It certainly can be, depending on demeanor and context. Not challenging someone’s deeply held relief when there is no compulsion or context-appropriate invitation to do so is always the polite thing to do.
Granted, posting “I believe X” in GD or similar forum invites challenge, within the constraints of board rules. Simply living as a believer of X does not invite such challenge.
Noether’s theorem says that “any differentiable symmetry of the action of a physical system has a corresponding conservation law.” If the system is time invariant, then something will be conserved, which we could call “energy”. The mathematical form of this energy wouldn’t be the same as in the Lagrangian/Hamiltonian universe, but that hardly seems relevant in a debate where AClockworkMelon’s friend uses “energy” to mean “life force” 
Nobody said fightin’ ignorance was always going to be polite. 
**Oakminster **how do you know the OP is the one doing the challenging?
Damned rude to make these sorts of assumptions if you ask me.
You might want to read the last part of the OP’s post #20. The OP’s friend doesn’t sound like a victim.
Er, sure, but, unless I’m mistaken, Noether’s theorem only concerns a specific kind of “physical system”: one specifiable via a principle of stationary action; that is, as some law of the form “The derivative with respect to some function q of the functional given by the integral over t of some function L(t, q(t), q’(t), q’'(t), …) is 0”. But is there any natural reason laws of physics should have to be formulable in this manner? That they generally happen to be is interesting, but one could certainly at least counterfactually imagine laws not expressible in this form. Your own Wikipedia link notes that Nother’s theorem “does not apply to systems that cannot be modeled with a Lagrangian”. So, that’s all my point was: I think it’s misleading to say, without further qualifiers, that any notion of time-invariant physical laws leads to a concept of conservation of energy, since this isn’t quite true in as great generality as anyone not already familiar with the result would think was being stated. Rather, the result concerns only those time-invariant physical laws which are also specifiable in the above manner as a solution to a particular kind of problem in the calculus of variations, which was what I meant by “the Lagrangian/Hamiltonian style”.
(But I’m happy to be shown wrong or misguided and to gain a greater understanding of Noether’s theorem, if at all possible, since, to be honest, I don’t really know that much about it)
Heh, yeah, I guess this is all a bit off-track. But perhaps pointing the friend at this thread will show them just how misguided they were to assume they understood what physicists meant by “energy”.
I thought my disclaimer would be enough. Guess not.
Lol, she’s not a victim. If I thought she felt victimized I wouldn’t bother her about it.
There is such thing as a life SPAN. Who you are permanently exists between two temporal coordinates. The passage of time is something we experience while alive.
Damn, for a concept so simple, that sounded deep as hell.
I don’t understand what you’re trying to say. Yes, I know that there’s a lifespan. All that reflects is how long it takes before your body starts decomposing (interestingly, this seems to be caused by genes that trigger the breakdown- the reason natural selection hasn’t gotten rid of these genes is because they affect us when we’re old, after we’ve already passed on our genes through breeding - were we to discover which genes did this and what precisely triggered them, that might open the door to theoretical immortality). But who you are permanently exists between coordinates?? I don’t know what you’re talking about. 
By analogy: when you reach the end of the book you’re reading, well, that’s the END of it. You put it back on the shelf and take down another book to read. The book you put back is still in existence, on the shelf, as are all the books. The passage of time as it exists between the covers of the book you’re reading now is only real to you, the reader, while you’re reading that book. When you put it back on the shelf, all the books exist in simultaneity and none of them has “come to an END”. And you will eventually read them all. In fact, you’ll eventually RE-read them all.
Don’t make too much of it, it’s just an analogy. Spiritual truths are not separate factual assertions about the everyday world (and if they were, there’d be no need to mark them off as a separate kind of understanding).
Time is (or can be thought of as) just a set of coordinates; what could be described as “you DID live, in the past, but are not alive” could also be described as “you LIVE between thisdate and thatdate”. It may be less useful for everyday living but it is more useful for other types of understanding. Trying to condense it into something it is not — such as an assertion that dead people are still alive after they are dead in the first sense of live — is of no benefit to anyone.
You aren’t Dr. Manhattan by any chance, are you?
Meh, there are a lot of people in this world who believe in reincarnation as result of their religious indoctrination. It’s certainly not going to pass the scientific sniff test, but it’s no more ridiculous than the Abrahamic faiths, and as a general rule the folks who believe in karma/reincarnation tend to be a lot less dangerous and violent. I don’t try and foist my beliefs, or lack thereof, onto others.
Not at the moment, no 
**How to counter “energy can’t be destroyed.” **
Your friend is talking about the first law of thermodynamics, the part about conservation of energy.
Refer her to the second law of thermodynamics, particularly the part about entropy. Entropy can be described as the amount of disorder within a system. Entropy within a system is always increasing. The entropy of the universe is always increasing. Even though the amount of energy may stay the same, the amount of disorder of the energy is increasing.
Being dead involves a high degree of personal entropy. Whatever energy that existed within that system is now highly disordered and will not re-order itself into a useful form.
Is it impossible to destroy matter? I am under the impression that matter is a form of energy and can be converted into other forms of energy. The whole e=mc squared thing. Correct me if I’m wrong.
Matter and energy are interchangable, but you cannot create or destroy either, only convert one into the other.
Exactly. Energy cannot be destroyed, but it damned well can be, and is, converted into other forms of energy all the time.
I agree with the posts suggesting that it’s actually complex organization that makes us human – and organization is fragile! But even if there was a “life energy,” it would almost certainly be constantly getting converted into other forms of energy, dissipating like radiated heat or random Brownian motion, for example.
Or it is going to deliciously reorder usefully in the service of mold, small insects, worms, and daffodils. I expect to be ‘reincarnated’ in the form of 23,000 small worms.