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Author Topic: Why is light so slow?  (Read 13962 times)

Offline Geezer

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Why is light so slow?
« on: 08/12/2011 18:56:42 »
I think we tend to think of light as travelling incredibly fast. However, as anyone who does anything with electronics will tell you, it's really quite annoyingly slow. Heck, it's not even 1000 times faster than commercial airliners. It's almost as if spacetime was a big blob of treacle (molasses).

Why does it have to be so slow?


 

Offline syhprum

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Why is light so slow?
« Reply #1 on: 08/12/2011 20:26:33 »
Right you have us all on tenterhooks now spill the beans.
I worked in electronics for many years and never had any problem with light moving too slow.
 

Offline Geezer

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Why is light so slow?
« Reply #2 on: 08/12/2011 20:47:03 »
Right you have us all on tenterhooks now spill the beans.
I worked in electronics for many years and never had any problem with light moving too slow.

Well, if light travelled a lot faster, presumably electronic signals would propagate a lot faster too.
 

Offline JP

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Why is light so slow?
« Reply #3 on: 08/12/2011 21:13:47 »
Heck, it's not even 1000 times faster than commercial airliners.

I think you're off by a few orders of magnitude.  Sound ~3E2 m/s, light ~ 3E8 m/s, so light ~ 3E6 faster than sound, and most commercial airliners go slower than the speed of sound.
 

Offline Geezer

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Why is light so slow?
« Reply #4 on: 08/12/2011 21:21:32 »
Heck, it's not even 1000 times faster than commercial airliners.

I think you're off by a few orders of magnitude.  Sound ~3E2 m/s, light ~ 3E8 m/s, so light ~ 3E6 faster than sound, and most commercial airliners go slower than the speed of sound.

[:I] Oops! Got me hours and me seconds mixed up! (km/sec v km/hr f=3600)

Anyway, it's still not ALL that fast.

 

Offline CliffordK

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Why is light so slow?
« Reply #5 on: 08/12/2011 21:22:49 »
Heck, it's not even 1000 times faster than commercial airliners.

What airline have you been flying on?

Mach 1 is 768 mph (although it varies with altitude).
The Speed of Light is 671 Million MPH.

Or...  about Mach 1 MILLION.

If you had 10G acceleration, (98 m/s2), it would take:
299,792,458 m/s / 98 m/s2 / ((60 s/m)*(60 m/h)*(24 h/d))
And, it would take you about 35 days of continuous Mach 10 acceleration to achieve the speed of light.
 

Offline JP

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Why is light so slow?
« Reply #6 on: 08/12/2011 21:27:19 »
It strikes me that if you devise some electronic device that runs at roughly the speed of light, its always going to be limited by the speed of light, not matter if it were faster or not.  So long as there is a speed limit, you'll bump up against it.
 

Offline CliffordK

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Why is light so slow?
« Reply #7 on: 08/12/2011 21:53:50 »
It strikes me that if you devise some electronic device that runs at roughly the speed of light, its always going to be limited by the speed of light, not matter if it were faster or not.  So long as there is a speed limit, you'll bump up against it.

Of course, there are many ways to phrase the question.

Why are atoms so HUGE?

Hydrogen is about 10-10m in diameter.
A proton is about 1.75 x 10-15m in diameter.

So, if atoms were the size of protons, then you could make your electronics much smaller, and about 10,000 times faster.  So much for nano-technology.

However,
We live in the physical universe.
 

Offline yor_on

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Why is light so slow?
« Reply #8 on: 08/12/2011 22:17:58 »
I kind of enjoyed that first definition Geezer. It reminded me favorably of Terry Pratchett, who used some similar definitions.

"Light thinks it travels faster than anything but it is wrong. No matter how fast light travels, it finds the darkness has always got there first, and is waiting for it"

I wonder if Mark Twain ever wrote about light?
=

Can't withhold this one, also from Terry.

"It is often said that before you die your life passes before your eyes. It is in fact true. It's called living."
« Last Edit: 08/12/2011 22:20:22 by yor_on »
 

Offline Geezer

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Why is light so slow?
« Reply #9 on: 08/12/2011 23:34:44 »
Er well, see, light only manages to travel about 100mm in one nanosecond, and electronic signals often only manage about one third of that, so they only travel about 30mm in one nanosecond. That means all the propagation delays have to be accounted for in high speed digital systems.

Sometimes you simply can't get from here to there fast enough. Now, if we could only get light to go a bit faster......
 

Offline CliffordK

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Why is light so slow?
« Reply #10 on: 09/12/2011 00:44:06 »
Sometimes you simply can't get from here to there fast enough. Now, if we could only get light to go a bit faster......
You could try to design the first Neutrino Computer  ;)

But, I imagine the design of such a machine would be more complicated, and not give you any true benefit.

What is happening is both making everything smaller, as well as making single chips far more complex.

The future of computers is likely to move towards single-chip computers, or single IC computers.  At least combining the Memory and CPU into a single device. 

Another thing that will likely come into play is the use of more dedicated sub-processors.  For example, with SCSI, most of the processing is offloaded to the SCSI controller.  I'm always cussing about my USB drives.  Frequently when I try a big dump from my hard drive to a USB device, it will bring the whole computer to a standstill.  There is no need for that to happen, but many computer specs fail to mention device throughput.
 

Offline syhprum

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Why is light so slow?
« Reply #11 on: 09/12/2011 05:48:23 »
I have a SCSI board in my computer to feed my olde worlde HP scanner but it will only work with a 32 bit system.
I grew up with SCSI and like it but it seems to have fallen out of favour.
 

Offline CliffordK

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Why is light so slow?
« Reply #12 on: 09/12/2011 05:53:45 »
I have a SCSI board in my computer to feed my olde worlde HP scanner but it will only work with a 32 bit system.
I grew up with SCSI and like it but it seems to have fallen out of favour.

SCSI is still used a lot in servers, and the hot-pluggable SCSI RAID systems are pretty sweet.

Unfortunately, it remains quite expensive, and for servers, oddly, it is running a few years behind desktop systems for drive capacity.
 

Offline MikeS

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Why is light so slow?
« Reply #13 on: 09/12/2011 07:54:08 »
Why is light so slow?

From its own 'point of view' it travels instantaneously so does not experience time.  We know that gravity dilates time and that space-time is curved or warped.  I imagine that 'curvature' is what slows the speed of light from instantaneous in its 'frame' to a finite speed in any other 'frame'.  That curvature is what we call time.
 

Offline Don_1

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Why is light so slow?
« Reply #14 on: 09/12/2011 09:41:59 »
Heck, it's not even 1000 times faster than commercial airliners.

What airline have you been flying on?


Not this one.
 

Offline CliffordK

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Why is light so slow?
« Reply #15 on: 11/12/2011 08:53:25 »
Ahh, I found it.

The Geezer Light
Quote
Researchers have succeeded in reducing the speed of light in a Bose-Einstein condensate to 38 MPH (61 km/h)

At that speed, you could outrun your Pinto's headlights!!!
 

Offline Bill S

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Why is light so slow?
« Reply #16 on: 12/12/2011 20:48:40 »
Quote
speed of light in a vacuum, i.e., 186,000 MPH [300,000 km/h].

Its not just Geezer who gets his hours and seconds mixed up. ::)

 

Offline neilep

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Why is light so slow?
« Reply #17 on: 12/12/2011 21:07:00 »
As a firm believer in empirical study I stuck a small torch on a snail.....Observed it for five minutes !

Conclusion. This light moved very slowly.

Glad I could help !
 

Offline CliffordK

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Why is light so slow?
« Reply #18 on: 12/12/2011 22:36:02 »
Quote
speed of light in a vacuum, i.e., 186,000 MPH [300,000 km/h].
Its not just Geezer who gets his hours and seconds mixed up. ::)
Oh,
I see, that came from the article that I had quoted above on the Bose-Einstein Condensate.
Good Catch!!

So, then one must ask if their other units are correct.
 

Offline MikeS

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Why is light so slow?
« Reply #19 on: 13/12/2011 07:25:25 »
neilep

Did the snail floresc?
 

Offline Geezer

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Why is light so slow?
« Reply #20 on: 13/12/2011 08:17:45 »
Quote
speed of light in a vacuum, i.e., 186,000 MPH [300,000 km/h].

Its not just Geezer who gets his hours and seconds mixed up. ::)



Well, there you are then. It's obvious that "c" is greatly overrated.

(Thanks Bill!)
 

Offline CliffordK

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Why is light so slow?
« Reply #21 on: 13/12/2011 08:20:26 »
neilep

Did the snail floresc?

Only the transgenic snails...

Those crossed with fireflies give a new meaning to the speed of light!!!
 

Offline Nizzle

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Why is light so slow?
« Reply #22 on: 13/12/2011 08:42:59 »
"c" is something weird isn't it. It's measured in m/s, but at the speed of light, time stands still, so s cannot be other than "0" and we all know that you shouldn't divide by "0". :p


 

Offline imatfaal

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Why is light so slow?
« Reply #23 on: 13/12/2011 11:26:10 »
"c" is something weird isn't it. It's measured in m/s, but at the speed of light, time stands still, so s cannot be other than "0" and we all know that you shouldn't divide by "0". :p

Niz - you cannot extend Special Relativity to the local frame of reference of light, we just do not know what happens at the speed of light; massive particles do not go as fast as the speed of light (gran sasso excepted) - and those things that do are weird massless particles (photon, graviton, gluon).  we just cannot say that time is frozen or stopped for photons
 

Offline Nizzle

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Why is light so slow?
« Reply #24 on: 13/12/2011 13:53:22 »
Maybe I should be less subtle with jokes and use a capital P in my smileys at the end :P
 

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Why is light so slow?
« Reply #24 on: 13/12/2011 13:53:22 »

 

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