Using light as a barrier to block people without grilling them
Clash Royale CLAN TAG#URR8PPP
$begingroup$
We know that light exerts pressure upon matter.
I'm imagining a hallway where an intense light source on one end shines towards the other end. The goal is to have the beam of light exert so much pressure that a human being cannot enter (or reach the end of) the hallway. Of course, we only want to deter the human, not to burn them to a crisp.
Would this be realistic?
science-based reality-check light radiation
edited Jan 15 at 5:11
Cyn
6,52911037
asked Jan 15 at 3:27
user60406user60406
7913
$endgroup$
|
show 10 more comments
$begingroup$
We know that light exerts pressure upon matter.
I'm imagining a hallway where an intense light source on one end shines towards the other end. The goal is to have the beam of light exert so much pressure that a human being cannot enter (or reach the end of) the hallway. Of course, we only want to deter the human, not to burn them to a crisp.
Would this be realistic?
science-based reality-check light radiation
edited Jan 15 at 5:11
Cyn
6,52911037
asked Jan 15 at 3:27
user60406user60406
7913
$endgroup$
15
$begingroup$
Naw, fam. I'm not sure what the math looks like (someone will draft that and put it into an answer, I'm sure), but that would definitely kill the person you are trying to repel.
$endgroup$
– user49466
Jan 15 at 4:14
7
$begingroup$
I have a different idea which might be useful to you. The light is just a distraction, a laser pointer of sorts which shows that defenses are working. Strong enough to blind unwary person and hiding the true defenses: giant fans blowing air in constant stream and doing pressure that way.
$endgroup$
– jo1storm
Jan 15 at 9:53
6
$begingroup$
Randall Munroe of XKCD fame has answered what’s basically the same question: what-if.xkcd.com/87
$endgroup$
– Mike Scott
Jan 15 at 10:45
2
$begingroup$
The closest you are going to get is the microwave area denial system, which has low risk of deep tissue injury instead burning only the skin. Most people flee before they are injured. en.wikipedia.org/wiki/Active_Denial_System
$endgroup$
– John
Jan 15 at 14:27
3
$begingroup$
Keep a lid on and make sure there is enough steam, this should make sure you steam them instead of grilling them... oh wait, this is wb not cooking....
$endgroup$
– rackandboneman
Jan 15 at 16:52
|
show 10 more comments
$begingroup$
We know that light exerts pressure upon matter.
I'm imagining a hallway where an intense light source on one end shines towards the other end. The goal is to have the beam of light exert so much pressure that a human being cannot enter (or reach the end of) the hallway. Of course, we only want to deter the human, not to burn them to a crisp.
Would this be realistic?
science-based reality-check light radiation
edited Jan 15 at 5:11
Cyn
6,52911037
asked Jan 15 at 3:27
user60406user60406
7913
$endgroup$
We know that light exerts pressure upon matter.
I'm imagining a hallway where an intense light source on one end shines towards the other end. The goal is to have the beam of light exert so much pressure that a human being cannot enter (or reach the end of) the hallway. Of course, we only want to deter the human, not to burn them to a crisp.
Would this be realistic?
science-based reality-check light radiation
science-based reality-check light radiation
edited Jan 15 at 5:11
Cyn
6,52911037
asked Jan 15 at 3:27
user60406user60406
7913
edited Jan 15 at 5:11
Cyn
6,52911037
asked Jan 15 at 3:27
user60406user60406
7913
edited Jan 15 at 5:11
Cyn
6,52911037
edited Jan 15 at 5:11
Cyn
6,52911037
edited Jan 15 at 5:11
Cyn
6,52911037
6,52911037
asked Jan 15 at 3:27
user60406user60406
7913
asked Jan 15 at 3:27
user60406user60406
7913
asked Jan 15 at 3:27
user60406user60406
7913
7913
15
$begingroup$
Naw, fam. I'm not sure what the math looks like (someone will draft that and put it into an answer, I'm sure), but that would definitely kill the person you are trying to repel.
$endgroup$
– user49466
Jan 15 at 4:14
7
$begingroup$
I have a different idea which might be useful to you. The light is just a distraction, a laser pointer of sorts which shows that defenses are working. Strong enough to blind unwary person and hiding the true defenses: giant fans blowing air in constant stream and doing pressure that way.
$endgroup$
– jo1storm
Jan 15 at 9:53
6
$begingroup$
Randall Munroe of XKCD fame has answered what’s basically the same question: what-if.xkcd.com/87
$endgroup$
– Mike Scott
Jan 15 at 10:45
2
$begingroup$
The closest you are going to get is the microwave area denial system, which has low risk of deep tissue injury instead burning only the skin. Most people flee before they are injured. en.wikipedia.org/wiki/Active_Denial_System
$endgroup$
– John
Jan 15 at 14:27
3
$begingroup$
Keep a lid on and make sure there is enough steam, this should make sure you steam them instead of grilling them... oh wait, this is wb not cooking....
$endgroup$
– rackandboneman
Jan 15 at 16:52
|
show 10 more comments
15
$begingroup$
Naw, fam. I'm not sure what the math looks like (someone will draft that and put it into an answer, I'm sure), but that would definitely kill the person you are trying to repel.
$endgroup$
– user49466
Jan 15 at 4:14
7
$begingroup$
I have a different idea which might be useful to you. The light is just a distraction, a laser pointer of sorts which shows that defenses are working. Strong enough to blind unwary person and hiding the true defenses: giant fans blowing air in constant stream and doing pressure that way.
$endgroup$
– jo1storm
Jan 15 at 9:53
6
$begingroup$
Randall Munroe of XKCD fame has answered what’s basically the same question: what-if.xkcd.com/87
$endgroup$
– Mike Scott
Jan 15 at 10:45
2
$begingroup$
The closest you are going to get is the microwave area denial system, which has low risk of deep tissue injury instead burning only the skin. Most people flee before they are injured. en.wikipedia.org/wiki/Active_Denial_System
$endgroup$
– John
Jan 15 at 14:27
3
$begingroup$
Keep a lid on and make sure there is enough steam, this should make sure you steam them instead of grilling them... oh wait, this is wb not cooking....
$endgroup$
– rackandboneman
Jan 15 at 16:52
15
15
$begingroup$
Naw, fam. I'm not sure what the math looks like (someone will draft that and put it into an answer, I'm sure), but that would definitely kill the person you are trying to repel.
$endgroup$
– user49466
Jan 15 at 4:14
$begingroup$
Naw, fam. I'm not sure what the math looks like (someone will draft that and put it into an answer, I'm sure), but that would definitely kill the person you are trying to repel.
$endgroup$
– user49466
Jan 15 at 4:14
7
7
$begingroup$
I have a different idea which might be useful to you. The light is just a distraction, a laser pointer of sorts which shows that defenses are working. Strong enough to blind unwary person and hiding the true defenses: giant fans blowing air in constant stream and doing pressure that way.
$endgroup$
– jo1storm
Jan 15 at 9:53
$begingroup$
I have a different idea which might be useful to you. The light is just a distraction, a laser pointer of sorts which shows that defenses are working. Strong enough to blind unwary person and hiding the true defenses: giant fans blowing air in constant stream and doing pressure that way.
$endgroup$
– jo1storm
Jan 15 at 9:53
6
6
$begingroup$
Randall Munroe of XKCD fame has answered what’s basically the same question: what-if.xkcd.com/87
$endgroup$
– Mike Scott
Jan 15 at 10:45
$begingroup$
Randall Munroe of XKCD fame has answered what’s basically the same question: what-if.xkcd.com/87
$endgroup$
– Mike Scott
Jan 15 at 10:45
2
2
$begingroup$
The closest you are going to get is the microwave area denial system, which has low risk of deep tissue injury instead burning only the skin. Most people flee before they are injured. en.wikipedia.org/wiki/Active_Denial_System
$endgroup$
– John
Jan 15 at 14:27
$begingroup$
The closest you are going to get is the microwave area denial system, which has low risk of deep tissue injury instead burning only the skin. Most people flee before they are injured. en.wikipedia.org/wiki/Active_Denial_System
$endgroup$
– John
Jan 15 at 14:27
3
3
$begingroup$
Keep a lid on and make sure there is enough steam, this should make sure you steam them instead of grilling them... oh wait, this is wb not cooking....
$endgroup$
– rackandboneman
Jan 15 at 16:52
$begingroup$
Keep a lid on and make sure there is enough steam, this should make sure you steam them instead of grilling them... oh wait, this is wb not cooking....
$endgroup$
– rackandboneman
Jan 15 at 16:52
|
show 10 more comments
5 Answers
5
active
oldest
votes
$begingroup$
No, it won't be realistic.
The radiation pressure produced by an electromagnetic radiation of intensity, or better irradiance, $I_f$ impinging at an angle $alpha$ on a surface can be calculated according to
$P_Inc = fracI_fc cdot left(cos alpharight)^2$
where c is the speed of light.
You immediately see that, due to the c factor, you need huge irradiance to get meaningful pressures at human scale. Let's say you want to achieve $1 fracNm^2$, you would need an irradiance of about $3 cdot 10^8 fracWm^2$. That would char any human on which it impinges.
In case of a person wearing a perfect reflecting suit,
if the wave is specularly reflected, then the recoil due to the reflected wave will further contribute to the radiation pressure. In the case of a perfect reflector, this pressure will be identical to the pressure caused by the incident wave
$P_Inc= 2 fracI_fc$
It just halves the required radiance to achieve the same pressure, thus still leaving an extremely high value.
edited Jan 15 at 8:58
Community♦
1
answered Jan 15 at 4:13
L.Dutch♦L.Dutch
82.3k27197406
$endgroup$
3
$begingroup$
Unless, of course, that human is very, very shiny. ;-)
$endgroup$
– Joe Bloggs
Jan 15 at 7:43
1
$begingroup$
@JoeBloggs 1nationstyle.files.wordpress.com/2012/10/20121008-142556.jpg
$endgroup$
– Fabian Röling
Jan 15 at 7:45
3
$begingroup$
@L.Dutch: The very shiny comment was referring to the human charring/not charring, not the energy density required. I’m right with you on the daft numbers required.
$endgroup$
– Joe Bloggs
Jan 15 at 8:50
1
$begingroup$
@Renan just to put it into further perspective: 1 N/m^2 is equivalent to around 2 m/s wind speed. In order to get to storm like levels of pressure(20 m/s) we would need around 120 N/m^2. We're definitely vapour before light stops us.
$endgroup$
– Christoph
Jan 15 at 12:34
15
$begingroup$
You might want to clarify: The human in the perfectly reflecting suit won't get hot. The human in the 99.9999% reflecting suit will char.
$endgroup$
– Yakk
Jan 15 at 14:15
|
show 2 more comments
$begingroup$
Not with light pressure. You need 300 megawatts of radiation flux for each Newton of force on the object (equivalent to the force exerted by a ~100 gram weight).
However, you can use microwaves as non-lethal deterrent. A moderate microwave flux is extremely painful on skin, well before it becomes damaging. This is the basis of several experimental crowd control weapons in real life, such as https://en.wikipedia.org/wiki/Active_Denial_System
answered Jan 15 at 5:26
tylisirntylisirn
42923
$endgroup$
1
$begingroup$
You could combine this with visible light such that subjects would believe the visible light was the problem. There is a protection "Reflective materials such as aluminum cooking foil should reflect this radiation and could be used to make clothing that would be protective against this radiation." (from the same source). Also a knight in shining armour would be protected.
$endgroup$
– chasly from UK
Jan 15 at 9:06
$begingroup$
@chaslyfromUK luckily, we haven't used steel armor in well over a hundred years, I believe - and Kevlar and ceramics let microwaves just fine.
$endgroup$
– John Dvorak
Jan 15 at 17:10
add a comment |
$begingroup$
No
It's true that light exerts a pressure, but photons have no rest mass and very little else (thanks AlexP). You're dealing with pressure created by a distribution of energy, which is miniscule.
If you think about it, your skin burns on a beach — but you don't feel even the slightest pressure from the light that's burning you.
Now increase the light such that you could feel the pressure. You'd flash into a fine ash before you could comprehend that you were feeling pressure.
But!
What if you change your goal just a bit? What if the original intent of the light was to flash-burn anyone trying to get down the hall? Your protagonish knows this and dresses accordingly in attire that protects he/she from the burning properties of the light. And yet, as he/she walks down the hall, feels the pressure! pressure that's great enough to hinder progress! That would be a cool twist to the story.
answered Jan 15 at 5:25
JBHJBH
43.4k694207
$endgroup$
4
$begingroup$
Photons have no rest mass. Photons most definitely do have mass, namely $frac hnuc^2$.
$endgroup$
– AlexP
Jan 15 at 9:01
$begingroup$
I really like this answer in that it potentially adds another plot hook in getting said armor - which in turn can be used to reveal or explore some other important aspect of the protagonist or the world.
$endgroup$
– MrSpudtastic
Jan 15 at 14:47
1
$begingroup$
If the armor is ablative, the force doesn't need to come only from the light pressure, but also reaction from the material being ablated.
$endgroup$
– azurefrog
Jan 15 at 21:34
1
$begingroup$
@azurefrog, that's true, but it's not the point. I was trying to create a means of using the OP's idea. Injecting another force or pressure other than the light is counter to the OP's expectations.
$endgroup$
– JBH
Jan 15 at 21:37
add a comment |
$begingroup$
Literally , no. Other answers have dealt with this.
However, if you allow that the possible intruders will not be armored, you can do something like it.
Produce the light by an array of high-powered emitters. Each separate emitter produces a beam which focusses down to a very, very small spot about 1/4 to 1/10th the length of the hallway. The beams are all aimed at different spots within the hallway, and none of them is aimed directly down the corridor. As a result, virtually all of the emitted light will be absorbed by the walls.
The result will be hazardous to look at from the end of the hall, due to unavoidable (hopefully small) reflections. However, if you attempt to traverse the hall, you'll eventually encounter a wall of "hot spots", where the power density is so great as to burn holes in you. Before you get to that point, the perceived temperature will rise to unbearable levels, and this should keep intruders out.
Of course, this won't work in the presence of suitable armor - if the intruder simply rushes the corridor, she will pass almost instantly through the "death zone", and ought to be able to make it.
answered Jan 15 at 14:17
WhatRoughBeastWhatRoughBeast
22.3k23178
$endgroup$
add a comment |
$begingroup$
Maybe not visible light, but possibly an electrostatic wall
answered Jan 15 at 22:22
jreesejreese
411
$endgroup$
add a comment |
Your Answer
StackExchange.ifUsing("editor", function ()
return StackExchange.using("mathjaxEditing", function ()
StackExchange.MarkdownEditor.creationCallbacks.add(function (editor, postfix)
StackExchange.mathjaxEditing.prepareWmdForMathJax(editor, postfix, [["$", "$"], ["\\(","\\)"]]);
);
);
, "mathjax-editing");
StackExchange.ready(function()
var channelOptions =
tags: "".split(" "),
id: "579"
;
initTagRenderer("".split(" "), "".split(" "), channelOptions);
StackExchange.using("externalEditor", function()
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled)
StackExchange.using("snippets", function()
createEditor();
);
else
createEditor();
);
function createEditor()
StackExchange.prepareEditor(
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: false,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: null,
bindNavPrevention: true,
postfix: "",
imageUploader:
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
,
noCode: true, onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
);
);
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function ()
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fworldbuilding.stackexchange.com%2fquestions%2f136612%2fusing-light-as-a-barrier-to-block-people-without-grilling-them%23new-answer', 'question_page');
);
Post as a guest
Required, but never shown
5 Answers
5
active
oldest
votes
5 Answers
5
active
oldest
votes
active
oldest
votes
active
oldest
votes
$begingroup$
No, it won't be realistic.
The radiation pressure produced by an electromagnetic radiation of intensity, or better irradiance, $I_f$ impinging at an angle $alpha$ on a surface can be calculated according to
$P_Inc = fracI_fc cdot left(cos alpharight)^2$
where c is the speed of light.
You immediately see that, due to the c factor, you need huge irradiance to get meaningful pressures at human scale. Let's say you want to achieve $1 fracNm^2$, you would need an irradiance of about $3 cdot 10^8 fracWm^2$. That would char any human on which it impinges.
In case of a person wearing a perfect reflecting suit,
if the wave is specularly reflected, then the recoil due to the reflected wave will further contribute to the radiation pressure. In the case of a perfect reflector, this pressure will be identical to the pressure caused by the incident wave
$P_Inc= 2 fracI_fc$
It just halves the required radiance to achieve the same pressure, thus still leaving an extremely high value.
edited Jan 15 at 8:58
Community♦
1
answered Jan 15 at 4:13
L.Dutch♦L.Dutch
82.3k27197406
$endgroup$
3
$begingroup$
Unless, of course, that human is very, very shiny. ;-)
$endgroup$
– Joe Bloggs
Jan 15 at 7:43
1
$begingroup$
@JoeBloggs 1nationstyle.files.wordpress.com/2012/10/20121008-142556.jpg
$endgroup$
– Fabian Röling
Jan 15 at 7:45
3
$begingroup$
@L.Dutch: The very shiny comment was referring to the human charring/not charring, not the energy density required. I’m right with you on the daft numbers required.
$endgroup$
– Joe Bloggs
Jan 15 at 8:50
1
$begingroup$
@Renan just to put it into further perspective: 1 N/m^2 is equivalent to around 2 m/s wind speed. In order to get to storm like levels of pressure(20 m/s) we would need around 120 N/m^2. We're definitely vapour before light stops us.
$endgroup$
– Christoph
Jan 15 at 12:34
15
$begingroup$
You might want to clarify: The human in the perfectly reflecting suit won't get hot. The human in the 99.9999% reflecting suit will char.
$endgroup$
– Yakk
Jan 15 at 14:15
|
show 2 more comments
$begingroup$
No, it won't be realistic.
The radiation pressure produced by an electromagnetic radiation of intensity, or better irradiance, $I_f$ impinging at an angle $alpha$ on a surface can be calculated according to
$P_Inc = fracI_fc cdot left(cos alpharight)^2$
where c is the speed of light.
You immediately see that, due to the c factor, you need huge irradiance to get meaningful pressures at human scale. Let's say you want to achieve $1 fracNm^2$, you would need an irradiance of about $3 cdot 10^8 fracWm^2$. That would char any human on which it impinges.
In case of a person wearing a perfect reflecting suit,
if the wave is specularly reflected, then the recoil due to the reflected wave will further contribute to the radiation pressure. In the case of a perfect reflector, this pressure will be identical to the pressure caused by the incident wave
$P_Inc= 2 fracI_fc$
It just halves the required radiance to achieve the same pressure, thus still leaving an extremely high value.
edited Jan 15 at 8:58
Community♦
1
answered Jan 15 at 4:13
L.Dutch♦L.Dutch
82.3k27197406
$endgroup$
3
$begingroup$
Unless, of course, that human is very, very shiny. ;-)
$endgroup$
– Joe Bloggs
Jan 15 at 7:43
1
$begingroup$
@JoeBloggs 1nationstyle.files.wordpress.com/2012/10/20121008-142556.jpg
$endgroup$
– Fabian Röling
Jan 15 at 7:45
3
$begingroup$
@L.Dutch: The very shiny comment was referring to the human charring/not charring, not the energy density required. I’m right with you on the daft numbers required.
$endgroup$
– Joe Bloggs
Jan 15 at 8:50
1
$begingroup$
@Renan just to put it into further perspective: 1 N/m^2 is equivalent to around 2 m/s wind speed. In order to get to storm like levels of pressure(20 m/s) we would need around 120 N/m^2. We're definitely vapour before light stops us.
$endgroup$
– Christoph
Jan 15 at 12:34
15
$begingroup$
You might want to clarify: The human in the perfectly reflecting suit won't get hot. The human in the 99.9999% reflecting suit will char.
$endgroup$
– Yakk
Jan 15 at 14:15
|
show 2 more comments
$begingroup$
No, it won't be realistic.
The radiation pressure produced by an electromagnetic radiation of intensity, or better irradiance, $I_f$ impinging at an angle $alpha$ on a surface can be calculated according to
$P_Inc = fracI_fc cdot left(cos alpharight)^2$
where c is the speed of light.
You immediately see that, due to the c factor, you need huge irradiance to get meaningful pressures at human scale. Let's say you want to achieve $1 fracNm^2$, you would need an irradiance of about $3 cdot 10^8 fracWm^2$. That would char any human on which it impinges.
In case of a person wearing a perfect reflecting suit,
if the wave is specularly reflected, then the recoil due to the reflected wave will further contribute to the radiation pressure. In the case of a perfect reflector, this pressure will be identical to the pressure caused by the incident wave
$P_Inc= 2 fracI_fc$
It just halves the required radiance to achieve the same pressure, thus still leaving an extremely high value.
edited Jan 15 at 8:58
Community♦
1
answered Jan 15 at 4:13
L.Dutch♦L.Dutch
82.3k27197406
$endgroup$
No, it won't be realistic.
The radiation pressure produced by an electromagnetic radiation of intensity, or better irradiance, $I_f$ impinging at an angle $alpha$ on a surface can be calculated according to
$P_Inc = fracI_fc cdot left(cos alpharight)^2$
where c is the speed of light.
You immediately see that, due to the c factor, you need huge irradiance to get meaningful pressures at human scale. Let's say you want to achieve $1 fracNm^2$, you would need an irradiance of about $3 cdot 10^8 fracWm^2$. That would char any human on which it impinges.
In case of a person wearing a perfect reflecting suit,
if the wave is specularly reflected, then the recoil due to the reflected wave will further contribute to the radiation pressure. In the case of a perfect reflector, this pressure will be identical to the pressure caused by the incident wave
$P_Inc= 2 fracI_fc$
It just halves the required radiance to achieve the same pressure, thus still leaving an extremely high value.
edited Jan 15 at 8:58
Community♦
1
answered Jan 15 at 4:13
L.Dutch♦L.Dutch
82.3k27197406
edited Jan 15 at 8:58
Community♦
1
edited Jan 15 at 8:58
Community♦
1
edited Jan 15 at 8:58
Community♦
1
1
answered Jan 15 at 4:13
L.Dutch♦L.Dutch
82.3k27197406
answered Jan 15 at 4:13
L.Dutch♦L.Dutch
82.3k27197406
answered Jan 15 at 4:13
L.Dutch♦L.Dutch
82.3k27197406
82.3k27197406
3
$begingroup$
Unless, of course, that human is very, very shiny. ;-)
$endgroup$
– Joe Bloggs
Jan 15 at 7:43
1
$begingroup$
@JoeBloggs 1nationstyle.files.wordpress.com/2012/10/20121008-142556.jpg
$endgroup$
– Fabian Röling
Jan 15 at 7:45
3
$begingroup$
@L.Dutch: The very shiny comment was referring to the human charring/not charring, not the energy density required. I’m right with you on the daft numbers required.
$endgroup$
– Joe Bloggs
Jan 15 at 8:50
1
$begingroup$
@Renan just to put it into further perspective: 1 N/m^2 is equivalent to around 2 m/s wind speed. In order to get to storm like levels of pressure(20 m/s) we would need around 120 N/m^2. We're definitely vapour before light stops us.
$endgroup$
– Christoph
Jan 15 at 12:34
15
$begingroup$
You might want to clarify: The human in the perfectly reflecting suit won't get hot. The human in the 99.9999% reflecting suit will char.
$endgroup$
– Yakk
Jan 15 at 14:15
|
show 2 more comments
3
$begingroup$
Unless, of course, that human is very, very shiny. ;-)
$endgroup$
– Joe Bloggs
Jan 15 at 7:43
1
$begingroup$
@JoeBloggs 1nationstyle.files.wordpress.com/2012/10/20121008-142556.jpg
$endgroup$
– Fabian Röling
Jan 15 at 7:45
3
$begingroup$
@L.Dutch: The very shiny comment was referring to the human charring/not charring, not the energy density required. I’m right with you on the daft numbers required.
$endgroup$
– Joe Bloggs
Jan 15 at 8:50
1
$begingroup$
@Renan just to put it into further perspective: 1 N/m^2 is equivalent to around 2 m/s wind speed. In order to get to storm like levels of pressure(20 m/s) we would need around 120 N/m^2. We're definitely vapour before light stops us.
$endgroup$
– Christoph
Jan 15 at 12:34
15
$begingroup$
You might want to clarify: The human in the perfectly reflecting suit won't get hot. The human in the 99.9999% reflecting suit will char.
$endgroup$
– Yakk
Jan 15 at 14:15
3
3
$begingroup$
Unless, of course, that human is very, very shiny. ;-)
$endgroup$
– Joe Bloggs
Jan 15 at 7:43
$begingroup$
Unless, of course, that human is very, very shiny. ;-)
$endgroup$
– Joe Bloggs
Jan 15 at 7:43
1
1
$begingroup$
@JoeBloggs 1nationstyle.files.wordpress.com/2012/10/20121008-142556.jpg
$endgroup$
– Fabian Röling
Jan 15 at 7:45
$begingroup$
@JoeBloggs 1nationstyle.files.wordpress.com/2012/10/20121008-142556.jpg
$endgroup$
– Fabian Röling
Jan 15 at 7:45
3
3
$begingroup$
@L.Dutch: The very shiny comment was referring to the human charring/not charring, not the energy density required. I’m right with you on the daft numbers required.
$endgroup$
– Joe Bloggs
Jan 15 at 8:50
$begingroup$
@L.Dutch: The very shiny comment was referring to the human charring/not charring, not the energy density required. I’m right with you on the daft numbers required.
$endgroup$
– Joe Bloggs
Jan 15 at 8:50
1
1
$begingroup$
@Renan just to put it into further perspective: 1 N/m^2 is equivalent to around 2 m/s wind speed. In order to get to storm like levels of pressure(20 m/s) we would need around 120 N/m^2. We're definitely vapour before light stops us.
$endgroup$
– Christoph
Jan 15 at 12:34
$begingroup$
@Renan just to put it into further perspective: 1 N/m^2 is equivalent to around 2 m/s wind speed. In order to get to storm like levels of pressure(20 m/s) we would need around 120 N/m^2. We're definitely vapour before light stops us.
$endgroup$
– Christoph
Jan 15 at 12:34
15
15
$begingroup$
You might want to clarify: The human in the perfectly reflecting suit won't get hot. The human in the 99.9999% reflecting suit will char.
$endgroup$
– Yakk
Jan 15 at 14:15
$begingroup$
You might want to clarify: The human in the perfectly reflecting suit won't get hot. The human in the 99.9999% reflecting suit will char.
$endgroup$
– Yakk
Jan 15 at 14:15
|
show 2 more comments
$begingroup$
Not with light pressure. You need 300 megawatts of radiation flux for each Newton of force on the object (equivalent to the force exerted by a ~100 gram weight).
However, you can use microwaves as non-lethal deterrent. A moderate microwave flux is extremely painful on skin, well before it becomes damaging. This is the basis of several experimental crowd control weapons in real life, such as https://en.wikipedia.org/wiki/Active_Denial_System
answered Jan 15 at 5:26
tylisirntylisirn
42923
$endgroup$
1
$begingroup$
You could combine this with visible light such that subjects would believe the visible light was the problem. There is a protection "Reflective materials such as aluminum cooking foil should reflect this radiation and could be used to make clothing that would be protective against this radiation." (from the same source). Also a knight in shining armour would be protected.
$endgroup$
– chasly from UK
Jan 15 at 9:06
$begingroup$
@chaslyfromUK luckily, we haven't used steel armor in well over a hundred years, I believe - and Kevlar and ceramics let microwaves just fine.
$endgroup$
– John Dvorak
Jan 15 at 17:10
add a comment |
$begingroup$
Not with light pressure. You need 300 megawatts of radiation flux for each Newton of force on the object (equivalent to the force exerted by a ~100 gram weight).
However, you can use microwaves as non-lethal deterrent. A moderate microwave flux is extremely painful on skin, well before it becomes damaging. This is the basis of several experimental crowd control weapons in real life, such as https://en.wikipedia.org/wiki/Active_Denial_System
answered Jan 15 at 5:26
tylisirntylisirn
42923
$endgroup$
1
$begingroup$
You could combine this with visible light such that subjects would believe the visible light was the problem. There is a protection "Reflective materials such as aluminum cooking foil should reflect this radiation and could be used to make clothing that would be protective against this radiation." (from the same source). Also a knight in shining armour would be protected.
$endgroup$
– chasly from UK
Jan 15 at 9:06
$begingroup$
@chaslyfromUK luckily, we haven't used steel armor in well over a hundred years, I believe - and Kevlar and ceramics let microwaves just fine.
$endgroup$
– John Dvorak
Jan 15 at 17:10
add a comment |
$begingroup$
Not with light pressure. You need 300 megawatts of radiation flux for each Newton of force on the object (equivalent to the force exerted by a ~100 gram weight).
However, you can use microwaves as non-lethal deterrent. A moderate microwave flux is extremely painful on skin, well before it becomes damaging. This is the basis of several experimental crowd control weapons in real life, such as https://en.wikipedia.org/wiki/Active_Denial_System
answered Jan 15 at 5:26
tylisirntylisirn
42923
$endgroup$
Not with light pressure. You need 300 megawatts of radiation flux for each Newton of force on the object (equivalent to the force exerted by a ~100 gram weight).
However, you can use microwaves as non-lethal deterrent. A moderate microwave flux is extremely painful on skin, well before it becomes damaging. This is the basis of several experimental crowd control weapons in real life, such as https://en.wikipedia.org/wiki/Active_Denial_System
answered Jan 15 at 5:26
tylisirntylisirn
42923
answered Jan 15 at 5:26
tylisirntylisirn
42923
answered Jan 15 at 5:26
tylisirntylisirn
42923
answered Jan 15 at 5:26
tylisirntylisirn
42923
42923
1
$begingroup$
You could combine this with visible light such that subjects would believe the visible light was the problem. There is a protection "Reflective materials such as aluminum cooking foil should reflect this radiation and could be used to make clothing that would be protective against this radiation." (from the same source). Also a knight in shining armour would be protected.
$endgroup$
– chasly from UK
Jan 15 at 9:06
$begingroup$
@chaslyfromUK luckily, we haven't used steel armor in well over a hundred years, I believe - and Kevlar and ceramics let microwaves just fine.
$endgroup$
– John Dvorak
Jan 15 at 17:10
add a comment |
1
$begingroup$
You could combine this with visible light such that subjects would believe the visible light was the problem. There is a protection "Reflective materials such as aluminum cooking foil should reflect this radiation and could be used to make clothing that would be protective against this radiation." (from the same source). Also a knight in shining armour would be protected.
$endgroup$
– chasly from UK
Jan 15 at 9:06
$begingroup$
@chaslyfromUK luckily, we haven't used steel armor in well over a hundred years, I believe - and Kevlar and ceramics let microwaves just fine.
$endgroup$
– John Dvorak
Jan 15 at 17:10
1
1
$begingroup$
You could combine this with visible light such that subjects would believe the visible light was the problem. There is a protection "Reflective materials such as aluminum cooking foil should reflect this radiation and could be used to make clothing that would be protective against this radiation." (from the same source). Also a knight in shining armour would be protected.
$endgroup$
– chasly from UK
Jan 15 at 9:06
$begingroup$
You could combine this with visible light such that subjects would believe the visible light was the problem. There is a protection "Reflective materials such as aluminum cooking foil should reflect this radiation and could be used to make clothing that would be protective against this radiation." (from the same source). Also a knight in shining armour would be protected.
$endgroup$
– chasly from UK
Jan 15 at 9:06
$begingroup$
@chaslyfromUK luckily, we haven't used steel armor in well over a hundred years, I believe - and Kevlar and ceramics let microwaves just fine.
$endgroup$
– John Dvorak
Jan 15 at 17:10
$begingroup$
@chaslyfromUK luckily, we haven't used steel armor in well over a hundred years, I believe - and Kevlar and ceramics let microwaves just fine.
$endgroup$
– John Dvorak
Jan 15 at 17:10
add a comment |
$begingroup$
No
It's true that light exerts a pressure, but photons have no rest mass and very little else (thanks AlexP). You're dealing with pressure created by a distribution of energy, which is miniscule.
If you think about it, your skin burns on a beach — but you don't feel even the slightest pressure from the light that's burning you.
Now increase the light such that you could feel the pressure. You'd flash into a fine ash before you could comprehend that you were feeling pressure.
But!
What if you change your goal just a bit? What if the original intent of the light was to flash-burn anyone trying to get down the hall? Your protagonish knows this and dresses accordingly in attire that protects he/she from the burning properties of the light. And yet, as he/she walks down the hall, feels the pressure! pressure that's great enough to hinder progress! That would be a cool twist to the story.
answered Jan 15 at 5:25
JBHJBH
43.4k694207
$endgroup$
4
$begingroup$
Photons have no rest mass. Photons most definitely do have mass, namely $frac hnuc^2$.
$endgroup$
– AlexP
Jan 15 at 9:01
$begingroup$
I really like this answer in that it potentially adds another plot hook in getting said armor - which in turn can be used to reveal or explore some other important aspect of the protagonist or the world.
$endgroup$
– MrSpudtastic
Jan 15 at 14:47
1
$begingroup$
If the armor is ablative, the force doesn't need to come only from the light pressure, but also reaction from the material being ablated.
$endgroup$
– azurefrog
Jan 15 at 21:34
1
$begingroup$
@azurefrog, that's true, but it's not the point. I was trying to create a means of using the OP's idea. Injecting another force or pressure other than the light is counter to the OP's expectations.
$endgroup$
– JBH
Jan 15 at 21:37
add a comment |
$begingroup$
No
It's true that light exerts a pressure, but photons have no rest mass and very little else (thanks AlexP). You're dealing with pressure created by a distribution of energy, which is miniscule.
If you think about it, your skin burns on a beach — but you don't feel even the slightest pressure from the light that's burning you.
Now increase the light such that you could feel the pressure. You'd flash into a fine ash before you could comprehend that you were feeling pressure.
But!
What if you change your goal just a bit? What if the original intent of the light was to flash-burn anyone trying to get down the hall? Your protagonish knows this and dresses accordingly in attire that protects he/she from the burning properties of the light. And yet, as he/she walks down the hall, feels the pressure! pressure that's great enough to hinder progress! That would be a cool twist to the story.
answered Jan 15 at 5:25
JBHJBH
43.4k694207
$endgroup$
4
$begingroup$
Photons have no rest mass. Photons most definitely do have mass, namely $frac hnuc^2$.
$endgroup$
– AlexP
Jan 15 at 9:01
$begingroup$
I really like this answer in that it potentially adds another plot hook in getting said armor - which in turn can be used to reveal or explore some other important aspect of the protagonist or the world.
$endgroup$
– MrSpudtastic
Jan 15 at 14:47
1
$begingroup$
If the armor is ablative, the force doesn't need to come only from the light pressure, but also reaction from the material being ablated.
$endgroup$
– azurefrog
Jan 15 at 21:34
1
$begingroup$
@azurefrog, that's true, but it's not the point. I was trying to create a means of using the OP's idea. Injecting another force or pressure other than the light is counter to the OP's expectations.
$endgroup$
– JBH
Jan 15 at 21:37
add a comment |
$begingroup$
No
It's true that light exerts a pressure, but photons have no rest mass and very little else (thanks AlexP). You're dealing with pressure created by a distribution of energy, which is miniscule.
If you think about it, your skin burns on a beach — but you don't feel even the slightest pressure from the light that's burning you.
Now increase the light such that you could feel the pressure. You'd flash into a fine ash before you could comprehend that you were feeling pressure.
But!
What if you change your goal just a bit? What if the original intent of the light was to flash-burn anyone trying to get down the hall? Your protagonish knows this and dresses accordingly in attire that protects he/she from the burning properties of the light. And yet, as he/she walks down the hall, feels the pressure! pressure that's great enough to hinder progress! That would be a cool twist to the story.
answered Jan 15 at 5:25
JBHJBH
43.4k694207
$endgroup$
No
It's true that light exerts a pressure, but photons have no rest mass and very little else (thanks AlexP). You're dealing with pressure created by a distribution of energy, which is miniscule.
If you think about it, your skin burns on a beach — but you don't feel even the slightest pressure from the light that's burning you.
Now increase the light such that you could feel the pressure. You'd flash into a fine ash before you could comprehend that you were feeling pressure.
But!
What if you change your goal just a bit? What if the original intent of the light was to flash-burn anyone trying to get down the hall? Your protagonish knows this and dresses accordingly in attire that protects he/she from the burning properties of the light. And yet, as he/she walks down the hall, feels the pressure! pressure that's great enough to hinder progress! That would be a cool twist to the story.
answered Jan 15 at 5:25
JBHJBH
43.4k694207
edited Jan 15 at 16:28
answered Jan 15 at 5:25
JBHJBH
43.4k694207
answered Jan 15 at 5:25
JBHJBH
43.4k694207
answered Jan 15 at 5:25
JBHJBH
43.4k694207
43.4k694207
4
$begingroup$
Photons have no rest mass. Photons most definitely do have mass, namely $frac hnuc^2$.
$endgroup$
– AlexP
Jan 15 at 9:01
$begingroup$
I really like this answer in that it potentially adds another plot hook in getting said armor - which in turn can be used to reveal or explore some other important aspect of the protagonist or the world.
$endgroup$
– MrSpudtastic
Jan 15 at 14:47
1
$begingroup$
If the armor is ablative, the force doesn't need to come only from the light pressure, but also reaction from the material being ablated.
$endgroup$
– azurefrog
Jan 15 at 21:34
1
$begingroup$
@azurefrog, that's true, but it's not the point. I was trying to create a means of using the OP's idea. Injecting another force or pressure other than the light is counter to the OP's expectations.
$endgroup$
– JBH
Jan 15 at 21:37
add a comment |
4
$begingroup$
Photons have no rest mass. Photons most definitely do have mass, namely $frac hnuc^2$.
$endgroup$
– AlexP
Jan 15 at 9:01
$begingroup$
I really like this answer in that it potentially adds another plot hook in getting said armor - which in turn can be used to reveal or explore some other important aspect of the protagonist or the world.
$endgroup$
– MrSpudtastic
Jan 15 at 14:47
1
$begingroup$
If the armor is ablative, the force doesn't need to come only from the light pressure, but also reaction from the material being ablated.
$endgroup$
– azurefrog
Jan 15 at 21:34
1
$begingroup$
@azurefrog, that's true, but it's not the point. I was trying to create a means of using the OP's idea. Injecting another force or pressure other than the light is counter to the OP's expectations.
$endgroup$
– JBH
Jan 15 at 21:37
4
4
$begingroup$
Photons have no rest mass. Photons most definitely do have mass, namely $frac hnuc^2$.
$endgroup$
– AlexP
Jan 15 at 9:01
$begingroup$
Photons have no rest mass. Photons most definitely do have mass, namely $frac hnuc^2$.
$endgroup$
– AlexP
Jan 15 at 9:01
$begingroup$
I really like this answer in that it potentially adds another plot hook in getting said armor - which in turn can be used to reveal or explore some other important aspect of the protagonist or the world.
$endgroup$
– MrSpudtastic
Jan 15 at 14:47
$begingroup$
I really like this answer in that it potentially adds another plot hook in getting said armor - which in turn can be used to reveal or explore some other important aspect of the protagonist or the world.
$endgroup$
– MrSpudtastic
Jan 15 at 14:47
1
1
$begingroup$
If the armor is ablative, the force doesn't need to come only from the light pressure, but also reaction from the material being ablated.
$endgroup$
– azurefrog
Jan 15 at 21:34
$begingroup$
If the armor is ablative, the force doesn't need to come only from the light pressure, but also reaction from the material being ablated.
$endgroup$
– azurefrog
Jan 15 at 21:34
1
1
$begingroup$
@azurefrog, that's true, but it's not the point. I was trying to create a means of using the OP's idea. Injecting another force or pressure other than the light is counter to the OP's expectations.
$endgroup$
– JBH
Jan 15 at 21:37
$begingroup$
@azurefrog, that's true, but it's not the point. I was trying to create a means of using the OP's idea. Injecting another force or pressure other than the light is counter to the OP's expectations.
$endgroup$
– JBH
Jan 15 at 21:37
add a comment |
$begingroup$
Literally , no. Other answers have dealt with this.
However, if you allow that the possible intruders will not be armored, you can do something like it.
Produce the light by an array of high-powered emitters. Each separate emitter produces a beam which focusses down to a very, very small spot about 1/4 to 1/10th the length of the hallway. The beams are all aimed at different spots within the hallway, and none of them is aimed directly down the corridor. As a result, virtually all of the emitted light will be absorbed by the walls.
The result will be hazardous to look at from the end of the hall, due to unavoidable (hopefully small) reflections. However, if you attempt to traverse the hall, you'll eventually encounter a wall of "hot spots", where the power density is so great as to burn holes in you. Before you get to that point, the perceived temperature will rise to unbearable levels, and this should keep intruders out.
Of course, this won't work in the presence of suitable armor - if the intruder simply rushes the corridor, she will pass almost instantly through the "death zone", and ought to be able to make it.
answered Jan 15 at 14:17
WhatRoughBeastWhatRoughBeast
22.3k23178
$endgroup$
add a comment |
$begingroup$
Literally , no. Other answers have dealt with this.
However, if you allow that the possible intruders will not be armored, you can do something like it.
Produce the light by an array of high-powered emitters. Each separate emitter produces a beam which focusses down to a very, very small spot about 1/4 to 1/10th the length of the hallway. The beams are all aimed at different spots within the hallway, and none of them is aimed directly down the corridor. As a result, virtually all of the emitted light will be absorbed by the walls.
The result will be hazardous to look at from the end of the hall, due to unavoidable (hopefully small) reflections. However, if you attempt to traverse the hall, you'll eventually encounter a wall of "hot spots", where the power density is so great as to burn holes in you. Before you get to that point, the perceived temperature will rise to unbearable levels, and this should keep intruders out.
Of course, this won't work in the presence of suitable armor - if the intruder simply rushes the corridor, she will pass almost instantly through the "death zone", and ought to be able to make it.
answered Jan 15 at 14:17
WhatRoughBeastWhatRoughBeast
22.3k23178
$endgroup$
add a comment |
$begingroup$
Literally , no. Other answers have dealt with this.
However, if you allow that the possible intruders will not be armored, you can do something like it.
Produce the light by an array of high-powered emitters. Each separate emitter produces a beam which focusses down to a very, very small spot about 1/4 to 1/10th the length of the hallway. The beams are all aimed at different spots within the hallway, and none of them is aimed directly down the corridor. As a result, virtually all of the emitted light will be absorbed by the walls.
The result will be hazardous to look at from the end of the hall, due to unavoidable (hopefully small) reflections. However, if you attempt to traverse the hall, you'll eventually encounter a wall of "hot spots", where the power density is so great as to burn holes in you. Before you get to that point, the perceived temperature will rise to unbearable levels, and this should keep intruders out.
Of course, this won't work in the presence of suitable armor - if the intruder simply rushes the corridor, she will pass almost instantly through the "death zone", and ought to be able to make it.
answered Jan 15 at 14:17
WhatRoughBeastWhatRoughBeast
22.3k23178
$endgroup$
Literally , no. Other answers have dealt with this.
However, if you allow that the possible intruders will not be armored, you can do something like it.
Produce the light by an array of high-powered emitters. Each separate emitter produces a beam which focusses down to a very, very small spot about 1/4 to 1/10th the length of the hallway. The beams are all aimed at different spots within the hallway, and none of them is aimed directly down the corridor. As a result, virtually all of the emitted light will be absorbed by the walls.
The result will be hazardous to look at from the end of the hall, due to unavoidable (hopefully small) reflections. However, if you attempt to traverse the hall, you'll eventually encounter a wall of "hot spots", where the power density is so great as to burn holes in you. Before you get to that point, the perceived temperature will rise to unbearable levels, and this should keep intruders out.
Of course, this won't work in the presence of suitable armor - if the intruder simply rushes the corridor, she will pass almost instantly through the "death zone", and ought to be able to make it.
answered Jan 15 at 14:17
WhatRoughBeastWhatRoughBeast
22.3k23178
answered Jan 15 at 14:17
WhatRoughBeastWhatRoughBeast
22.3k23178
answered Jan 15 at 14:17
WhatRoughBeastWhatRoughBeast
22.3k23178
answered Jan 15 at 14:17
WhatRoughBeastWhatRoughBeast
22.3k23178
22.3k23178
add a comment |
add a comment |
$begingroup$
Maybe not visible light, but possibly an electrostatic wall
answered Jan 15 at 22:22
jreesejreese
411
$endgroup$
add a comment |
$begingroup$
Maybe not visible light, but possibly an electrostatic wall
answered Jan 15 at 22:22
jreesejreese
411
$endgroup$
add a comment |
$begingroup$
Maybe not visible light, but possibly an electrostatic wall
answered Jan 15 at 22:22
jreesejreese
411
$endgroup$
Maybe not visible light, but possibly an electrostatic wall
answered Jan 15 at 22:22
jreesejreese
411
answered Jan 15 at 22:22
jreesejreese
411
answered Jan 15 at 22:22
jreesejreese
411
answered Jan 15 at 22:22
jreesejreese
411
411
add a comment |
add a comment |
Thanks for contributing an answer to Worldbuilding Stack Exchange!
- Please be sure to answer the question. Provide details and share your research!
But avoid …
- Asking for help, clarification, or responding to other answers.
- Making statements based on opinion; back them up with references or personal experience.
Use MathJax to format equations. MathJax reference.
To learn more, see our tips on writing great answers.
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function ()
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fworldbuilding.stackexchange.com%2fquestions%2f136612%2fusing-light-as-a-barrier-to-block-people-without-grilling-them%23new-answer', 'question_page');
);
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
15
$begingroup$
Naw, fam. I'm not sure what the math looks like (someone will draft that and put it into an answer, I'm sure), but that would definitely kill the person you are trying to repel.
$endgroup$
– user49466
Jan 15 at 4:14
7
$begingroup$
I have a different idea which might be useful to you. The light is just a distraction, a laser pointer of sorts which shows that defenses are working. Strong enough to blind unwary person and hiding the true defenses: giant fans blowing air in constant stream and doing pressure that way.
$endgroup$
– jo1storm
Jan 15 at 9:53
6
$begingroup$
Randall Munroe of XKCD fame has answered what’s basically the same question: what-if.xkcd.com/87
$endgroup$
– Mike Scott
Jan 15 at 10:45
2
$begingroup$
The closest you are going to get is the microwave area denial system, which has low risk of deep tissue injury instead burning only the skin. Most people flee before they are injured. en.wikipedia.org/wiki/Active_Denial_System
$endgroup$
– John
Jan 15 at 14:27
3
$begingroup$
Keep a lid on and make sure there is enough steam, this should make sure you steam them instead of grilling them... oh wait, this is wb not cooking....
$endgroup$
– rackandboneman
Jan 15 at 16:52