JoelP
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| posted on 21/5/06 at 10:55 AM |
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i think we're both singing from the same sheet here si, we agree the dot isnt real or continous and that it (the dot, not the light) can appear
to move damned fast 
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DIY Si
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| posted on 21/5/06 at 11:03 AM |
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I think we're arguing over a very minor point in all fairness. I hear what you're saying, just partly being awkward and partly just being
me.  Just wasn't sure if you quite understood the thing about it being a different dot.
And about the water cannon, it'll take 3 secs for the water to move round not 1, since you forgot the 2 secs for it to get to the wall. 
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MikeR
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| posted on 21/5/06 at 12:53 PM |
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exactly, the nozel will move round in 1 second but it will take the point of water hitting hte wall 3 seconds.
hold on ....... have i just argued against my own point here?
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JoelP
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| posted on 21/5/06 at 02:49 PM |
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sorry, both wrong! the original line of water will continue hitting the wall for two seconds before it starts to move! hence still only a
second. Think if you rotated it continously, it would have to keep up.
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Liam
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| posted on 21/5/06 at 03:37 PM |
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Yeah there's definately no problem with the 'dot' moving faster than the speed of light, and it definately can. As has been
explained its intuitive to consider the dot as one single entity moving, but it isn't at all. You're just spraying a load of separate
photons out into the universe at a big wall, all at the speed of light, and seeing [some of] them reflect back in a big mexican wave of photons. No
single thing is making the faster-than-light-speed journey along the wall that the dot seems to make. Seeing that dot appear to move faster than
light is no more amazing than the fact that you can simultaneously observe stars that are millions of light years apart by just looking into the
sky.
Liam
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DIY Si
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| posted on 21/5/06 at 07:01 PM |
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Nope, still 3 sec 1 sec to move, 2 more for the water to hhit the wall at the new point.
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JoelP
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| posted on 21/5/06 at 07:18 PM |
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im going to argue for the sake of it now 
You're firing water at a wall and its taking two second to reach the wall. You spin it round, taking 1 second to travel the 180 degrees. At this
point, water is still hitting the original spot and will do for another second, and at the end of this second second , water will be halfway towards
the new spot. From now, its only one second til water hits the new spot, and if you wanted to be picky, you can imagine the splodge rushing all the
way round the wall, following the path of the nozzle but 2 seconds delayed, since its taken 2 seconds to reach every spot the nozzle aimed at.
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DIY Si
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| posted on 21/5/06 at 07:27 PM |
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We're still arqueing about the dot type thing really. Just the same as with the light. New point, new splodge.....
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Liam
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| posted on 21/5/06 at 07:50 PM |
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Er you're both correct but giving times for different events aren't you?...
DIY Si is saying the total time from the start of the movement of the nozzle to the splodge/dot arriving in the new position on the wall is 3 seconds.
That's correct.
JoelP is saying the time the splodge/dot takes to move on the wall is just 1 second, matching the movement of the nozzle. Also correct. The
splodge/dot simply follows the hose 2 seconds later. For the first 2 of DIY Si's 3 seconds the splodge/dot doesn't go anywhere, then it
moves accross the wall in 1 second, 'magically' exceeding the speed-of-water, just as the laser dot appears to exceed the
speed-of-light.
Liam
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DIY Si
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| posted on 21/5/06 at 07:54 PM |
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what he said really ^. We're both right. Which is nice, but on different things.
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JoelP
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| posted on 21/5/06 at 08:38 PM |
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d'oh
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DIY Si
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| posted on 21/5/06 at 08:40 PM |
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Indeed. And it only took 3-4 pages for someone else to point it out.
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Liam
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| posted on 21/5/06 at 10:15 PM |
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Heh heh
Incidentally, the best laymans guide to getting your head round the counter-intuitive wierdness of special relativity I've ever found is
here...
HERE
Manages to show all the concepts very clearly with good diagrams and almost no maths at all!
Hmmmm now then, time to move onto general relativity.... I'll get me coat...
Liam
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trogdor
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| posted on 22/5/06 at 05:27 PM |
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to make things even weirder, scientists have recently manged to teleport a laser across a room. which is pretty impressive!
also there is a pretty good thery going round that it may be possible to send photons back in time. which means info can be sent back in time.
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jollygreengiant
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| posted on 22/5/06 at 06:16 PM |
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I sent this post in on christmas day 2007
Beware of the Goldfish in the tulip mines. The ONLY defence against them is smoking peanut butter sandwiches.
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Simon
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| posted on 22/5/06 at 09:22 PM |
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quote:
Originally posted by trogdor
to make things even weirder, scientists have recently manged to teleport a laser across a room. which is pretty impressive!
also there is a pretty good thery going round that it may be possible to send photons back in time. which means info can be sent back in time.
Well, I guess they haven't succeeded as I see no mention of warp engines or working teleporters (no, a laser doesn't count - I want
matter!)
For what it's worth, I don't believe that the "speed of light" is as fast as you can go. There may be a limit to physical
movement, but I reckon that once the theory of warping spacetime, then real distances will be covered (yeah, as will be invented by Zephraim Cochrain
- hey maybe they have been transmitting data back through time).
ATB
Simon
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JoelP
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| posted on 22/5/06 at 09:30 PM |
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warp speed mr sulu!
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DIY Si
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| posted on 22/5/06 at 09:30 PM |
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It could become possible if someone figures out how to warp space time enough to create 'tunnels' in spacetime. Can't see it
happening anytime soon, as this would surely require an absolutely awesome amount of power? Ie more than a couple (?) of large stars create. But then
in the past it was considered impossable to go over 35 mph in a train as they thought the speed would suck the air out of your lungs and kill you, so
who knows what tomorrow brings? A apart from more bloody rain and another exciting day at work.
[Edited on 22/5/06 by DIY Si]
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trogdor
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| posted on 23/5/06 at 01:37 PM |
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yeah its wierd to think when that guy builds this light time machine of his, if it works then messages will come from the future straight away. would
be interesting to see what is sent back!
yeah there is the whole idea of wormholes allowing "shortcuts" through space. it depends on the idea of space being curved tho.
if we are gonna talk about wormholes then we may as well mention parallel universes. they are really interesting! from the work done on string and M
theory which is based on parallel univeres there is apparently 11 diamentions, 10 space one time. instead of 3 space and one time! also from this work
they beleive gravity doesn't originate from this universe. It "leaks" in from a parallel universe, this would explain why its so
weak!
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02GF74
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| posted on 25/5/06 at 11:22 AM |
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quote:
Originally posted by trogdor
yeah its wierd to think when that guy builds this light time machine of his, if it works then messages will come from the future straight away. would
be interesting to see what is sent back!
yeah there is the whole idea of wormholes allowing "shortcuts" through space. it depends on the idea of space being curved tho.
if we are gonna talk about wormholes then we may as well mention parallel universes. they are really interesting! from the work done on string and M
theory which is based on parallel univeres there is apparently 11 diamentions, 10 space one time. instead of 3 space and one time! also from this work
they beleive gravity doesn't originate from this universe. It "leaks" in from a parallel universe, this would explain why its so
weak!
none of this is fact; physics is a bunch of theories used to describe what we humans observe; then experiments devise to prove/disprove the
threory.
Personally I do not believe such a thing as time really exists. We only have a concept of time because we as humans have memories and can remember
stuff in the immediate past.
Consider what the world would be like without time. It would be like looking at a movie film frames, but not knowing/remembering about the preceding
frame. Everything will be as it is in the frame, nothing has been different so moving items would appear in the place as photographed in the
frame.
Furthemore if time travel existed, we would be innundated by visitors from the future - I am not aware of it happening.
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flak monkey
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| posted on 25/5/06 at 11:28 AM |
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Now heres a puzzle:
Do the rules of maths exist and we discover them?
Or do we make up the rules to match what we observe?
If the latter why do they happen to work so well in explaining a lot of what goes on?
Sera
http://www.motosera.com
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trogdor
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| posted on 25/5/06 at 12:02 PM |
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well the time travel that i had heard about requires u to build the machine first, as the messages are sent using the same machine in the future that
has been buillt. ie as soon as u switched it on, messages would appear that have been sent on the machine u had just switiched on.
but anyways yes all of this is just theories to explain all the things that we can't explain. i do find it all fasinating tho, especially
parallel universes. i watched the documentry on it again yesterday. was a good alternative to revision!
time is an interesting thing, especially as it can change without all this physics nonsense, the brain has a time perception area, this means that
time can pass quick, ie when u are enjoying urself. or real slow, like when sitting in lectures! so if its slow to u, what is it to everyone else?
time is just how u percieve it.
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skint scotsman
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| posted on 26/5/06 at 10:14 PM |
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*ala malibu advert*
i just want to build a sports car
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Peteff
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| posted on 27/5/06 at 08:38 AM |
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My theory.
Time was invented by Man to explain growing old. It's a relative thing like size. A lifetime to any mammal would be the same as a lifetime to a
human and include the same events, birth, death and the bit in between but the scale is different. When you're born, time begins and when you
die, time ends. You may all have your own theories on this like Einstein did and like to think there are ways to beat the system, but I haven't
heard of anyone who's done it yet and I won't be holding my breath till I do either.
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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robertst
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| posted on 27/5/06 at 11:01 AM |
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if we were dogs, or cats, and had a 6 million year evolutionary period like humans, it is possible that, as their lifetime is around 15 human years, a
day for us (cats or dogs) would be shorter than for humans.
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