Understanding through Discussion


Welcome! You are not logged in. [ Login ]
EvC Forum active members: 79 (8897 total)
Current session began: 
Page Loaded: 03-19-2019 9:19 PM
138 online now:
AZPaul3, dwise1, Minnemooseus (Adminnemooseus), ramoss (4 members, 134 visitors)
Chatting now:  Chat room empty
Newest Member: WookieeB
Post Volume:
Total: 848,460 Year: 3,497/19,786 Month: 492/1,087 Week: 82/212 Day: 12/31 Hour: 1/0


Thread  Details

Email This Thread
Newer Topic | Older Topic
  
Prev1234
5
Author Topic:   The Plausibility of Alien Life
DevilsAdvocate
Member (Idle past 1175 days)
Posts: 1548
Joined: 06-05-2008


Message 61 of 73 (496268)
01-27-2009 10:20 AM
Reply to: Message 58 by Agobot
01-27-2009 8:53 AM


That's what i want to know as well. Well see, i'll try to keep it short(i don't like long posts anyway).

Imagine you are carrying in your hands a very powerful laser torch. A laser torch so powerful that it could send a beam of visible light to Mars.

Actually this can already occur. Lasers in space have no distance limitation. We can already use a laser to measure the distance (range) to the moon (by essentially bouncing it off the moons surface). The only problem is that the light from the laser spreads out logarithmically in area the further in distance it reaches. So that when the beam hits the laser reflector on the moon, the area the photons from the laser hit is wider than what it was before it left the Earth. Since Mars is further away, this area hit by the photons from the laser cover even a larger area and are going to being absorbed by Mar's atmosphere. Therefore these photons will not bounce back and will not be detected by any Earth based light detection system.

You switch on your laser torch and you point it towards the sky and hold it steady. After a minute, the light will reach Mars.

It takes about 3 minutes for light to reach Mars from the Earth at the closest proximity between the two.

You look through your 2000x magnifying telescope and see that the beam has hit Mars. Then you sweep your hand and the ray goes all the way to the other end of the horizon.

What horizon? The horizon of the Earth?

What happens with the ray? It follows your hand and because light travels only in straight line, the light that shone Mars will have to move FTL to the other end of the horizon, which might be pointing to Jupiter for example. If it doesn't, then light will have to bend which is impossible as far as we know.

Um, no. Light cannot go faster than the speed of light. That is an oxymoronic statement. Light follows the shortest path between two points on the curvature of spacetime. If spacetime is warped because of gravity than it takes the shortest path which will make it seem to a static observer i.e. an astronomer looking through a telescope, that light bends. However, it is not light that is bending but it is the very fabric of spacetime itself due to gravity. The light is actually in multi-dimensional, Einsteinian (as opposed to Euclidian geometry) geometry taking the straightest and shortest path between two points.

Edited by DevilsAdvocate, : No reason given.


For me, it is far better to grasp the Universe as it really is than to persist in delusion, however satisfying and reassuring.
Dr. Carl Sagan
This message is a reply to:
 Message 58 by Agobot, posted 01-27-2009 8:53 AM Agobot has responded

Replies to this message:
 Message 64 by Agobot, posted 01-27-2009 1:01 PM DevilsAdvocate has not yet responded

Larni
Member
Posts: 3975
From: Liverpool
Joined: 09-16-2005


Message 62 of 73 (496284)
01-27-2009 12:46 PM
Reply to: Message 58 by Agobot
01-27-2009 8:53 AM


If you aim at Mars with a laser and it takes the fist photon 3 minutes to hit and then move your aim to Jupiter (say for example Jupiter in 3 light hours away) it will take the first photon 3 hours to arrive.

I think the idea you have in your head is a perfectly rigid bar 3 light minutes long that can poke Mars from Earth and then being move to poke something else at a similar distance, thus moving the point faster than the speed of light.

The energy required to move the bar through any amount of degrees would increase with the length and the perfect rigidity of the bar is a product of I don't know what engineering.

It would not happen.

Of course you may not be thinking this.


This message is a reply to:
 Message 58 by Agobot, posted 01-27-2009 8:53 AM Agobot has responded

Replies to this message:
 Message 63 by Agobot, posted 01-27-2009 12:59 PM Larni has responded

  
Agobot
Member (Idle past 3604 days)
Posts: 786
Joined: 12-16-2007


Message 63 of 73 (496287)
01-27-2009 12:59 PM
Reply to: Message 62 by Larni
01-27-2009 12:46 PM


Larni writes:

If you aim at Mars with a laser and it takes the fist photon 3 minutes to hit and then move your aim to Jupiter (say for example Jupiter in 3 light hours away) it will take the first photon 3 hours to arrive.

That's what i thought initially but i don't think this is the case any more. It's a little deeper than it looks at first sight.

Basically what you are saying means that light can bend and we know that light always follows a straigth line.
When you hold that torch and it's light is hitting Mars, the moment you move your hand light will stop to be emitted towards Mars. But that doesn't mean that a hypotetical person on Mars wouldn't see any more light. In fact, he would for another 3 minutes. And as you are moving your hand in some direction, light is either moving in a straight line FTL or it's moving not in a straight line.

Which one are we going to keep: That light can only move in straight line or that light can move FTL?


This message is a reply to:
 Message 62 by Larni, posted 01-27-2009 12:46 PM Larni has responded

Replies to this message:
 Message 65 by Larni, posted 01-27-2009 1:40 PM Agobot has responded
 Message 70 by Blue Jay, posted 01-27-2009 2:50 PM Agobot has not yet responded

  
Agobot
Member (Idle past 3604 days)
Posts: 786
Joined: 12-16-2007


Message 64 of 73 (496289)
01-27-2009 1:01 PM
Reply to: Message 61 by DevilsAdvocate
01-27-2009 10:20 AM


Sorry Devil's advocate, i have no idea what you are saying. Maybe you want to have a look at the link of Modulous to familirise yourself with where we are going:

http://www.physlink.com/education/askexperts/ae497.cfm


This message is a reply to:
 Message 61 by DevilsAdvocate, posted 01-27-2009 10:20 AM DevilsAdvocate has not yet responded

  
Larni
Member
Posts: 3975
From: Liverpool
Joined: 09-16-2005


Message 65 of 73 (496292)
01-27-2009 1:40 PM
Reply to: Message 63 by Agobot
01-27-2009 12:59 PM


The beam of light diffuses.

Imagine a stream of water firing out of a hose in free fall and vacuum.

Now slow down the camera; looks like a solid stream of water, right?

Now move the hose 45 degrease to the right.

What do you see?

That's what happens with a 'stream' of photons.


This message is a reply to:
 Message 63 by Agobot, posted 01-27-2009 12:59 PM Agobot has responded

Replies to this message:
 Message 66 by Agobot, posted 01-27-2009 1:51 PM Larni has responded

  
Agobot
Member (Idle past 3604 days)
Posts: 786
Joined: 12-16-2007


Message 66 of 73 (496293)
01-27-2009 1:51 PM
Reply to: Message 65 by Larni
01-27-2009 1:40 PM


Larni writes:

The beam of light diffuses.
Imagine a stream of water firing out of a hose in free fall and vacuum.

Now slow down the camera; looks like a solid stream of water, right?

Now move the hose 45 degrease to the right.

What do you see?

That's what happens with a 'stream' of photons

That's why i chose to use "laser torch" so that the light beam scattering effect would be negligeable. And I don't think light behaves like water coming from a hose. Light always moves in straight lines, that's a crucial point.


This message is a reply to:
 Message 65 by Larni, posted 01-27-2009 1:40 PM Larni has responded

Replies to this message:
 Message 67 by Larni, posted 01-27-2009 2:00 PM Agobot has responded

  
Larni
Member
Posts: 3975
From: Liverpool
Joined: 09-16-2005


Message 67 of 73 (496294)
01-27-2009 2:00 PM
Reply to: Message 66 by Agobot
01-27-2009 1:51 PM


And I don't think light behaves like water coming from a hose. Light always moves in straight lines, that's a crucial point.

That's why I stipulated free fall and a vacuum environment.

Over 3 light minutes the been will be massively diffuse because there will be not enough individual photons to 'paint' the target line of the beam.

You would get a line from Mars to Jupiter (say 3 light minutes apart) with maybe one photon per million miles (the numbers are doubtless wrong but I hope I'm explaining the principal).

This would trail along taking 3 hours to arrive.

I in no way argue that light bends in this instance. It moves in a straight line at the speed of light. Never faster.


This message is a reply to:
 Message 66 by Agobot, posted 01-27-2009 1:51 PM Agobot has responded

Replies to this message:
 Message 68 by Agobot, posted 01-27-2009 2:14 PM Larni has responded

  
Agobot
Member (Idle past 3604 days)
Posts: 786
Joined: 12-16-2007


Message 68 of 73 (496298)
01-27-2009 2:14 PM
Reply to: Message 67 by Larni
01-27-2009 2:00 PM


Larni writes:

That's why I stipulated free fall and a vacuum environment.

Over 3 light minutes the been will be massively diffuse because there will be not enough individual photons to 'paint' the target line of the beam.

No, there are trillions of trillions of them.

LArni writes:

You would get a line from Mars to Jupiter (say 3 light minutes apart) with maybe one photon per million miles (the numbers are doubtless wrong but I hope I'm explaining the principal).

This would trail along taking 3 hours to arrive.

I in no way argue that light bends in this instance. It moves in a straight line at the speed of light. Never faster.

But if you move your hand and the light trails behind your movement, someone watching your event with a telescope would see that light is following a curved path. That's impossible.

The whole explanation is more complicated than that and since we are offtopic and it's audacious to rack the mods even further, i'll conclude this with a quote from Richard Feynman about the properties of light:

"...there is also an amplitude for light to go faster (or slower) than the conventional speed of light. You found out in the last lecture that light doesn't go only in straight lines; now, you find out that it doesn't go only at the speed of light! It may surprise you that there is an amplitude for a photon to go at speeds faster or slower than the conventional speed, c." - Chapter 3, page 89 of Richard Feynman's book "QED".


This message is a reply to:
 Message 67 by Larni, posted 01-27-2009 2:00 PM Larni has responded

Replies to this message:
 Message 69 by Larni, posted 01-27-2009 2:34 PM Agobot has not yet responded

  
Larni
Member
Posts: 3975
From: Liverpool
Joined: 09-16-2005


Message 69 of 73 (496300)
01-27-2009 2:34 PM
Reply to: Message 68 by Agobot
01-27-2009 2:14 PM


No, there are trillions of trillions of them.

Could be. But the light would still take the same amount of time to reach the new target of the beam and all points in between.

But if you move your hand and the light trails behind your movement, someone watching your event with a telescope would see that light is following a curved path. That's impossible.

No they wouldn't: it's impossible.

Well, I still don't think just pointing a laser at another target somehow alters the speed of the beam but I guess I've reached the limit of my knowledge of physics and can't really do anything other than restate my point.

So I'd better leave it, too.

Edited by Larni, : Clarity.


This message is a reply to:
 Message 68 by Agobot, posted 01-27-2009 2:14 PM Agobot has not yet responded

  
Blue Jay
Member (Idle past 772 days)
Posts: 2843
From: You couldn't pronounce it with your mouthparts
Joined: 02-04-2008


Message 70 of 73 (496301)
01-27-2009 2:50 PM
Reply to: Message 63 by Agobot
01-27-2009 12:59 PM


Speed of Light?
Hi, Agobot.

Agobot writes:

Basically what you are saying means that light can bend and we know that light always follows a straigth line.

No. What Larni is saying is that a beam of light can bend without any individual photon traveling in a curved path. And, this is clearly true.

Why are you talking about this, again?


-Bluejay/Mantis/Thylacosmilus

Darwin loves you.


This message is a reply to:
 Message 63 by Agobot, posted 01-27-2009 12:59 PM Agobot has not yet responded

AdminNosy
Administrator
Posts: 4754
From: Vancouver, BC, Canada
Joined: 11-11-2003


Message 71 of 73 (496303)
01-27-2009 3:05 PM


Topic or thread closes
If you wish to keep discussing alien life you should get off the physics of light beams.

If you stay off topic the thread will be closed.


Buzsaw
Inactive Member


Message 72 of 73 (496365)
01-27-2009 10:00 PM
Reply to: Message 47 by Parasomnium
01-27-2009 2:39 AM


Re: (Anti)matter And Cosmological Intelligence
Parasomnium writes:

We do know what happens when matter and antimatter meet: they annihilate one another and are completely converted to energy according to Einstein's famous formula E=mc2.

Hi Parasomnium. I appreciate that you are still among us, though we don't agree on much. As I recall you have been an amiable and fair opponent to debate counterparts. :cool:

1. Isn't that essentially what I said, that we don't know? How do we know they annihilate one another, and what form of energy, etc.

2. To annihilate and to convert are two different processes. Imo, you can't have both but one or the other. If converted, as I surmised, we don't know, to what form of energy.

My point again was that perhaps they have similar properties to what the Bible describes as angel creatures which appear from the human eye to convert to a different energy.

--------------------------------------------------------------------------------

Edited by Buzsaw, : Expand Title


BUZSAW B 4 U 2 C Y BUZ SAW.
The immeasurable present eternally extends the infinite past and infinitely consumes the eternal future.
This message is a reply to:
 Message 47 by Parasomnium, posted 01-27-2009 2:39 AM Parasomnium has not yet responded

AdminNosy
Administrator
Posts: 4754
From: Vancouver, BC, Canada
Joined: 11-11-2003


Message 73 of 73 (496378)
01-27-2009 10:47 PM


Closed for a rest
Since Buz choose to continue the off topic discussion. This thread is closed. It may be reopened if there is interest in the actual topic.
Prev1234
5
Newer Topic | Older Topic
Jump to:


Copyright 2001-2018 by EvC Forum, All Rights Reserved

™ Version 4.0 Beta
Innovative software from Qwixotic © 2019