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Lasers and Reaction Time -Updated 9/5/12-

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Lasers and Reaction Time -Updated 9/5/12-

Postby Proto-Mind » Sat Jun 30, 2012 12:26 pm

It seems that if there is an opportunity, people will try giving characters nanosecond reaction time. This is done by observing a character either dodging a laser or deflecting it. However, this cannot be easily determined like bullets. In order to determine if a character can dodge lasers, it is important to observe its properties.

Assume that a character deflects a laser beam. All right, so perhaps in that world it is a laser, and perhaps in that world, lasers work different from ours. This does not mean that character has nanosecond RT. Below is a list of determining if a laser is truly a laser in every sense of the word.

1. Is it called "laser" or "laser beam", or is "laser" in the name?
The name of a beam can be misnomer. For this reason, it is important not to accept something as being a laser, just because it is called a laser. In Kingdom Hearts 2, in the battle against Xemnas, the information box at the top left says, "Use Reflect to deflect lasers", yet these do not share the property of a laser. [1] In Metroid II: Return of Samus, Autracks are said to fire lasers, [2] but again they act nothing like lasers. Even Samus' Spazer Beam is called a "Spazer Laser Beam". [3] In Final Fantasy VIII, one of Quistis' Limit Breaks is "Laser Eye", [4] but again, it acts more like a beam, rather than a laser.

2. Can the laser beam be seen?
If a laser can be seen, this does not necessarily mean it isn't a laser. Most lasers are in the infrared (IR) spectrum, which is why it appears invisible to the naked eye. In order to see a laser, it depends on one of three things. The first thing is the environment. If dust, rain, smoke, or mist is present, the laser will become visible. The second thing this depends on is the type of laser. Two types of visible lasers are diode lasers and gas lasers. [5] The third thing depends on whether or not someone is wearing eyewear that allows him or her to see different light spectrums.

So if lasers can be visible, does this mean that we should accept a laser to be a laser if it is any fiction that represents it visibly? Not necessarily. If a laser is visible, it must be proven that it is a diode or gas laser, rather than assuming it is so. It must also work similarly to the way lasers work. Fiction writers/artists will tend to represent lasers visibly because they either are unaware most lasers are invisible, or they're just call it a laser because it's in a SF setting.

3. Does the laser beam make sound?
When you turn on a flashlight, do you hear a noise being produced by the light? Probably not. When lasers are fired in fiction, they tend to give a sound. This isn't necessarily true in the real world. Your Blu-ray doesn't produce a sound when the laser is fired, nor does the checkout at a grocery store. If sound is being produced by a laser, it is because of the thermal expansion of the air. Think of thunder when it's produced by lightning. It will produce a popping sound or a loud humming noise.

Another way lasers can produce sound is when they hit their target. It isn't so much of the laser that is producing the sound, but the object being vaporized. Anything else you hear from a laser is likely not coming from the laser, but from the flash lamp. Anyway, although lasers shouldn't make sound because they're light, it should be expected to come from a laser weapon if it's powerful enough to thermally expand air. This means that if the laser produces a sound in fiction, but it's not a popping sound or loud humming noise, it's probably not a laser.

4. Does the laser beam appear as a straight line instantaneously?
In fiction like the the episode, The Mystery of the Lizard Men in Jonny Quest, [6] or Quistis' Laser Eye, [4] or even in Afro Samurai: Resurrection where Afro battles the Afro Droid, [7] these lasers can be seen traveling. If you can see the laser beam traveling, it's probably not a laser.

5. Does the laser beam appear as bolts or pulses?
While it is possible to make a laser fire in pulses, this isn't the same idea as what the question has in mind. In other words, if fiction presents laser beams as bolts or pulses, such as in Kingdom Hearts 2, [1] or Metroid II: Return of Samus, or in the Kirby series, chances are it's not a laser.

6. Does the laser beam bounce off objects or bend without any explanation?
In the Kirby series, the laser power-up will allow Kirby to fire a laser beam, which can ricochet off of surfaces. [8][9][10] This works nothing like a laser. The only time a laser can ever bounce off a surface or angle in a different position is if the laser is bouncing off a polished object like a mirror, or if it is caught in the event horizon of a black hole or some other kind of extremely high gravity.

7. Does it take time for the laser beam to reflect off a polished surface, such as a mirror?
When light hits something with a reflective property, it takes no time to reflect from the surface. It is instantaneous to the human eye. If, for any reason at all, it takes time for the laser to reflect off an object, it's probably not a laser.

8. Does the laser beam produce a bright light when it hits an object?
Not all lasers produce a bright flash when an object is hit. For example, a laser pointer will not do this because they're not powerful enough. In the case of a laser weapon, chances are it will produce a bright light. If it doesn't, even though it's supposed to be a laser weapon, chances are it's not a laser. If this occurs in a dark area, it will appear brighter as opposed to a laser being used out in the open on a sunny day.

So, in order for a laser beam to be a true laser in every sense of the word, it must follow these criteria. Of course, the parts about the laser beam appearing as a straight, instantaneous beam, or bending, or reflecting are all dependent on special circumstances, such as if the laser is a diode or gas laser, or if there are particles in the air, or if the person who is dodging or reflecting a laser has some special vision (seeing in the infrared spectrum, for example). Otherwise, the main focus should be only on 2. and 3.

References

1. Xemnas Final Battle Kingdom Hearts 2
2. "This robotic guardian can be found in various places. They have a long neck that is usually withdrawn, but will extend it and attack with a laser beam." Metroid II: Return of Samus, p. 28
3. "Spazer Laser Beam A three way beam with an extremely wide focus is fired when this weapon is discharged." ibid., p. 22
4. FF8: Quistis Limit Break
5. What Is a Visible Laser?
6. Jonny Quest The Mystery of the Lizard Men
7. Afro Samurai v.s. Afro Droid
8. Kirby can fire a laser beam! This beam will bounce off slopes, so try it in many places! (Kirby's Adventure)
9. Light Amplification by Stimulated Emission of Radiation. And it ricochets off hills, too! (Kirby: Nightmare in Dream Land; Kirby & the Amazing Mirror)
10. Kirby: Nightmare in Dream Land -3- Laser Kirby

Here are some videos on what lasers look like.

Instant Laser Coffee
DPSS Industrial Green Laser System 2 Watt Cutting CD Case
DPSS LASER 532nm 2000mW (2W) Burning and Cutting Test Power
2W 445nm Blue Laser versus 11 CD Cases
Laser Diode RPL (Real 260 mW) Class III B 13 Match Burn
Insanely Powerful 2000mW Blue Laser Destroying Stuff

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Understanding reaction time.

When one speaks about reaction time on FactPile, and perhaps other message boards, the words "supersonic", "hypersonic", "high hypersonic", "relativistic", or "FTL" are used to refer to a character's RT. The more appropriate thing to refer these things by is "millisecond" (ms), or "microsecond" (μs), or "nanosecond" (ns). A character who can dodge bullets would fall under ms RT. Yeah, speaking of RT this way makes dodging bullets look like nothing because humans react to things by the millisecond. I like to differentiate here, however, by calling it "improved reaction time", but only with respect to ms RT, nothing else.

Another thing when it comes to RT is that people tend to ask under what Mach number that RT would fall under. The thing is, RT doesn't fall under Mach's number. I'm guilty of doing this as well, but I realized this was like the whole "supersonic", "hypersonic", &c. RT. Why doesn't RT fall under Mach's number? Because, Mach's number is applied only to speed, not time, and RT is all about time, not speed. Yes, speed is involved, but only because in order to figure out the time it took for an object to travel, it has to be distance divided by speed (t = d/s).

Now one of the more important things about RT is also where the character is located, and where the object is initially located before it is fired. Let's say someone, Person A, is standing 152 meters away (500 ft.) from Person B. Person B has a gun that fires bullets at 457 m/s (1,500 ft/s). He fires a round at Person A. Since we know the distance between the two and the speed the bullet is traveling, we would take t = d/s and learn that Person A would need to react in less than 0.202 seconds, which is the same as 20.2 ms.

Say Person A dodges. That's great. We have an estimate of his RT. The problem I see at FP and other message boards like it is that if a character can dodge bullets, this means he or she can dodge bullets at any range, even possibly point-blank (0.91 m.; 3 ft.). Going back to Person A, all we know is that if he is at 152 meters or farther, he can dodge a bullet traveling 457 m/s. This also means he can dodge slower bullets at a closer range, but that should also be tested anyway to see if Person A's RT is 20.2 ms or higher. If Person A can dodge a bullet traveling 457 m/s at 152 meters, it doesn't mean he can dodge it at 61 meters (200 ft.), unless proven.

To truly find out how fast a character can react to a projectile or an attack, the best method would be to have that character at point-blank or closer. Otherwise, the only reliable estimate is from the distance and speed already demonstrated. Of course, this can possibly cause outliers. What I mean is that if a character is at point-blank range and dodges a bullet traveling 457 m/s earlier on, but later demonstrates less-than-stellar RT feats, then the lower RT should be called out on. And by the way, lower RT is better because it means the person required lesser time to react.

Now here is a link I left for light. Light travels 0.3048 m. (1 ft.) per nanosecond. The link shows what it would be like at a pico- level, I believe. Enjoy!

Femto-Photography: Visualizing Photons in Motion at a Trillion Frames Per Second
Last edited by Proto-Mind on Fri Sep 21, 2012 6:15 pm, edited 5 times in total.
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Re: Lasers and Reaction Time

Postby Captain Epic » Sun Jul 22, 2012 10:38 pm

This thread deserves more attention.
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Re: Lasers and Reaction Time

Postby Stealthranger » Sun Jul 22, 2012 10:40 pm

Kind of inspired to make my own thread....
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Re: Lasers and Reaction Time

Postby Proto-Mind » Thu Aug 02, 2012 9:04 pm

I'm thinking about updating the first post, and perhaps adding something else to address.
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Re: Lasers and Reaction Time

Postby Matapiojo » Fri Aug 03, 2012 6:42 am

Very useful. Added into the sticky.
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Re: Lasers and Reaction Time

Postby Proto-Mind » Fri Aug 03, 2012 9:58 am

Wow, Matapiojo! What an honor! :oops: I appreciate that very much.
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Re: Lasers and Reaction Time

Postby Matapiojo » Fri Aug 03, 2012 10:16 am

Credit where credit is due, and all that. Any other viable debating tool/aide you bring to our attention will get the same treatment.

Good job.
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Re: Lasers and Reaction Time -Updated 9/5/12-

Postby Proto-Mind » Wed Sep 05, 2012 11:01 am

I updated the OP, everyone. If you're interested in reading my thoughts on reaction time, feel free to check it out.
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Re: Lasers and Reaction Time -Updated 9/5/12-

Postby Dualgunner » Sun Oct 28, 2012 8:24 pm

I looked up "Reaction time" on wikipedia, and learned something interesting.
http://en.wikipedia.org/wiki/Reaction_time

"Response time is the sum of reaction time plus movement time.

Usually the focus in research is on reaction time. There are four basic means of measuring it:
Simple reaction time is the motion required for an observer to respond to the presence of a stimulus. For example, a subject might be asked to press a button as soon as a light or sound appears. Mean RT for college-age individuals is about 160 milliseconds to detect an auditory stimulus, and approximately 190 milliseconds to detect visual stimulus.[2] The mean reaction times for sprinters at the Beijing Olympics were 166 ms for males and 189 ms for females, but in one out of 1,000 starts they can achieve 109 ms and 121 ms, respectively.[3] Interestingly, that study concluded that longer female reaction times are an artifact of the measurement method used; a suitable lowering of the force threshold on the starting blocks for women would eliminate the sex difference.

Recognition or Go/No-Go reaction time tasks require that the subject press a button when one stimulus type appears and withhold a response when another stimulus type appears. For example, the subject may have to press the button when a green light appears and not respond when a blue light appears.

Choice reaction time (CRT) tasks require distinct responses for each possible class of stimulus. For example, the subject might be asked to press one button if a red light appears and a different button if a yellow light appears. The Jensen box is an example of an instrument designed to measure choice reaction time.

Discrimination reaction time involves comparing pairs of simultaneously presented visual displays and then pressing one of two buttons according to which display appears brighter, longer, heavier, or greater in magnitude on some dimension of interest.

Due to momentary attentional lapses, there is a considerable amount of variability in an individual's response time, which does not tend to follow a normal (Gaussian) distribution. To control for this, researchers typically require a subject to perform multiple trials, from which a measure of the 'typical' response time can be calculated. Taking the mean of the raw response time is rarely an effective method of characterizing the typical response time, and alternative approaches (such as modeling the entire response time distribution) are often more appropriate.[4]"

This gives birth to a whole new idea in Reaction Time: What kind of reaction time is it, and, response time.
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Re: Lasers and Reaction Time -Updated 9/5/12-

Postby Proto-Mind » Sun Oct 28, 2012 8:54 pm

So perhaps response time would be the best term to use, as opposed to reaction time when it comes to dodging. I might add some new information in the OP on the variables for dodging things.
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