Forum Topic
CanadaPhil
MemberOvomorphApr-10-2012 2:31 PMI thought I would post a topic for the start of a discussion on THE SPEED OF LIGHT & THE LIGHT YEAR in relation to Space Travel. I am certainly not a rocket scientist by any means, but there is a lot of confusion in the forums on this subject.
The main problem most people have is that they confusion the these as being one in the same thing, but they are NOT. One is a measure of VELOCITY while the other is a measure of DISTANCE! (Just forget about TIME for right now!)
The [b]SPEED OF LIGHT[/b] is just what is sounds like. It is a measure of VELOCITY. The speed of light in vacuum, usually denoted by c, is a universal physical constant which is important in many areas of practical & theoretical physics currently understood by us. Its value is 299,792,458 metres per second, a figure that is exact since the length of the metre is defined from this constant and the international standard for time.[1] In imperial units this speed is approximately 186,282 miles per second. In metric units this speed is approximately [b] 300,000 kilometers per second.[/b]
According to special relativity, c is the [b]maximum speed at which ALL energy, matter, and information in the universe can travel[/b]. It is the speed that all massless particles and associated fields (including electromagnetic radiation such as light) travel in vacuum. In the Theory of Relativity, c interrelates space and time, and also appears in the famous equation of mass–energy equivalence E = mc2.[2]
Now in contrast, a[b]LIGHT YEAR[/b] is a measure of [b]VAST DISTANCE[/b] not Time as many confuse it with!!! A light-year (ly) is a unit of length, equal to just under [b]10 trillion kilometres[/b] (10×1015 meters, or about [b]6 trillion miles[/b]). As defined by the International Astronomical Union (IAU), a light-year is the distance that light travels in a vacuum in one Julian year.
The light-year is often used to measure distances to stars and other huge distances on a galactic scale, especially in non-specialist and popular science publications, or made up fictional movies!!!!
With respect to this story, the system of interest is the Zeta-Reticulli which is approximately 39 light-years from Earth. In other words, its about [b]39 TRILLION KILOMETERS[/b] from here!!
OK, thats the "coles notes" version. Feel free to add whatever infomation you like....
48 Replies
draekus
MemberOvomorphApr-10-2012 2:41 PMWhat is this "Speed of Light" you speak of!?!?!? Blasphemy, I say to you heretic!!!!
LOL, OK but seriously thanks for the post. Very educational.
CanadaPhil
MemberOvomorphApr-10-2012 2:41 PMExactly...
This is why sci-fi from the beginning has been all about non-sensical bullshit Star Trek plots that absolutely make no sense scientifically.
mw3
MemberOvomorphApr-10-2012 2:42 PMhow much faster than light are thay going givein that lv223 is 39lights a way from are planet?.....
NoXWord
MemberOvomorphApr-10-2012 2:43 PMNice one, Phil
Ridley Scott will eventually tell us how the Queen was born.
Right now we have the Deacon; coming soon the Mercury, the May and the Taylor.
Pulserifle
MemberOvomorphApr-10-2012 2:45 PMAlso, a light year is basicially the distance light travels in a vacuum space over 1 year (365days) and this is then measured in distance.
whiskuz
MemberOvomorphApr-10-2012 2:46 PM@Canada Phil
I disagree. Hard science fiction is very different than science fiction in general with respect the how realistic the plots are.
Pulserifle
MemberOvomorphApr-10-2012 2:50 PMIdd mw3, if they 39 light years away and considering the major difficulties in travelling faster than light then it would be save to say they going be bending time if they only took 5 years to get there.
Zedwardson
MemberOvomorphApr-10-2012 2:51 PMIf for example, a planet is 39 light years away, and it takes 2.5 years to get there.
the ship is traveling ~15.6 times the speed of light. Assuming I did the math right in my head.
mw3
MemberOvomorphApr-10-2012 2:53 PMi thort it was over 2 years to get there?.....i think thay would have to bend space and time..
CanadaPhil
MemberOvomorphApr-10-2012 2:55 PMThe easy way to sum this up is for the purpose of this movie is ...
Zeta-Reticulli is 390 TRILLION KILOMETERS from EARTH.....Thats 390,000,000,000,000 Kilometers!! folks.
And the fastest speed we could achieve realistically (but even that will probably NEVER happen!) is 300,000 kilometers per second (the speed of light!)
mw3
MemberOvomorphApr-10-2012 2:56 PMwounder if thay will say how in the film how thay go faster than light?......
Jason8
MemberOvomorphApr-10-2012 2:57 PMI just have one nit to pick. The Speed of light is revealed by Maxwell's equations for electromagnetic energy. The maximum speed of light has to do with the permitivity of free space. A radio antenna is said to provide an impendence match with free space. Einstein's Special relativity was one of 5 papers he published in 1905 and only dealt with the laws of mechanical motion in a uniformly moving reference frame. It was another 20 years or so before he was able to include light in his General theory to include all of physics. The General theory turned out to be a theory of gravity and deals with the curving of space time and the dilation of time and space at relativistic speeds.
Pulserifle
MemberOvomorphApr-10-2012 3:00 PMConsidering the sheer amount of energy it would take to make a spaceship to travel at light speed ship they have to be using wormholes or bending time although this again you need to be travelling at light speed. All i can say is thank god its just a movie
CanadaPhil
MemberOvomorphApr-10-2012 3:05 PMAnd the other issue which has always been COMPLETELY IGNORED in sci-fi is the effects of Time Dilation!!
I wish I could find it right now, but some time ago I had found this cool site where they were tackling questions of travelling vast distances. For the life of me now I cant find it via Googling. I wish I had bookmarked it. Anyway, I sort of remember the example and the distance in question was very close to our story (34 or 36 light years). In that example, they had surmized that if we could somehow accelerate to something just shy of the full speed of light, it would take approximatey 7 FULL YEARS rocket time to travel that distance. (That is factoring in CONSTANT acceleration at 1g for half of the journey with the balance being required for deceleration).
But remember, that was just the one-way ROCKET TRAVEL TIME... Back on Earth, normal time will STILL have elapsed... in other words 35ish years !!!!!
There is no way around it folks.. unless you introduce completely bs concepts of "magical" super-duper-hyper-velocity Time Travel, humans would NEVER be able to traverse these kinds of distances.
whiskuz
MemberOvomorphApr-10-2012 3:07 PM@Pulserifle
Are you implying bending space is easy?????
I know what you mean though.
Ender
MemberOvomorphApr-10-2012 3:09 PMJust to note the speed of light is not a "velocity". It is simply a speed, which is 299,792,458 meters per second. 2 pieces of data
Velocity is speed in a given direction. 3 pieces of data
Also forget about miles, modern scientists use the metric system
ChrisNilson
MemberOvomorphApr-10-2012 3:09 PMwhere did you go to school?
39Ly at 6 trillion miles/Ly is 234 trillion miles.
Pulserifle
MemberOvomorphApr-10-2012 3:10 PMI would love to be able to work it out and the effects of Time Dilation just to seen if the 39 light years would take the rumoured 2 or 5 year. That way we can rule out wormholes etc.
btw Time Dilation is basically the faster you move the slower the clock goes.
snapper
MemberOvomorphApr-10-2012 3:16 PM" Also forget about miles, modern scientists use the metric system"
Thats ok I am not modern or a scientist !
Zedwardson
MemberOvomorphApr-10-2012 3:17 PMMost science fiction on TV or film does do some sort of hand waving for fast then light travel. Same thing for making artificial gravity and so on. most of the time it is best if this is just hand waved and accepted so that it does not get in the way to the main point, which is to tell a good story.
Though you do have fun ones like Babylon five, which had fast then light travel, but (humans at least) had to deal with Zero gravity or have rotation. Plenty of Science Fiction literature deals with time dialysis, but movies normally shy away from this, for the simple fact of not wanting to spend time explaining the concept.
CanadaPhil
MemberOvomorphApr-10-2012 3:18 PM@Pulse..
Yes... and to add to the Faster you move, this effect is then greatly increased the further and FURTHER you get from Earth.
DJAB
MemberOvomorphApr-10-2012 3:19 PMSo it should take them 3.8 year to get there if they were travelling at the speed of light, but I'm pretty sure they're not they are going faster as detailed in a previous thread I started called "first 12 minutes breakdown" .
Only recently scientist at CERN believed they had found a particle that was travelling faster than light which if harnessed could make time travel a possibility, unfortunately after further investigation it was found to be down to faulty tech. (at least that's what we've been told)
Maybe in 2089 we will have discovered that particle and harnessed its qualities.
anyway this is a Sci-Fi movie it doesn't need to be accurate in any way shape or form if that were the case id be more concerned about the aliens than the speed the ship is going.
NoXWord
MemberOvomorphApr-10-2012 3:20 PMLol, then a light year is around 47000000000000 furlongs +/- 15 inches
Ridley Scott will eventually tell us how the Queen was born.
Right now we have the Deacon; coming soon the Mercury, the May and the Taylor.
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