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Light through a vaccum?

B

BigToquex

Senior member
There was an article a while ago about some people firing a laser through a vaccum and it came out the other side before it even entered the vaccum.

Anyone remember this article?
 
ummm... sounds kind of shady... isnt space a vacuum anyway? So, sunlight reaches us before it leaves the sun?

and is it possible to get a better vacuum than space?
 
Originally posted by: BigToque
There was an article a while ago about some people firing a laser through a vaccum and it came out the other side before it even entered the vaccum.

Anyone remember this article?
Click to expand...

No. But that is not possible.
 
I know I'm not being stupid... I remember somone posting a link to the article here.

I just wish I could find it again.
 
It was a laser pulse fired through a super low pressure ionized cesium gas IIRC.

It doesn't actually go faster than light, it's all about phase waves and constructive/destructive interference that make it seem as though the wave went through faster than light. Radio waves do this cool effect in the ionosphere where they hit the ionized gas and they set up phase waves which go faster than light, but it's all due to interference patterns.

Throw a stone into a pond. You will see the initial outermost ring travelling outwards from the splash at a certain speed, and then you will also see waves inside the ring travelling outwards much faster than the initial wave, however, they can never "pass" that first outer wave. What's more, these waves aren't really caused by the rock, but they are just the resulting wave forms that are generated by the addition and subtraction of the peaks and troughs of the other waves that the stone caused. Same sort of thing with the radio waves in the ionosphere, and same sort of thing with the light and cesium.
 
Originally posted by: silverpig
It was a laser pulse fired through a super low pressure ionized cesium gas IIRC.

It doesn't actually go faster than light, it's all about phase waves and constructive/destructive interference that make it seem as though the wave went through faster than light. Radio waves do this cool effect in the ionosphere where they hit the ionized gas and they set up phase waves which go faster than light, but it's all due to interference patterns.

Throw a stone into a pond. You will see the initial outermost ring travelling outwards from the splash at a certain speed, and then you will also see waves inside the ring travelling outwards much faster than the initial wave, however, they can never "pass" that first outer wave. What's more, these waves aren't really caused by the rock, but they are just the resulting wave forms that are generated by the addition and subtraction of the peaks and troughs of the other waves that the stone caused. Same sort of thing with the radio waves in the ionosphere, and same sort of thing with the light and cesium.
Click to expand...

Score

 
Originally posted by: silverpig
It was a laser pulse fired through a super low pressure ionized cesium gas IIRC.

It doesn't actually go faster than light, it's all about phase waves and constructive/destructive interference that make it seem as though the wave went through faster than light. Radio waves do this cool effect in the ionosphere where they hit the ionized gas and they set up phase waves which go faster than light, but it's all due to interference patterns.

Throw a stone into a pond. You will see the initial outermost ring travelling outwards from the splash at a certain speed, and then you will also see waves inside the ring travelling outwards much faster than the initial wave, however, they can never "pass" that first outer wave. What's more, these waves aren't really caused by the rock, but they are just the resulting wave forms that are generated by the addition and subtraction of the peaks and troughs of the other waves that the stone caused. Same sort of thing with the radio waves in the ionosphere, and same sort of thing with the light and cesium.
Click to expand...

you know..um...i had this science project and...um...was busy this week....umm..could you....um...
 
Originally posted by: silverpig
It was a laser pulse fired through a super low pressure ionized cesium gas IIRC.

It doesn't actually go faster than light, it's all about phase waves and constructive/destructive interference that make it seem as though the wave went through faster than light. Radio waves do this cool effect in the ionosphere where they hit the ionized gas and they set up phase waves which go faster than light, but it's all due to interference patterns.

Throw a stone into a pond. You will see the initial outermost ring travelling outwards from the splash at a certain speed, and then you will also see waves inside the ring travelling outwards much faster than the initial wave, however, they can never "pass" that first outer wave. What's more, these waves aren't really caused by the rock, but they are just the resulting wave forms that are generated by the addition and subtraction of the peaks and troughs of the other waves that the stone caused. Same sort of thing with the radio waves in the ionosphere, and same sort of thing with the light and cesium.
Click to expand...
Yep. It's called superluminal light. Although you can cause a wave to travel faster than light, you cannot convey any information that way. As soon as you try, the velocity will always be less than c. This is because of the difference in group and phase velocities. While the phase velocity can exceed c, the group velocity (which is what you're dealing with anytime you modulate a signal) never can.
 
Originally posted by: Heisenberg
Originally posted by: silverpig
It was a laser pulse fired through a super low pressure ionized cesium gas IIRC.

It doesn't actually go faster than light, it's all about phase waves and constructive/destructive interference that make it seem as though the wave went through faster than light. Radio waves do this cool effect in the ionosphere where they hit the ionized gas and they set up phase waves which go faster than light, but it's all due to interference patterns.

Throw a stone into a pond. You will see the initial outermost ring travelling outwards from the splash at a certain speed, and then you will also see waves inside the ring travelling outwards much faster than the initial wave, however, they can never "pass" that first outer wave. What's more, these waves aren't really caused by the rock, but they are just the resulting wave forms that are generated by the addition and subtraction of the peaks and troughs of the other waves that the stone caused. Same sort of thing with the radio waves in the ionosphere, and same sort of thing with the light and cesium.
Click to expand...
Yep. It's called superluminal light. Although you can cause a wave to travel faster than light, you cannot convey any information that way. As soon as you try, the velocity will always be less than c. This is because of the difference in group and phase velocities. While the phase velocity can exceed c, the group velocity (which is what you're dealing with anytime you modulate a signal) never can.
Click to expand...


Dude, are you Werner Heisenberg?

😀
 
Originally posted by: Heisenberg
Originally posted by: silverpig
It was a laser pulse fired through a super low pressure ionized cesium gas IIRC.

It doesn't actually go faster than light, it's all about phase waves and constructive/destructive interference that make it seem as though the wave went through faster than light. Radio waves do this cool effect in the ionosphere where they hit the ionized gas and they set up phase waves which go faster than light, but it's all due to interference patterns.

Throw a stone into a pond. You will see the initial outermost ring travelling outwards from the splash at a certain speed, and then you will also see waves inside the ring travelling outwards much faster than the initial wave, however, they can never "pass" that first outer wave. What's more, these waves aren't really caused by the rock, but they are just the resulting wave forms that are generated by the addition and subtraction of the peaks and troughs of the other waves that the stone caused. Same sort of thing with the radio waves in the ionosphere, and same sort of thing with the light and cesium.
Click to expand...
Yep. It's called superluminal light. Although you can cause a wave to travel faster than light, you cannot convey any information that way. As soon as you try, the velocity will always be less than c. This is because of the difference in group and phase velocities. While the phase velocity can exceed c, the group velocity (which is what you're dealing with anytime you modulate a signal) never can.
Click to expand...

You haven't, by any chance, read a book called "Perfect Symmetry" by Heigels have you? 😀
 
Originally posted by: bolomite
Originally posted by: Heisenberg
Originally posted by: silverpig
It was a laser pulse fired through a super low pressure ionized cesium gas IIRC.

It doesn't actually go faster than light, it's all about phase waves and constructive/destructive interference that make it seem as though the wave went through faster than light. Radio waves do this cool effect in the ionosphere where they hit the ionized gas and they set up phase waves which go faster than light, but it's all due to interference patterns.

Throw a stone into a pond. You will see the initial outermost ring travelling outwards from the splash at a certain speed, and then you will also see waves inside the ring travelling outwards much faster than the initial wave, however, they can never "pass" that first outer wave. What's more, these waves aren't really caused by the rock, but they are just the resulting wave forms that are generated by the addition and subtraction of the peaks and troughs of the other waves that the stone caused. Same sort of thing with the radio waves in the ionosphere, and same sort of thing with the light and cesium.
Click to expand...
Yep. It's called superluminal light. Although you can cause a wave to travel faster than light, you cannot convey any information that way. As soon as you try, the velocity will always be less than c. This is because of the difference in group and phase velocities. While the phase velocity can exceed c, the group velocity (which is what you're dealing with anytime you modulate a signal) never can.
Click to expand...


Dude, are you Werner Heisenberg?

😀
Click to expand...

<---- hoping to soak up some of the second hand science knowledge... man you nerds are awesome! 😀
 
Originally posted by: Goosemaster
Originally posted by: silverpig
It was a laser pulse fired through a super low pressure ionized cesium gas IIRC.

It doesn't actually go faster than light, it's all about phase waves and constructive/destructive interference that make it seem as though the wave went through faster than light. Radio waves do this cool effect in the ionosphere where they hit the ionized gas and they set up phase waves which go faster than light, but it's all due to interference patterns.

Throw a stone into a pond. You will see the initial outermost ring travelling outwards from the splash at a certain speed, and then you will also see waves inside the ring travelling outwards much faster than the initial wave, however, they can never "pass" that first outer wave. What's more, these waves aren't really caused by the rock, but they are just the resulting wave forms that are generated by the addition and subtraction of the peaks and troughs of the other waves that the stone caused. Same sort of thing with the radio waves in the ionosphere, and same sort of thing with the light and cesium.
Click to expand...

you know..um...i had this science project and...um...was busy this week....umm..could you....um...
Click to expand...


<--- astrophysics major 😉
 
Dude, are you Werner Heisenberg?
Click to expand...
Nope, I'm just uncreative with my nick choice, so I chose one I see a lot. 😉

You haven't, by any chance, read a book called "Perfect Symmetry" by Heigels have you?
Click to expand...
No. You have a link? I searched amazon but couldn't find it. 🙂

<------ physics nerd...err grad student
 
Originally posted by: Heisenberg
Dude, are you Werner Heisenberg?
Click to expand...
Nope, I'm just uncreative with my nick choice, so I chose one I see a lot. 😉

You haven't, by any chance, read a book called "Perfect Symmetry" by Heigels have you?
Click to expand...
No. You have a link? I searched amazon but couldn't find it. 🙂

<------ physics nerd...err grad student
Click to expand...

A guy I work with lent it to me. Ha, but come to think of it, that's not even the book I was thinking about. He gave me two and I've been jumping back and forth between the two.

The one I should have mentioned is called "Faster than Light" and the author escapes me right now.

Anyways, in FTL, the guy talks about different tricks to make things go faster than light, and there was an entire chapter on phase waves and stuff like that.

"Perfect Symmetry" is a longer book, and so far it's a nice laymans review of my first 2 years of physics and astronomy at university. It's a really nice book.


The only problem though is both books were written in the mid 80's, so they are a bit dated... but most of what they talk about deals with Einstein, so that's 1920s stuff.
 
Originally posted by: MartyTheManiak
my IQ went up 5 points just reading this thread, thanks silverpig!

😉
Click to expand...

And to think they actually kicked me out of university... 🙂


(i'm back in though) 😀
 
Originally posted by: silverpig
A guy I work with lent it to me. Ha, but come to think of it, that's not even the book I was thinking about. He gave me two and I've been jumping back and forth between the two.

The one I should have mentioned is called "Faster than Light" and the author escapes me right now.

Anyways, in FTL, the guy talks about different tricks to make things go faster than light, and there was an entire chapter on phase waves and stuff like that.

"Perfect Symmetry" is a longer book, and so far it's a nice laymans review of my first 2 years of physics and astronomy at university. It's a really nice book.


The only problem though is both books were written in the mid 80's, so they are a bit dated... but most of what they talk about deals with Einstein, so that's 1920s stuff.
Click to expand...
Ah. They sound like good books. My main sources of info are just classes I've taken. A friend of mine is involved in some subluminal light research (they've stopped light altogether IIRC), so I also try to pick what I can from him. It's a really cool subject.
 
Yeah. I find you learn some cool stuff in class, but all the really neat stuff I've learned has come from books, magazines, other people...
 
Originally posted by: Heisenberg
Originally posted by: silverpig
A guy I work with lent it to me. Ha, but come to think of it, that's not even the book I was thinking about. He gave me two and I've been jumping back and forth between the two.

The one I should have mentioned is called "Faster than Light" and the author escapes me right now.

Anyways, in FTL, the guy talks about different tricks to make things go faster than light, and there was an entire chapter on phase waves and stuff like that.

"Perfect Symmetry" is a longer book, and so far it's a nice laymans review of my first 2 years of physics and astronomy at university. It's a really nice book.


The only problem though is both books were written in the mid 80's, so they are a bit dated... but most of what they talk about deals with Einstein, so that's 1920s stuff.
Click to expand...
Ah. They sound like good books. My main sources of info are just classes I've taken. A friend of mine is involved in some subluminal light research (they've stopped light altogether IIRC), so I also try to pick what I can from him. It's a really cool subject.
Click to expand...

I have seen them stopping light, well it slows down to a crawl. It's called optical molases (sp?). Kind of cool stuff.

 
Originally posted by: MartyTheManiak
my IQ went up 5 points just reading this thread, thanks silverpig!

😉
Click to expand...

no kidding. This thread belongs in HT. The discussions that go on there are INSANE!
 
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