See An Electron Lately?
This is not about seeing an electron, but rather, the notion that seeing something with our eyes is the end-all requirement for the validity of anything. I will show that our human eye, as a light detector, is NOT a very good detector at all in many aspects, and thus, using it as the standard detector to validate anything is utterly irrational.
The motivation for this is that I often see a lot of ignorant statements on PF that either questioned, or dismissed something just because we can't "see" it. A prime example that often pops up is the claim that we "haven't seen an electron".
http://www.physicsforums.com/showpos...28&postcount=3
http://www.physicsforums.com/showpos...5&postcount=65
http://www.physicsforums.com/showpos...93&postcount=7
http://www.physicsforums.com/showpos...4&postcount=39
http://www.physicsforums.com/showthread.php?t=460209
http://www.physicsforums.com/showthread.php?t=145501
I could go on and on, but you get the idea. So now, I will show that "seeing" is over-rated!
Of course, there are several ways to attack such stupid (yes, STUPID) arguments. The first is the question on what we mean by "seeing". Often, most people simply meant seeing something with the human eyes. But what exactly does that mean? If these people were to think carefully, it means a series of events that must occur: (i) visible light from some source hits an object; (ii) light from that object travels to our eyes (iii) our eyes then transmit electrical impulses to our brain (iv) we detect that object visually. That, my friends, is what is meant by seeing with our own eyes.
Next, by the above description, it is clear that our eyes can only see electromagnetic radiation, and not only that, it can only see it within the visible spectrum, which isn't very much. Thus, if something either does not emit EM radiation, or if the radiation is outside of the visible spectrum, we can't see it! Let's go back to our friend the electron. It is a charge particle. Our eye cannot "see" it even if it hits our eyeball! But can we still see it? Sure we can! Enter a cloud chamber! When an electron, especially high energy ones, moves through a cloud chamber, it ionizes some of the air/gas/water vapor molecules. This creates a nucleation site for water vapor condensation, leaving a cloud trail in the chamber. There, you have seen an electron. One could also argue that our eyes are not the only "detector" around. We can also use our other senses. We can't see wind, but we can hear and feel the moving air. We can't see heat/IR, but we can certainly feel it on our skin. Our eyes is only ONE of the "detector" that came with our bodies.
And speaking of the human eyes as detectors, anyone who has done anything with detection instruments can tell you that the eyes is a very bad detector in many cases. Sure, it has a very high spatial resolution, but man, it sucks everywhere else. For example, look at this figure that shows the sensitivity of the human eye over a range of frequency and also its response sensitivity.
Compare to other devices, the human eye has 2 very clear shortcomings: (i) the range of wavelength it is responsive to is extremely small; and (ii) its sensitivity (i.e. quantum efficiency, or QE) is quite low. It has a peak QE of ~1% at around 550 nm. What this means is that out of 100 photons that come in, it can detect, on average, only 1. Compare the range and QE of Vidicon and CCD and our eye is a very poor light detector! And this is what some people are using as the sole criteria of what's real and what isn't? Is this rational?
Next, we will deal with the response time, which will produce the time resolution, of the human eye. We all know that when we go see a movie, it is nothing more than a series of still-image frames, moving past us fast enough that we do not see its motion, but rather see the image as being continuous. Standard movie frames (at least till all the new advancements in movie projection) used to go at 24 frames per second (FPS). This translates to 0.04 second per frame. We also know that the human visual system holds an image for about 0.02 second. It means that anything that comes into our visual system faster than 0.02 second will not be perceived as being distinct. So the 0.02-0.04 second is roughly the time resolution of the human eye.
Now, compare this to other devices. I've listed before some typical photocathodes used in accelerators. Note the time responses for the various types of photocathodes. The worst of these are in nanoseconds. This is still order of magnitudes shorter than the human eye! One example is GaAs, which is a common photocathode use in both accelerators and photodetectors. On Pg. 25 of this presentation, one can see measurement of the time response. The full-width-at-half-maximum of this photocathode is of the order of picoseconds!
So the human eye is not only a bad detector in terms of its bandwidth range and also in terms of sensitivity, it is also a very SLOW detector and can't separate a series of event occurring faster than 0.02 second!
As with many things that a lot of people spew without thinking, the debunking of such things often are quite simple IF one has a little bit of knowledge, and the the ability to analyze the situation. Analyze what it means by "seeing", and then analyze the "detector" that is being use as the criteria. And apply such techniques to the pile of manure that one often hears in the media from politicians, etc., assuming you have such patience. If you are using "seeing" as your sole criteria to accept the validity of something, then you need to seriously examine this "detector" that you hold so highly, because it is a very poor detector!
Zz.
The motivation for this is that I often see a lot of ignorant statements on PF that either questioned, or dismissed something just because we can't "see" it. A prime example that often pops up is the claim that we "haven't seen an electron".
http://www.physicsforums.com/showpos...28&postcount=3
http://www.physicsforums.com/showpos...5&postcount=65
http://www.physicsforums.com/showpos...93&postcount=7
http://www.physicsforums.com/showpos...4&postcount=39
http://www.physicsforums.com/showthread.php?t=460209
http://www.physicsforums.com/showthread.php?t=145501
I could go on and on, but you get the idea. So now, I will show that "seeing" is over-rated!
Of course, there are several ways to attack such stupid (yes, STUPID) arguments. The first is the question on what we mean by "seeing". Often, most people simply meant seeing something with the human eyes. But what exactly does that mean? If these people were to think carefully, it means a series of events that must occur: (i) visible light from some source hits an object; (ii) light from that object travels to our eyes (iii) our eyes then transmit electrical impulses to our brain (iv) we detect that object visually. That, my friends, is what is meant by seeing with our own eyes.
Next, by the above description, it is clear that our eyes can only see electromagnetic radiation, and not only that, it can only see it within the visible spectrum, which isn't very much. Thus, if something either does not emit EM radiation, or if the radiation is outside of the visible spectrum, we can't see it! Let's go back to our friend the electron. It is a charge particle. Our eye cannot "see" it even if it hits our eyeball! But can we still see it? Sure we can! Enter a cloud chamber! When an electron, especially high energy ones, moves through a cloud chamber, it ionizes some of the air/gas/water vapor molecules. This creates a nucleation site for water vapor condensation, leaving a cloud trail in the chamber. There, you have seen an electron. One could also argue that our eyes are not the only "detector" around. We can also use our other senses. We can't see wind, but we can hear and feel the moving air. We can't see heat/IR, but we can certainly feel it on our skin. Our eyes is only ONE of the "detector" that came with our bodies.
And speaking of the human eyes as detectors, anyone who has done anything with detection instruments can tell you that the eyes is a very bad detector in many cases. Sure, it has a very high spatial resolution, but man, it sucks everywhere else. For example, look at this figure that shows the sensitivity of the human eye over a range of frequency and also its response sensitivity.
Compare to other devices, the human eye has 2 very clear shortcomings: (i) the range of wavelength it is responsive to is extremely small; and (ii) its sensitivity (i.e. quantum efficiency, or QE) is quite low. It has a peak QE of ~1% at around 550 nm. What this means is that out of 100 photons that come in, it can detect, on average, only 1. Compare the range and QE of Vidicon and CCD and our eye is a very poor light detector! And this is what some people are using as the sole criteria of what's real and what isn't? Is this rational?
Next, we will deal with the response time, which will produce the time resolution, of the human eye. We all know that when we go see a movie, it is nothing more than a series of still-image frames, moving past us fast enough that we do not see its motion, but rather see the image as being continuous. Standard movie frames (at least till all the new advancements in movie projection) used to go at 24 frames per second (FPS). This translates to 0.04 second per frame. We also know that the human visual system holds an image for about 0.02 second. It means that anything that comes into our visual system faster than 0.02 second will not be perceived as being distinct. So the 0.02-0.04 second is roughly the time resolution of the human eye.
Now, compare this to other devices. I've listed before some typical photocathodes used in accelerators. Note the time responses for the various types of photocathodes. The worst of these are in nanoseconds. This is still order of magnitudes shorter than the human eye! One example is GaAs, which is a common photocathode use in both accelerators and photodetectors. On Pg. 25 of this presentation, one can see measurement of the time response. The full-width-at-half-maximum of this photocathode is of the order of picoseconds!
So the human eye is not only a bad detector in terms of its bandwidth range and also in terms of sensitivity, it is also a very SLOW detector and can't separate a series of event occurring faster than 0.02 second!
As with many things that a lot of people spew without thinking, the debunking of such things often are quite simple IF one has a little bit of knowledge, and the the ability to analyze the situation. Analyze what it means by "seeing", and then analyze the "detector" that is being use as the criteria. And apply such techniques to the pile of manure that one often hears in the media from politicians, etc., assuming you have such patience. If you are using "seeing" as your sole criteria to accept the validity of something, then you need to seriously examine this "detector" that you hold so highly, because it is a very poor detector!
Zz.
Total Comments 10
Comments
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Well said.Posted Jul29-12 at 05:38 PM by Nano-Passion 
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Electrons don't exist because nobody has seen them. Using the same logic, I can say you probably don't exist because I haven't seen you.
Posted Sep24-12 at 07:16 AM by Byron Chen 
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That logic doesn't quite work. While you haven't seen me, someone else has.
With the electron, NO ONE has seen it, according to the statement that I've heard. So here, your analogy breaks down.
Zz.Posted Sep24-12 at 10:37 AM by ZapperZ
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A slightly better analogy is convicting somebody of a crime based on evidence, but without any actual witnesses. Perhaps nobody saw that person commit the crime, but there could be the suspect's fingerprints left at the crime scene, some of the victim's belongings found in possession of the suspect, and traces of the victim's blood found on the suspect's clothing.Posted Sep25-12 at 06:52 AM by Redbelly98
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That is a really good analogy.
Posted Nov4-12 at 02:50 AM by Byron Chen
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Seeing to believe an object's existence within itself suggests that every objects are observable with the limitations of human eye. Seeing the object's influences and effects is a different story. Infact only such 'effects' has the ability to predict the existence of an object.
for example, The theoretical prediction of quark or the so called strange particles by Murray Gell-Mann was only a postulate at the time inorder to complete the picture. This postulate was proved when it was discovered in a collider. anyway does this suggest we need to see it to believe it. what if we didn't 'see' it. Even in a collider we are not taking pictures to 'see' it. a particles influence is detected and converted (data) to visible form, like a computer simulation.
We can't see Doppler effect, we hear it. we can't see radio waves we see its influence.
but the dominance of eye in scientific study might be because of the influence it has in visual calculation of fundamental units, analyzing mathematical graphs, patterns and spectrum and much more wider unique areas.Posted Nov26-12 at 12:20 PM by caspernorth
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"Blessed are those who have not seen and believed"
Applies to science too :)Posted Feb23-13 at 06:48 AM by dbmorpher
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Nonsense.Quote:Quote by dbmorpher
"Blessed are those who have not seen and believed"
Applies to science too :)
Zz.Posted Feb23-13 at 12:39 PM by ZapperZ
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There is a huge temptation to confuse 'seeing' with composing a conceptual model of a scene or object in our brain. Close your eyes or look to one side of something and the model in your head is still there. You have an excellent conceptual model of the inside of your mouth - which you haven't 'seen' properly, ever. It's down to your exploring it constantly with your tongue. It's so good that you can chomp on a piece of meat without thinking about it but without biting your cheek, which is a mm away. That's much cleverer than chopping onions with a sharp knife - which demands a lot of concentration to avoid cutting yourself.
A person who has been blind from birth can build up a perfectly usable 'picture' of the spatial relationships in a room. Likewise, we do not need to experience something with our eyes (some non-optical thing) in order to have a perfectly valid and reliable knowledge of its properties.Posted Feb27-13 at 11:21 AM by sophiecentaur
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It is very unfair to include my post among the 'stupid' ones. I never claimed that the electron theory was invalid. I simply stated that when you claim to have seen something, you better well have seen it. I know you are naked under your clothes, but that doesn't justify me saying that I saw you naked. That is what I posted, read it.Posted Mar24-13 at 05:04 PM by Jimmy Snyder
