how long would it take to travel a light-year?

Discussion in 'Astronomy, Exobiology, & Cosmology' started by spankyface, Nov 29, 2001.

  1. billvon Valued Senior Member

    Are we talking aliens? The Illuminati? The military-industrial shadow complex? The secret world government?

    Just want to know what sort of conspiracy we're going with here . . . .

    No, none of the nukes we have were made in the 1940's. They didn't even have a working thermonuclear bomb then.
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  3. Fraggle Rocker Staff Member

    I'm sure it's my own feeble memory. I'm not really sure how close they thought the nearest habitable planet is, and that's perhaps the most important variable in the calculation. So blame me, not them. Most "hard" sci-fi writers have at least an intelligent layman's knowledge of physics and astronomy, so they wouldn't bungle something that simple.

    No. Actually, it's you (as usual!) who don't know what you're talking about. The "atomic bombs" of the 1940s got their energy from fission. The next generation of "hydrogen bombs" got theirs from fusion. I'm not going to bother looking it up for your benefit because you just don't give a shit about accuracy and anyone else here who's interested will find it on Wikipedia in about 45 seconds... but I'm pretty sure the difference is at least two orders of magnitude: a factor of 100.

    The early bombs were measured in kilotons of TNT. Today's are measured in megatons. Some of that is sheer size, but a lot of it is the power of the nuclear reaction.

    You really need to learn how to use the internet for collecting information and making yourself smarter, instead of propagating lunacy and making yourself look like an idiot.

    No one expects you to explain the Theory of Relativity to us (which is essential to understanding how nuclear weapons work,) but if you're going to blabber about nuclear weapons you should at least have a layman's familiarity with their history.

    You really do make yourself look like an idiot. I'm not exaggerating and I'm not trying to be unkind. I'm just trying to let you know that no one here has the tiniest bit of respect for you, because absolutely everything you say is utter bullshit. Most people don't like to be perceived that way.
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  5. Write4U Valued Senior Member

    A LY is a fixed distance. The duration of traversing that distance would depend on your speed of travel.
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  7. Fraggle Rocker Staff Member

    To two significant digits, one light-year = 5.9 trillion miles = 9.5 trillion kilometers.

    That's about 70,000 times the distance from the Earth to the Sun. The diameter of the universe is roughly 200 billion light-years.

    When they're actually doing calculations, scientists prefer to use the parsec as a unit of distance. That's about three and a quarter light years.
    Last edited: Jul 8, 2013
  8. enlighteneDone Banned Banned

    If you traveled a Light year at light speed would it take a year for an observer on Earth to notice the person has traveled the distance? or two years?
  9. Fraggle Rocker Staff Member

    First, the observer has to wait a year for you to complete your journey. Then, he has to wait another year for the light from your ship to travel back to earth. He won't be able to see you from so far away, but presumably you'll be transmitting an electronic signal, which travels at the speed of light.

    Duh? I can see why this guy was banned.
  10. Anthony_ Registered Member

    ill quote an example in pioneer 10 probe, the pioneer 10 has been traveling for more than 40 years @ an average speed of 50000 miles per hour, in 40 years and going at that amazing speed it has achieved only 10-11 light/hours, in other words it has travelled i lil bit over 0.001% of a ly, but based in recent projects i think we'll be able to see a light year covered by a man made machine in our lifetime (hope)
  11. Rich2733 Registered Member

    [QUOTyface, post: 64800, member: 4047"]I'm not so keen on the calculations needed, but with current technology, how long would a light-year-long trip take? 1500 years? 200?[/QUOTE]
    Just take 186,000x60x60how fast your going and thats how many years it would take to travel a light year. 186,000x60x60÷18,000=37,200 years
  12. Rich2733 Registered Member

    Just take 186,000x60x60÷ how fast your going, that how many years it will take to go a light year. ex; 186,000x60x60÷18,000=37,200 years
  13. danshawen Valued Senior Member

    Escape velocity from Earth is about 20K mph, and if we can do that, you can go much faster with the same burn from the moon.

    The biggest thing we have to safely slingshot from in the solar system is Jupiter, so that would give your craft another needed boost, but still nowhere near light speed @ 186,272 mps.

    If you could catch up to something like a comet (already at escape velocity for our solar system) on its way out, in a direction you wished to go, or even if you could manipulate an asteroid to fall into the sun to provide you with the needed boost in the right direction, you could go somewhat faster/further.

    Ion power seems to be the way to go. Gram per gram, the continuous thrusts these babies are capable of are nothing short of astounding compared to current rocket boosters. For more info on this, check out ionokraft / ionocraft. And best of all, you'd have a ready means for slowing yourself down a shorter distance before arriving at your destination.
  14. origin In a democracy you deserve the leaders you elect. Valued Senior Member

    Actually Venus is much better than Jupiter to accelerate a ship due to the faster orbital speed of Venus.
  15. sideshowbob Sorry, wrong number. Valued Senior Member

    It's a great place to find out you don't know what you're talking about.

    Please Register or Log in to view the hidden image!

  16. origin In a democracy you deserve the leaders you elect. Valued Senior Member

    Huh? If you could catch up to a comet then you would be going faster than the comet, so what is the point of there being a comet in your scenario?
  17. Write4U Valued Senior Member

    A "lightyear' is a compound term consisting of two separate parts; speed of light (c) and length of time (365 earth days)
    We often do use the term for convenience when addressing cosmological distances.
    A similar term can be found in " 100 miles p/hour" for a car built to travel at 100 m/hr, 1 "carhour".
    How far does a car traveling for 1 hour at 100 miles p/hr? It depends on the windings of the road, doesn't it? If it is a winding road the car may travel 100 miles but only cover 50 miles as the "crow flies".

    Thus a light year is a measurement of distance traveled by light in the course of 1 earth year, IN A VACUUM!. But it depends on the medium how much distance is in fact covered in a lightyear. It may take a photon 100 (light) years to escape the density of our sun, but then it travels 8 lightminutes to reach earth. Note: that the photon traveled the entire time @ "c".

    Thus to equate a lightyear with a specific distance is not correct or at least not complete.

    As is often the case, the OP is a condensed question which cannot be answered with a single explanation.
    Last edited: Jan 7, 2015
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  18. AlexG Like nailing Jello to a tree Valued Senior Member

    A light year is a unit of distance equal to 9.4605284 × 1012 kilometers.
  19. Write4U Valued Senior Member

    Wow, you are telling me that a lightyear is roughly 9.5 x 1012 km = 9614 km in distance?

    And that " distance is based on what speed and length of time?
    Last edited: Jan 8, 2015
  20. Janus58 Valued Senior Member

    No he meant 9.5 x 10^12 km (9,460,730,472,500.8 km to be exact).

    It is the distance light travels in a vacuum in one Julian year. (365.25 days)
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  21. AlexG Like nailing Jello to a tree Valued Senior Member

    Forgot the superscript.
  22. Write4U Valued Senior Member

    From post # 34
    Seems to me we are in total agreement.
  23. paddoboy Valued Senior Member

    Won't argue with your maths, but that is of course from our perspective.
    From a photon of light's perspective, it could traverse the Universe in an instant of time...infinite time dilation no less.
    Just saw that as an interesting addition.

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