pmb

'Closed under addition' is used all the time.

That's also part of linear algebra, which I use quite often.

Actually, pmb, the distinction is worth making.

 

One property of a field (from the mathematical definition not physics) that is useful (vital even) in physics is that the field is closed under addition.

As an undergraduate one of my majors was mathematics. One of the required courses was abstract algebra. While I'm sure that group theory and all the stuff about fileds and rings is useful somewhere in physics, I myself have never had cause to use it need it in my studies an research.

Edit: (Never mind.)

I collect 10$ from everyone who fallaciously says that to me.

 

Do you except cyberbucks? If so then here {cha-ching! - $11.00}. I added a doller for prompt service.

A proper and modern picture was given: Light is made of particles named photons. Under certain circumstances a collection of photons behaves, collectively, as something that we call a wave. The wave theory is an approximation to the underlying quantum theory of particles.

The wave characteristics of particles also applies to single particles. When a single particle approaches a step potential part of the wave is transmitted and part is relfected. That's the wave character manifesting itself. A wave function can apply to single paricles. A wave can be a continuous superposition of waves to give a wave packet too. That wave packet can scatter off of a point potential like the potential associated with a nucleus.

You really seem to know absolutely nothing about cosmology, astronomy, or physics in general. I am quite suspect of your claim to be an electrical engineer. If it's true, it's a condemnation of the science curriculum at whatever institution you attended.

Engineers rarely take more than Physics IO, II and III. Even then they quickly forget most of it. And those courses don't even touch base with astronomy or cosmology.

In your opening post you are concerned that another poster on another forum said "you seemed to be attacking him".

That's not quite right. I wasn' concerned about his actions. That was taken care of in the other forum. I asked the following question

I'd like a second opinion on something I was faced with elsewhere.

and after presenting the example I inquired

Would you say that this is an ad hominem?

...

What do you do when you get an ad hominem reply?

And that is the essenf this thread. And I've been nothing except very polite' date=' reasonalble and logical in all my reponses and inquiries.

The example is completely anonymous. Both the name of the person and the name of the forum is kept a secret so as to esure that this doesn't get at all personal. In fact when someone, who also frequents that forum, mentioned his name I promptly asked then to delete the name from their post, and then were kind enough to do so. This is [i']purely[/i] an intellectual exercise.

you assert, was an ad hominem.

That's correct. But to be precise, he said

ever since you re-joined this forum you have seemed eager to prove me wrong every time I opened my mouth.

or in short You're out to get me. To me, when someone says You're out to get me its an attack on my character. His response had nothing to due with my original argument, i.e. him that a particle with rest mass can't move at the speed of light.

In the course of this discussion I gained a precise knowledge of what an ad hominem is and as such I now know that it was a personal attack aka ad hominem.

A few posts back you declare that swansont "is impatient".

I quickly deleted that comment so I will not discuss it. I later said that I his comment expresses frustration since the purpose of the comment Oh, for crying out loud. is to express frustration. I even looked it up just to make sure. And I gave that link - http://en.wiktionary.org/wiki/for_crying_out_loud

you don't say he seems impatient or appears to be impatient. You are absolutely convionced: he is impatient.

Its not a subjecctive comment but an objective one.

Impatience is generally seen as a negative quality. You are attacking his character.

Nope. Its not an attack when there's no question that its frustration. swansont will probanbly agree that he was frustrated, hence his remark. That can't be used as a premise to claim that my observation of that was an attack on his person. In essence all I said was Why are you impatient which I changed to Why are you frustrated?. Those aren't attacks on a person by any means.

Now to the heart of the matter: have you considered just taking a step back and appearing to behave like a mature human being?

Please don't take this conversation into a negative mode. There's just no call for that kind of thing here.

The purpose of this thread was to distinguish whether something was an ad hominem or not. I just happened to use a real life example. The persons name and the forum's name was intentionally left out of this thread so as to keep it a secret. This has nothing to do with that person or that forum but merely the definition and example of ad hominem.

Before this thread I wasn't 100% clear on what an ad honinem was. Now I cleary know all about them. The rest of my responses were answers to questions posed of me and commenting on others responses.

This is an exercise in an intellectual analysis of a particular part of cogent arguments. In particular its an analysis of the fallacy known as the personal attack aka ad hominem. I've been quite polite and logical throughout this thread, avoing negative deviations from the main topic.

I've been reading the book Practical Logic: An Antidote for Uncritical Thinking. Its part of my study of critical thinking and constructing cogent arguements and recogning logical fallacies. The personal attack which I used as an example was just that, an example. I created another thread as a continuation of this study. The name of that thread is Critical Thinking Skills.

Perhaps: not understanding physics i couldn't comment on whether the first five responses he made were actually arguing the point, but at least it appears he is attempting to do so.

No. The first five responses were explaining why his thread served its purpose without the part that I told him was wrong. Those responses had absolutely nothing to do with my argument.

I didn't. "you seem to be picking on me" (paraphrased) is not attributed to you, it's the supposed ad hom that you were orginially inquiring about. Why is that not simply an observation?

Sorry. I don't want to give more life to something which was merely an inquiry.

Wait, what?

Recall, again what a personal attack is

Whenever we attack a person instead of his or her argument, we commit a form of the fallacy known as personal attack.

That's quite different than a simple attack on a person? An attack on a person need not have anything to do with a argument. It could just be anger at a person. You seem to be reading it literally where in fact its taken as a single term which has the above meaning.

For what it's worth i do not think it's an ad hominem attack, it seems to be in addition to, not instead of, an attack of the actual argument.

The actual argument was me explaining that a particle with rest mass can't travel at the speed of light. His character assasination never mentioned that argument. That's what makes it a personal attack aka ad hominem.

Dark matter isn't predicted by the standard model, and it's more than reasonable to think that DM may consist of particles.

Also, I wouldn't say that the properties of spacetime couldn't be explained by QM. E.g. nobody has ever used QM to derive the expression for time dilation or length contraction. Black holes can't be explained by QM either. Myself, I never use wide sweeping generalizations like that. There are always exceptions to every rule such as the ones I mention here.

I thought it was about measurement: when you measure it in order to prove it is a particle, you find it is a particle, and when you measure it in order to prove it is a wave, you find it is a wave.

Young's double slit experiment is a good example of the wave-particle duality. If you set up an ensemble of such experimental set ups and let just one photon go through the double slit and then compare all the results then (1) in each individual set up you'll see that only a single photon is detected on the screen and (2) the collected results will show the interference phenomena. It's pretty cool!

Let’s try a thought experiment; of course you can use mathematics if you want to also.

 

Let’s remove the earth and place it in another universe that is absolutely void and lacking energy of any type, absolute cold at absolute zero.

 

How long do you think it would take the entire earth from atmosphere, oceans, crust right down to the very core to freeze solid (This might not be the right expression) or put another way, reach the now almost the absolute zero of the empty universe it now inhabits?

 

Alan

That's a very complicated problem to solve. It depends on the thermal properties of the various kinds of matter which the earth is made up and how that matter is distibuted It's possible to solve it but IU sure don't know how to do it. One needs to be skilled in thermodynamics to solve a problem like that and thermodynamics was always my worst subject.

Why do scientist, religion and quantum physicist talk bad about each other??

I believe that is an inaccurate perception. I think about 35% of all physcists believe in God. The 65%who don't certainly don't all speak badly about religion.

While on the religion side most scientist denote the existence of god never thinking twice that maybe the belief in god gives someone hope in where, " the leaders" of this world can't.

Sure they do. I believe that's a false impression that you gained somewhere/somehow. Perhaps from the few who are very noisey on that kind of thing. I'm a physicist and I'm a Christian and I certaintly don't think that way. Even when I wasn't religious I never thought badly about people who were religious

Take this away from the believer in god, they may end up an abuser "again", a hater "again" etc.. Maybe science and or school was too difficult for the believer, so they chose an idolization such as god to have something to believe in.

Oh, I don't know about that. I tend to disagree on that point.

Maybe those whom believe in god like homosexuals, lesbians, abused women, foster children, minorities and etc, were never "welcomed" in this world, made fun of , placed as slaves, irraticated from the face of this world, had "laws" against them and etc. And maybe now this god gives them inspiration.

I believe that such people believed in God but perhaps don't believe in the Bible. A lot of people seem to put them hand in hand. I think a lot of people who see a believed in God automatically assume they must be judeo-christian, which obviously isn' implied merely because one believes in God, although I'd say that the majority does think that.

Below is my personal list by rank, please give yours?

In my opinion Jesus is the most influential person in the history of the world.

Quote: Why is it not enough?

 

 

 

In order to get the 13.1 light year distant, the galaxy should travel almost at the speed of light.

 

This is unlogical.

 

Therefore, in order to get to this distant, the time should be much longer than the time from the Big Bang.

 

You do understand, don't you, that its not that the galaxy is moving through space, its just that there is space being created inbetween gallaxies and that yields an effective increasing distance at a rate which makes the distance between some gallaxies appear faster than the speed of light?

The obvious conclusion is that both the corpusculer and wave models are inadequate by themselves and that the true nature is something with some of the characteristics of both plus perhaps properties we have yet to uncover.

 

Why is this so hard to swallow?

Wonderful. Well said sir!! So well put that it brings a tear to me eye!

I found where Feynman explains in QED that electrons have a wave-like property. It's on page 84.

In 1924 Louis de Broglie found that there was a wavelike character associated with electrons, and soon afterwards, C.J. Davisson and L.H. Germer of Bell Laboratories bombarded a nickel crystal with electrons and showed that they, too, bounced off at craxy angles (just like X-rays do), and that these angles could be calculated from De Broglies formula for the wave-length of an electron.

And just how many times in the past have scientists and thinkers made this claim that they know everything?

 

Mendelev and his mates were wrong about the number of elements

 

Kelvin was wrong about the cooling of the earth....

 

I suggest that anyone making such an extravagant claim is suffering from a severe case of bloaty head.

I think that its a fair way to speak though. It would become cumbersome to keep repeating according to the laws of physics as they are presently known ..... I always take that as a given and that the scientist who says those things understands that.

Did you read my link sir?

 

It's ok to wrong, I've been wrong quite a few times in my lifetime.

 

The wave function is certainly not a myth. Quantum mechanics has been built from such things, and as you know, quantum mechanics is all about experimental evidence.

Consider a large number of Young's Double Slit experiment. Allow just one photon to go through the slit. It will be detected on the screen behind it by the "click" of one photon detector. If you were to look at the ensemble of all those experimental setups you'd see that there is an interference phenomena present. Its for this reason that its said that there is a wave-particle duality and why Feynman said "It's like neither.'

Note: The quote from Feynman's QED only addresses light/photons. It makes no mention of electrons. I have the check the context. What page is that on?

Well, this post arrived! Nice to be appreciated. Are you sure you remember to hit the "Post" or "add Reply" button after typing? (Possibly out of sight below).

I do have a psychological disorder which affects my memory. ADD etc. It's terrible. I lost my keys again today the third time within the last month. It sucks big time. So sure, that could be the case. Or maybe I only hit preview! Yeah! That's the ticket! I think that's what I did! Yay! I figured it out. Thanks.

"Wave-particle duality" is often a misleading name. Electrons and photons are quantum mechanical particles. They do not behave in the same way that classical particles do, and indeed can't really be explained in terms of anything familiar to you. The particles have an associated "wave function," which is essentially a wave of probability. The wave function gives the probability of finding the particle in a given region of space, and it exhibits normal wave characteristics (i.e. it can interfere, etc.). Asking whether or not it is a particle or a wave is nonsensical.

I love the way Feynman explains it in his Lectures. In V-II page 1-1

"Quantum mechanics" is the description of the behavior of matter and light in all details and, in particular, of the happenings on an atomic scale. Things on an atomic scale behave like nothing that you have any direct experience about. Thet dot behave like waves, they do not behave like particles, they do not behave like clouds, or billiard balls, or weights on springs, or like anything that you have ever seen.

Newton thought that ligt was made up of particles, but then it was discovered that it behaves like a wave. Later, however (in the beginning of the twentieth century), t was found thalight did indeed sometimes behave like a particle, and then it was found that in many respects it behaved like a wave. So it really behaves like neither. Now we have given up. We say: "It i like neither."

Someone once coined the term wavicle (http://en.wiktionary.org/wiki/wavicle) as a comprimise but it never really took. Today physicists ue the term "particle" not because they behave like particles, but because there is no other term and its good enough since nobody ever gets confused by it and actually thinks that photons and electrons are "really" particles. Although I'm sure there are a lot of people who are confused on this point.

The wave function, like any mathematical quantity in physics, is a quantity that has the physical meaning that the square of the magnitude is related to probability. For a continuous wave the square of the magnitude is a probability density.

Thanks Juangra.

But is electron present as a standing wave or as a particle in the atom??

I have read in some book, that it is still a mystery and we can't figure out what goes inside the atom..

The thing about quantum mechanics is that you can't talk about what a system is doing until you make a measurement. Asking about an electron is doing when it hasn't been observed is a meaningless question in QM. There are states in the atom which stationary states. Once you measure owhat state its in then you can make a statement about it.

This is wonderful. Everyone chipping in with other ways of thinking is a great way to add to the spirit of this page. I want to thank everyone for their contribution and sat "Keep'em cummin".

Note: Somethings wrong. Several times now I've posted a message only later to see it missing. What's going on?

So how is it that "you seem to be picking on me" (paraphrased) isn't an observation?

Please don't put words into my mouth. The thought of "picking on me" never entered my mind. Btw, I made a mistake. Oh, for crying out loud is not an attack, its meant to show the emotion of either frustration, exasperation, or annoyance. See http://en.wiktionary.org/wiki/for_crying_out_loud.

Used to express frustration, exasperation, or annoyance

In any case I deleted that comment because I thought that it was unwarrented. Sometimes we all say things we regret later. I've decided to delete those things when I can so as to be as polite as I can. I imagine that's fine with you?

You just got done telling me that any personal attack is ad hominem — that they are synonyms.

That's correct. They are. And yo used it wronig. The only way I Can see to resolve any misunderstanding with the definition is to realize that a personal attack is not simply not an attack on a person. They are not the same thing. That's clear from the definition.

Note: I've already said I'm done with ad hominems so I won't adress them again with you. I believe that you and have already paved that road.

Hmm. Ad hominem. (according to your definition)

You are very wrong. So wrong that I'm quite surprised by this response. Let us, for the sake of argument, say that it was an attack on you (which it really wasn't. It was an observation). It's not an ad hominem because its lacking that part instead of the arguement since I addressed your argument. And just because I observed that you seemed impatient it doesn't mean that its a personal attack. Are you telling me that Oh, for crying out loud. cannot be interpreted as you being impatient? And are you saying that when someone observes you being impatient and mentions it that you think its an attack? If yes then how so?

And I can just as well claim that your commentOh, for crying out loud is a attack on me because that kind of thing is only said to people when the person saying it is impatient and that its purpose was to insinuate that I'm "thick" in some way.

Once again, you've ignored the entire qualifying part of the definition.

I didn't ingnore that at all. I did a detailed analysis in a previous post and you for all practical purposes ignored it. You mad no of my detailed analysis. You're merely repeating your claim now.

"attacking the character or circumstances of an individual who is advancing a statement ..

Which is what the opponent did by claiming I was out to get them. That was an attack on my character.

..or an argument instead of trying to disprove the truth of the statement or the soundness of the argument." is not identical to "attacking the character or circumstances of an individual who is advancing a statement or an argument"

The criteria of an ad hominem is Whenever we attack a person instead of his or her argument. I've explained, many times now, that the opponent, instead of addressing my assertion that v = c does not hold for partilces with non-zero rest mass, attacked my character by claiming I was out to get him. It's that simple and that's an ad hominem, by definition.

We are obviously not getting anywhere. I've already explained in detail how precisely that was an ad hominem and you don't address that, but address something that I've never said. At this piint I don't see that anything else I can say will resolve our differences so I must cease my contribution to this argument. We will simply have to agree to disagree.

Meh. I could recite plenty ad hominem attacks since I have been here. Others been so fantastically forthcoming that they haven't even been punished.

Aethelwulf - Take my word for itmy friend, don't continue. Any attempt at explain yourself and your point of view, regardless of the circumstances, always looks bad. Nobody can win under such circumstances. Just a friendly suggestion.