The Theory Of Relativity

mitchellmckain

Jun 1 2005, 05:27 AM

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?

QUOTE

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

Jun 1 2005, 07:41 AM

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

Jun 1 2005, 10:30 AM

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

Jun 1 2005, 02:06 PM

QUOTE(jet @ Jun 1 2005, 01:11 PM)

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

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... :-)

techocian

Jun 1 2005, 07:37 PM

QUOTE

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

Jun 1 2005, 08:52 PM

QUOTE(jet @ Jun 1 2005, 01:41 AM)

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.

QUOTE

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.

QUOTE

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.

mitchellmckain

Jun 2 2005, 09:05 AM

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 = 1.5
95% of the speed of light is gamma = 3.2
99% of the speed of light is gamma = 7
99.5% of the speed of light is gamma = 10
99.995% of the speed of light is gamma = 100
100% of the speed of light is gamma = infinite

This 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

Jun 2 2005, 11:21 AM

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

Jun 2 2005, 01:02 PM

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

Jun 3 2005, 12:55 AM

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.

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yobster

Dec 14 2006, 05:03 PM

am I right in thinking that time even passes at a different rate when you are on a train, or a plane?

I remember reading that if you throw a ball in the air when you are on a train it will seem to be in the air for longer if you are watching from a stationary point..

would this mean that time passes ever so slightly differently if I was jogging? could someone explain to me how this works? - or is it just one of those things which just happens, without any explaination.. I'm just confusing myself now.

Vicious_AD

Mar 3 2006, 11:00 PM

I've been having a debate with a few friends lately about this sort of thing. I can walk on my hands, so I have deduced that standing on my hands, by the theory of relativity, is in fact me carrying the earth. Since there is no up or down in space, and there is no motion in space because relatively everything is in constant motion, then while the mass of the earth is drawing me towards it's center, it is coming towards me as well (both are moving towards eachother according to Einstein). Holding something is defined basically as stopping something from falling by impeding it with another material object. so since there is no "falling" in space, I am technically holding the earth as it holds me, right? Considering the earth and I as two material bodies rather than the earth being my home and planet, instead thinking of it as two marbles in the same ocean.

Does anyone agree with this? I can't get some of my friends to understand.

mitchellmckain

Mar 3 2006, 10:26 AM

Well I think this thread has proved my point that many people put more faith in science fiction than in science. Many people do not even bother understanding what limitations are implied by the theory of relativity before they are looking for some crazy way to get past the speed of light.

Relativity does not restrict our ability to travel long distances in space. You can go accross the galaxy (100,000 light years) in as short a time as you like provided you can supply the enormous energy required and endure the tremendous acceleration. HOWEVER, if we restrict ourselves to reasonable accelerations and energy then it will take a few years to get anywhere (like the nearest star 4 light years away) just because it takes a couple years just to get near the speed of light at a reasonable acceleration (1 g = 9.8 m/s^2), but once this is done we can cross large distances fairly quickly.

4 light years will take about 4 years on board ship
10 light years will take about 6.5 years on board ship
100 light years will take about 19 years on board ship
1000 light years will take about 62 years on board ship

Since there are over a hundred stars known to be within 20 light years, a 10 year trip can get us to many destinations. And if we can manage higher accelerations we can cut these times down tremendously. For example at four times the acceleration 39.2 m/s^2 we cut these times in half. But anyway the problems here are with engineering not with relativity!

What relativity does mean for interstellar travel is that it is basically a one-way trip, in the sense that you cannot come back in time for dinner, or even for your friend's next birthday. Although you can get where you are going pretty fast, time passes much faster for those you leave behind.

during the 4 light year trip about 6 years will pass on earth
during the 10 light year trip about 12 years will pass on earth
during the 100 light year trip about 102 years will pass on earth
during the 1000 light year trip about 1002 years will pass on earth

Relativity isolates the locations from one another so that what happens at one location cannot effect another location for a long time. This makes things like government and trade very difficult and unlikely over inter-stellar distances. This rules out star trek and star wars but not interstellar travel.

YudzzY

Sep 26 2005, 01:28 PM

relativity is what differentiate us!
like everyone is beautiful, but some are more beautiful and some less, hence its relative as you are talking to your distance topic!
about the limits, well what has a definite limit?! thats is how life is! oh well..

mitchellmckain

Sep 14 2005, 07:43 AM

QUOTE(DigitalDingo @ Sep 13 2005, 12:57 PM)

You're right, I should have thought of that with the aging...

But I still don't agree with you saying "We can get anywhere as fast as we would like." The theory of relativity forbids that - which you fully agree with later...

For the people on the ship they can get anywhere as fast as they would like, it is just for the for the people back on earth watching that it takes so long. So "would be space emperors" must either stay on a planet to rule it while space ships crawl among the stars like snails or go on the space ships themselves where the people on the planets can pretty much ignore him. Of course the scavenger like aliens in the sci fi hit "Independence Day" would certainly be a be a problem (at least if relativity were the only obstical).

QUOTE(DigitalDingo @ Sep 13 2005, 12:57 PM)

Are you sure of this? I could have sworn that many scientists saw the tachyons as a possible solution to many observations, including the accelerating expansion of our universe.

Well the last class I had two years ago when I finished my masters in physics was a pretty up to date class on String Theory. And one of the key historical developments was solving the "tachyon problem" (which meant figuring out how to make sure tachyons don't show up in the theory).

QUOTE(DigitalDingo @ Sep 13 2005, 12:57 PM)

But nevertheless in 1973 Philip Crough and Roger Clay fell over an interesting observation using a large particle detector. They saw what some expects to be a superluminal particle (a particle that travels faster than light).
This result has never been reproduced so we can’t make any conclusions upon that. My intension was only to show, that some people still believe in these particles.

The essence of science is that it can be reproduced. Here in Utah we had that cold fusion fiasco/scandal where some scientists had people convinced they had found evendence for cold fusion, but it turned out to be a scam. Reproducible results is the only thng that seperates science from fraud (or big blunders).

As for believing in tachyons I and all the physicists in the world are completely outnumbered by the star trek fans.

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

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

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