts, shuffling between facts, ideas.. and does so on a continous basis.. it then tries to create new combinations of processed thoughts, to come up with original though..

 

TRIZ is a system of recording ideas and thoughts and even processess right through the span of all verticals to be able to come up with ideas never thought about .. sooner or later. the concept of utilizing TRIZ for the human mind may just become possibel... all it'll take is some sort of a miniture implant in the brain that communicates with a central node someplace and records the generic and possibly the more specific ideas of an individual.. so when another person has a problem to solve.. say.. how to get to Alpha Centurai.. inside of 20 minutes... the nodal computer kicks to life... searches through related material that may provide a solution.. searching through verticals.. between industries... amongst absolutely urelated fields.. to possibly come up with a group of human brains who have thought about the problem and have come up with viable solutions or part solutions to problems within the larger problem... AND I even have a sneaking feeling that this is what Google is out to do.. It's not going to happen with conventional computing.. but quantum computers are at the stage of development paralell to what our modern day computers were 40 years ago.. so we just may see things like this in the very near future..

 

As soon as we've solved the problem of getting the right type of information and ideas to the people thinking about specific problems like inter planetary space travel.. and minds capable of thinking at the same platform are connected at the rather slow speed of thought.. then, we'll get there.. we definately will.. and I'd like to see it happen during my lifetime... :-)

[evion 0]

So many people cannot except the failure of thier dreams of the human race traveling the the stars like in Star Trek that they refuse to accept the basic facts of relativity.

Based on this, does anybody realise that many people are also having the same problem with Star Wars. Firstly, it is very imaginative and this concludes the "Hey i wanna have a light saber" part of the story.
Secondly, people are going madly crazy over it because of the "cool moves" and all the "cool" gadgets that the movie bestows upon the audience. I've even heard of a religion called the "Jedi" - yes, here on Earth - they believe in "the Force" (A special thing in Star Wars that enables Jedi's (In the movie not real life!) to telepathically move matter).
Everyone is going Star Wars crazy and no one is here to give a stand and say something like: "Star Wars is a movie - an imagined fantasy that most probably cannot be real in our life. So ditch the imagnination and go on with your life!"

Now isnt that something you would like to hear?

[mitchellmckain 0]

I understand all the physics and laws behind most discussions, because my dad was a physicist (and refuses to shut up at any time during the day or night when we're with him)

That familiy situation sounds so familiar, so like I totally sympathize......

.............................................

...........with your dad.

 

But like so many people you quickly start looking for a way around relativity somehow. So this makes it appear that the sci fi had more impact than your dad. You did not answer the questions and no one else has either. So until someone does I still have (the possibly false or hopefully false) impression that no one here understands it.

 

Look I love science fiction just as much as I love fantasy. Its just that I don't see much difference between them. It all fun but its all fantasy. I even take it quite seriously. I think stories are very important. Whether the stories are fantasy, or history or the bible, it doesn't make much difference to me.

 

Some people believe that because of certain factors to do with light, time and speed (and no, I didn't understand), if you move at the speed of light time stops or something like taht. If you move faster than the speed of light, time goes backwards (so that's how Superman managed to reverse time by flying around the planet, lol. Had nothing to do with turning gravity at all). I don't think that's true though. If you move faster than the speed of light, and your racing a beam of light, you eventually outstrip it and fly alone in darkness with the light behind. Isn't that just more logical?

Faster than light travel involves many logical contradictions in physics.

Even traveling at the speed of light is impossible for any object with mass; it would take an infinite amout of energy. Faster than light travel would not cause time to flow backward. The problem is that the relativity of simultaneity makes faster than light travel logically equivalent to time travel. One of the main effects of accelerating to an appreciable fraction of the speed of light is that the percieved order of events, separated by large distances in the direction of your motion, changes. This does not violate causality because the spatial separation between these events must be great enough so than nothing can get from one event to the other without exceeding the speed of light. So if there was anything that could travel faster the speed, the order of events involving those things would be ambiguous and for someone passing by at high velocity those things could arrive before they leave. Two people traveling faster than the speed of light could create the same kind of paradox you have with time travel. For example, if you see an ftl traveler kill your friend, you use ftl to go kill that traveler before he left the place he came from and thus before he killed your friend.

 

I don't mind not being able to fly to one side of the galaxy to another in just a few days. I don't mind being stuck here on Earth for the rest of my life. What's there to see out there anyway?

Well you might as well feel that way since we cannot do it anyway and there is not much point in wishful thinking.  And yet what do you say to someone who doesn't see the point in skiing who has never tried it, or someone who says that about going to another country, or about going to the national parks of Utah.

 

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[mitchellmckain 0]

Oops looks like the last quote in the last post was missing a quote termination and my reply was inside the quote.You cannot catch up to something going the speed of light because no matter how fast you go it still races ahead of you at the same speed. This not true of sound for example. If you travel near the speed of sound and make make a noise, the sound from that noise move ahead of you very slowly. This is what creates a sonic boom. The sound of a jet traveling close to the speed of sound barely moves ahead of the jet as the jet moves so the sound just keeps building up in front of the jet so when the jet passes all of the sound hits you at the same time.But something like 95% of the speed of light is deceptive because when you are moving that fast and you shine a light, that light moves out ahead of you as were not moving at all. You could say that we have a much more meaningful measure of the speed when you are moving close to the speed of light called gamma.75% of the speed of light is gamma = 1.595% of the speed of light is gamma = 3.299% of the speed of light is gamma = 799.5% of the speed of light is gamma = 1099.995% of the speed of light is gamma = 100100% of the speed of light is gamma = infiniteThis gamma tells you a great deal about the effects of relativity but for now lets just consider two things. The first is that the energy required to get to the higher velocities is basically proportional to gamma, so it takes 10 times as much energy to get to 99.995% of the speed of light as it does to get to only 99.5% of the speed of light. The second is that gamma is much more like a speed because it adds up. Here is what I mean. If you travel 75% of the speed of light then you shoot something away from you in the same direction so that it moves away from you at what looks like 75% of the speed of light then how fast is it going. Well it is not going 75%+75% = 150%, not at all. But you can get the correct answer adding gamma 1.5+1.5 = gamma 3.0, which is 94.3% of the speed of light.The point here is that the speed of light is really like an inifinite speed, because no matter how much faster you go you never really get any closer to the real speed of light.

[jet 0]

Is like an infinite speed, but is not exactly an infinite speed. According to the lovely google calculator which I have instead of the smiling attractive hostess, the speed of light = 299 792 458 m / s. The point of hyperspace, travelling through a vacuum, is lack of friction. With just a little bit of gas and mostly nothingness out in space, the friction is still there. So it drags your spaceship/whatever down. In fact, the speed at which most things move at is determined by the surface area because the more surface area, the more friction. There's also something about streamlining, which is sort of the same principle. Streamlining means more surface area is "latent", so to speak, so there is less surface area exposed to the friction. That's why jumbo jets, though larger than elephants, tend to move a bit faster. If there was nothing at all, in a vacuum, what's there to stop you from moving faster than the speed of light?

[OneStopReefShop 0]

Something you haven't touched on here... is that the "Theory of Relativity" is just that... a Theory! A Very brilliant man postulated that many years past... as to date most of his postulations still stand. However, as man develops technology and evolves... who is to say what was once proven facts will still remain?If you remember back from your History Classes in school... the world was once proven as being "FLAT". Man developed technology... and that more advanced technology helped man to evolve... and with that came added knowledge that no... our world wasn't flat... but a sphere.I guess what my ramblings are trying to say is... we can't even begin to fully understand, or even guess at what the future holds for the Human Race. Many wonderful changes are in store, as well as some not so wonderful, I'm sure. I do very much believe that one day... one year... one century... man (or his descendents) will find a way to explore whats out there... and will make it happen. Man seems to have this problem... "When I want sumptin, I'll figure out how to get it"! *Smile*

[qwijibow 0]

jet, what you dont seem to understand, is that mass and energy are the same thing.the fasdter you go, the more energy you have, and therefore the more mass you have.the more mass you have, the more energy is required to accelerate you.mass increaces exponentially.at the speed of light, you have infinite mass.and an infinite amount of energy is required to accelereate an ininite mass.its got nothing to do with friction.

[mitchellmckain 0]

Even the background microwave radiation which is believed to be a remnant of the big bang in which the universe began is a serious problem but this is a technological consideration.Another big problem is acceleration, if we have to limit ourselves to one gee ( that is 9.8 meters per second squared) then this will really limit how fast we can get to another star. Really high gees would crush us to instant death and perhaps destroy the space ship as well.Another problem is the energy requirements. Getting even close to the speed of light requires an amount of energy equal the mass energy of the whole ship according to E = m c^2. In other word, you would have to use at least half the mass your ship converted to pure energy to get near the speed of light. In fact when you include the need for thrust mass half the orignial mass of your original mass will be needed to get to just 41% of the speed of light.But in my original question I said to assume that all of these problems are taken care of so that they don't introduce any extra limitation on how fast we can get to our destinations. Assume that our only problems is relativity which includes the fact that nothing can go faster than the speed of light.Given these assumptions how fast can we get to the nearest star or the ring nebula?

[szupie 0]

I do understand and grasp the concept of relativity. But, I think that to travel a far distance, such as one of your example, the nearest star, we should not look for an answer that has to do with the Theory of Relativity. I think that wormholes are the key to this.

 

Recently, there are 2 scientists who said that the "semi-classical" wormholes combined with exotic matter would not be stable. I don't know what "semi-classical" means, but they said that it's the ones that are predictable. I don't think the creations of wormholes can be predictable, at least for another 5000 years after they can use wormholes. Wormholes are created "randomly" (To us) by quantum physics, and there isn't any theory yet for the manual creation of wormholes. If we can keep a wormhole that is close to the star open with exotic matter, we can send a spaceship through the hole, then use some device that could move the wormhole towards the star, the first trip would take significantly less time. Then, the following trips would be much easier since the hole is near the star. But, I have no idea how we can move a hole.

 

 

So, the solution would be off the topic description, but might be the best and fastest solution to the problem.

[mitchellmckain 0]

I do understand and grasp the concept of relativity. But, I think that to travel a far distance, such as one of your example, the nearest star, we should not look for an answer that has to do with the Theory of Relativity. I think that wormholes are the key to this.

No you are not off topic, however, you are illustrating perfectly the problem I have been talking about. Everyone puts more faith in science fiction and fantasy than in science, because worm holes are a fantasy. If we did not have solid evidence that they really do exist black holes would be a fantasy too. Do you know that there are catalogues of blackholes and neutron stars, just as there are catalogues of stars and galaxies? The fact that incomplete theories like general relativity can describe wormholes does not mean they exist.

Something you need to understand about general relativity and quantum field theory is that they are theoretical frameworks which like a language can be used to describe just about anything. For example general relativity has been used to describe black holes and the big bang. These could be called theories, but they also have some evidence to back them up. Wormholes have no such evidence and there is not even the smallest reason to think that they really exit.

So before we look to fantasy, how about a little reality. Are you sure there really is a need for these wormholes anyway? First answer the question. If relativity were your only limitation how long would it take you to get to the nearest star (4 light years away) or to the ring nebula (2300 light years away)? What is the effect of relativity on trips to these places?

[iGuest 3]

1. A lot of people are scared that the beliefs they have been subdue to is all wrong. They do not want to take a risk and explore their imagination, in fear that a self-made object will torture them or banish then from "heaven".

2. Light propulsion is only possible if we truly want it to be. There may be a million and one ways of travelling at high-velocity speeds in space, but until we can get along on our planet, dreams of such potential to do better are quashed.

3. People who refuse to accept the basic and most fundamental laws of relativety are doing the right thing in their minds. I do not agree with it, but I do accept that they have a choice. Many scientists have tried to dismiss the laws, and now that they are re-calculating and reviewing them, they have found him to be right.

4. Are warp engines possible? In my eyes, yes. Why not? LINK Shows how the mechanics of it work on Star Trek. And we know already that a lot of Gene Rodenberry's ideas are coming into light. Just the other week I was reading an article in the Focus magazine, about cloaking. A small team of science students somewhere in America have developed a "shield" that engulfs an object, rendering it almost invisibe. I think it used mutli-directional light refraction to make it fit in (don't hold me to that). It is however very unstable and is not perfect at the moment.

5. Wormholes do exist, but they may just be another form of space travel. All theories are working in the beholder. Making it possible is the hard part. Wormholes are not exactly the best thing. They open a gateway between two places. What happens if you want to go somewhere different?
In Babylon 5 I believe they used "hyperspace" or "jump". This mimicked a wormhole, however it appeared that a static station was required to generate it.

6. Sub-spatial sinking. It's what I like to think to be another from of space travel. Sub-spacial sinking isn't actually an "out-there" theory, it is something I cooked up months ago. It envolves any object (in-animate or animate) passing through sub-space folds to reach a new destination. Due to the unkown about entering sub-space this would be another harder from of travel.

7. Movement of light. I undertsand the ferace-wheel notation (go too fast and the people on the outside potentially age faster than those on the wheel). However, I don't think it really applies. When travelling at the speed of sound, people do not age quicker on the outside, it has been proven with anatomical decay of particles at start and finish. Light is just another form of energy. So why, therefore, should people in the object going at light or faster than light speed age slower?

8. Logic. Is something as humans we rely on too much. That and problem solving. Isn't it amazing how we only use upto a quarter of our brain power? This is because logic and problem solving spheres in the brain by-pass many other brain functions. One man's logic is another man's chaos. Logic is denoted by the one who sees the reasoning to the logic, where problem solving has come to a valuable end. Imagine, if we could control our logic and poblem solving to be less sharp. This would raise all of our other functions. There are people out there with elevated expertise. Often it is due to a syndrome or disease or problem. Sernat's syndrome. A person with this syndrome has almost "enlightened" abilities in one sphere of the brain, where the rest is "average" potential. The difference between Sernat's and Autism. Is that autistic's elevated ability in one field, reduces the rest of the brain's stimulation. More power is put into that area than fundamental building blocks. Autistics and Sernat's are like evolution and hyper-evolution. Autistics are challenged when it comes to communication and awareness. Whereas Sernat's are like you and me, but are genious' in a certain field, even at young ages.

[mitchellmckain 0]

Well maybe its time I answer my own question then.The answer is that relativity does not limit how fast you can get to any destination.If all technological issues are dealt with you can get to the closest star or the ring nebula or anywhere else as quickly as you would like.Yes nothing can go faster than the speed of light, but this is a limitation on relative velocity only. It mean that you never see anything go faster than the speed of light. But otherwise the speed of light is like an infinite velocity, and the gamma is a more meaningful measure of the velocity than this relative velocity.Recall from my previous post that 99.5% of the speed of light is gamma = 10Which basically means you have an effective velocity of 10 times the speed of lightso you can get to the nearest star (4 light years away) in 4 tenths of a year or about 5 months.However for the people on earth waching you never exceed the speed of light so as they watch your ship making the trip it takes at least 4 years. So after a round trip you are less than a year older but the people on earth are 8 years older.So the real impact of relativity on space travel is to make it mainly a one way trip. You cannot go out there for recreation or work and expect to come back to a family or people waiting for you. It also makes interstellar government largely unworkable. So the wars for and between interstellar empires in star strek and star wars are fantasy. For long trips you cannot really expect to come back to any recognizable home. But for the adventurous life of a pioneer and colonist, relativity imposes no limitations.No lets deal with some of the other problems. The biggest in my mind is acceleration. The only really safe acceleration is 9.8 m/s^2 or one gee. And at that rate it take a couple years to get near the speed of light. The result is that even the nearest star will take at least 3 years but farther distances like the ring nebula (2300 light years away) would take only about 50 years.The energy requirement is a big requirement and that is assume perfect efficiency in mass to energy conversion. But all this means that the largest portion (more than 75%, for small distances) of the mass of your ship must be fuel for the journey.