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Author Topic:   This has bothered me for ages! (re: Travel faster than the speed of light)
Trixie
Member (Idle past 2095 days)
Posts: 1011
From: Edinburgh
Joined: 01-03-2004


Message 1 of 33 (245024)
09-19-2005 9:03 PM


I have no idea if anyone would want to have a go at this. It's a hypothetical, nothing to do with evolution or creation, but I can't think of a better place to pose the question.

For this we have to make a few suppositions. Suppose we could travel faster than the speed of light. Also suppose we had found a way to arrive at our destination at the speed of light without turning our destination planet into a heap of rubble and our spacecraft into particles. Oh, and without killing our observer on the destination planet, just beside the landing site.

What would our observer see?

Would the observer see the craft on the launch pad, then the craft on the launch pad and also on the landing site, without yet having seen the journey? Would the observer then see the journey in reverse? If the distance was short enough and the speed fast enough, would the reversing image finally get to the launch pad, whereupon both these images would disappear and we would be left with just the actual craft at the landing site?

If the speed was a bit slower (but still faster than light) and the distance great enough, when the reverse journey happens, would the image at the launch pad would start it's journey as well? Would the two images merge and disappear somewhere? Is the point they merge at dependent on the speed and the distance travelled?

Can anyone tell me if I've got this totally wrong? I'm certainly not a physicist, so don't blind me with physicist terminology.

To Admin ; God knows where this would go, possibly Coffee House.

{Cranky Adminnemooseus added the "(re: Travel faster than the speed of light)" part to the otherwise pretty worthless topic title}

This message has been edited by Adminnemooseus, 09-20-2005 12:01 PM


Replies to this message:
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AdminAsgara
Administrator (Idle past 691 days)
Posts: 2073
From: The Universe
Joined: 10-11-2003


Message 2 of 33 (245027)
09-19-2005 9:13 PM


Thread moved here from the Proposed New Topics forum.

Though I shouldn't move this...'cuz now I'm not going to be able to sleep tonight either...thanks Trix

This message has been edited by AdminAsgara, 09-19-2005 08:14 PM


  
Coragyps
Member
Posts: 5428
From: Snyder, Texas, USA
Joined: 11-12-2002
Member Rating: 5.3


Message 3 of 33 (245042)
09-19-2005 10:38 PM
Reply to: Message 1 by Trixie
09-19-2005 9:03 PM


I think you've actually hit the nail on the head, Trixie. Your puzzle may be the "why" in "why can't we go faster than light?" It's not because of physics. It's because our heads would implode thinking about what we just did!

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RAZD
Member
Posts: 20487
From: the other end of the sidewalk
Joined: 03-14-2004
Member Rating: 3.5


Message 4 of 33 (245062)
09-19-2005 11:35 PM
Reply to: Message 1 by Trixie
09-19-2005 9:03 PM


If the speed was a bit slower (but still faster than light) and the distance great enough,

let's say that the distance is just right for the image of the landing to reach the observer at the moment that they observe the craft taking off.

I would think there would be a solid appearing bridge from one location to the other in that instant.


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Lammy
Member
Posts: 3616
From: Chicago
Joined: 03-29-2004


Message 5 of 33 (245066)
09-20-2005 12:05 AM
Reply to: Message 1 by Trixie
09-19-2005 9:03 PM


Ok, let us do it your way.

quote:
For this we have to make a few suppositions. Suppose we could travel faster than the speed of light. Also suppose we had found a way to arrive at our destination at the speed of light without turning our destination planet into a heap of rubble and our spacecraft into particles. Oh, and without killing our observer on the destination planet, just beside the landing site.



The collisions of the trillions and trillions of photon particles into you per nano-nano-nano-nano-nano-second would fry your ass.

This message has been edited by GAW-Snow, 09-20-2005 12:06 AM


This message is a reply to:
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Thor
Member (Idle past 4299 days)
Posts: 148
From: Sydney, Australia
Joined: 12-20-2004


Message 6 of 33 (245070)
09-20-2005 12:15 AM
Reply to: Message 1 by Trixie
09-19-2005 9:03 PM


Hmmm…food for thought, I'll take a shot. I’m thinking along these lines:

Lets say the trip is from Planet A to Planet B, the distance being 10 light hours. Say the craft could travel at twice the speed of light. 5 hours into the trip, the observer on B would see the craft on the pad because it is right there and would be immediately visible. If the observer then looked through some kick-ass telescope and looked at A, they would see the craft on the launch pad because the visible light from A is 10 hours old.

As for the journey of the craft itself, light from later parts of the journey would be visible to the observer before earlier parts, because it’s starting from a point closer to the observer and has a head start because the craft is moving faster than light. Light given off earlier in the trip is still lagging behind at lightspeed x1. I guess I would conclude from all that that you actually would see the journey in reverse from the landing pad to the launch pad. Or more precisely, from the landing pad to the point where the craft initially exceeded light speed. I guess it would sort of go like this:

You’d see the craft going backwards from the landing pad.
At a point not far from the launch site, the craft would suddenly disappear and instantaneously reappear on the launchpad.
You’d see the launch.
You’d see the craft taking off and accelerating, then disappear.
All the while, the craft has been visible sitting on the landing pad.

Ok, now I think I’m going to go and have a lie-down.:confused:


On the 7th day, God was arrested.

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cavediver
Member (Idle past 2032 days)
Posts: 4129
From: UK
Joined: 06-16-2005


Message 7 of 33 (245086)
09-20-2005 5:09 AM
Reply to: Message 4 by RAZD
09-19-2005 11:35 PM


I would think there would be a solid appearing bridge from one location to the other in that instant.

I'm inpressed :)

But wait, you don't believe GR/SR ;)


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cavediver
Member (Idle past 2032 days)
Posts: 4129
From: UK
Joined: 06-16-2005


Message 8 of 33 (245095)
09-20-2005 6:24 AM
Reply to: Message 1 by Trixie
09-19-2005 9:03 PM


Hi Trixie! Oh dear, where to start ;) When we say you can't go faster than light, why can't people just leave it at that???

Ok, forget all the frying yourself or the spacecraft or the planet or whatever. It's irrelevant to the discussion.

Given that at the speed of light, it takes zero time to arrive at your destination, how do you intend to accelerate to beyond the speed of light? Given that at the speed of light, the distance between you and your destination is zero, why would you even try?

What you have to understand is that the speed of light is just a speed limit on the perceived velocity of an object, not on the speed of the object itself. You yourself can travel at any speed you like up to infinte speed, if you are defining speed as distance travelled over time taken. Alpha C is ~4lyrs away. I cn get there in 8 yrs, so have speed .5c. I can get there in 4 yrs so have speed c. I can get there in 1 day, so have speed ~1460c.

RAZD had it correct. What you are trying to describe is no longer an object travelling, but an extended physical object spanning two distant points. But it is an object that at some point blinks into existance and then at some later time blinks out of existence. Not a concept that makes a lot of sense.

The speed of light is a barrier between concepts of objects evolving through time, and objects that are physically extended. It's a lot deeper than you imagine...

Of coures, you can repeat your idea but instead of trying to travel superluminary, you can employ a wormhole to "teleport" to your destination. You will then be able to see yourself back at your origin before taking the trip, and all such fun. If you travel in such a way that you arrive at a destination before a light-ray, you have a time-machine. Simple as that.


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Chiroptera
Member
Posts: 6856
From: Oklahoma
Joined: 09-28-2003
Member Rating: 6.0


Message 9 of 33 (245115)
09-20-2005 8:20 AM
Reply to: Message 1 by Trixie
09-19-2005 9:03 PM


Short answer
No one knows. The present laws of physics do not allow for faster than light travel, at all. Therefore, if faster-that-light travel is possible, then that means that our present laws of physics are not complete -- we need a new formulation of the laws of physics. But right now, we don't know what they would be. They would have to agree with ordinary relativity at subluminal speeds, but we have no way of knowing what they would predict for superluminal speeds.

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Adminnemooseus
Director
Posts: 3912
Joined: 09-26-2002


Message 10 of 33 (245159)
09-20-2005 12:04 PM


Topic title modified into something that means something
This topic had but one of the worthless topic titles that are lurking out there.

People - The topic title should give information about the topics theme.

Adminnemooseus


Replies to this message:
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Trixie
Member (Idle past 2095 days)
Posts: 1011
From: Edinburgh
Joined: 01-03-2004


Message 11 of 33 (245218)
09-20-2005 3:23 PM
Reply to: Message 10 by Adminnemooseus
09-20-2005 12:04 PM


Re: Topic title modified into something that means something
Sorry Adminnemooseus. I really didn't know what to call it and it was about 2am during a sleepless night. It won't happen again.

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RAZD
Member
Posts: 20487
From: the other end of the sidewalk
Joined: 03-14-2004
Member Rating: 3.5


Message 12 of 33 (245336)
09-20-2005 8:08 PM
Reply to: Message 11 by Trixie
09-20-2005 3:23 PM


Re: Topic title modified into something that means something
Good

I'm glad you'll sleep better now :laugh:


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Scaryfish
Junior Member (Idle past 4679 days)
Posts: 30
From: New Zealand
Joined: 12-06-2004


Message 13 of 33 (245380)
09-20-2005 10:43 PM
Reply to: Message 1 by Trixie
09-19-2005 9:03 PM


Hmm.. I think we'd see a "photonic boom" - a bright flash, the light equivalent to a sonic boom. You know how light travels slower through glass for instance? And even slower through other materials? I vaguely remember an article somewhere about light being passed through glass (or something) at the same time as a very high speed neutron was shot through it (which doesn't slow down much at all), and it produced little flashes of light.

That's just my guess anyway. I'm not a physicist.


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Funkaloyd
Inactive Member


Message 14 of 33 (245423)
09-21-2005 7:58 AM


Something slightly less complicated which I may as well ask here:

Suppose that the gravitational constant is much stronger, the speed of light is faster, and the Universe is much smaller and closed. Or alternatively, suppose that light follows the surface of the Earth, essentially making the Universe flat.

If I look any direction, failing any obstructions, I'll see the back of my head, no? Would the "edge" of the Universe then appear to be just a huge blur of dark brown hair?


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cavediver
Member (Idle past 2032 days)
Posts: 4129
From: UK
Joined: 06-16-2005


Message 15 of 33 (245429)
09-21-2005 8:21 AM
Reply to: Message 14 by Funkaloyd
09-21-2005 7:58 AM


Would the "edge" of the Universe then appear to be just a huge blur of dark brown hair?

Yep :) And if you stand the right distance from a black hole (3 times its mass in geometrical units) and look left or right, you will see an inifnite number of yourself disappearing into the distance! You can do fun thing with gravity...

BUT, a normal closed universe will always collapse before your light has time to travel all of the way around. In an accelerating closed universe, the universe will out run your light, so again it won't work. It works best in the Einstein Static Universe (ESU), where there is no expansion or contraction.


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