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Have you ever struggle to do a simple math/physics problem correctly for a long time JUST because of a ridiculous oversight you repeatedly made?

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WannabeNewton
Haha in fact yes. When I was learning topology there was a problem at the end of the chapter on connectedness and compactness which asked to show that if ##X## is a topological space and ##CX = (X \times I)/(X \times \{0\})## is the cone on ##X## then ##CX## is locally connected iff X is connected and locally path connected iff X is locally path connected. I was wracking my head over the problem for days on end and it was driving me quite insane but eventually,thanks to micromass, the solution was found and it turned out to be embarrassingly trivial because I had completely forgotten about fibers and saturated subsets associated with quotient maps, which in retrospect is shameful because they are very important when dealing with properties of quotient spaces.

Another time, I was trying to show that Maxwell's equations in curved space-time implied local charge conservation ##\nabla^{a}j_{a} = 0## but for some reason I kept running into dead ends. It turned out I kept on making the mistake of saying 2 - 2 = 4 lmfao

reenmachine
Gold Member
I lost count of how many times I did it on this very site in the last 2 months :rofl:

MarneMath
Another time, I was trying to show that Maxwell's equations in curved space-time implied local charge conservation ##\nabla^{a}j_{a} = 0## but for some reason I kept running into dead ends. It turned out I kept on making the mistake of saying 2 - 2 = 4 lmfao

I make that error a lot. If i'm in a hurry, I will often go "ok so 2 + 2 = 4" in my head but when i'm writing it down, i'll write 4 + 2 = 6. So when I review my work, I don't see an error because of course 4 + 2 = 6 -_-.

WannabeNewton
I make that error a lot. If i'm in a hurry, I will often go "ok so 2 + 2 = 4" in my head but when i'm writing it down, i'll write 4 + 2 = 6. So when I review my work, I don't see an error because of course 4 + 2 = 6 -_-.
It's funny how the little mistakes are the ones that screw you over xP I blame the media!

jtbell
Mentor
Once during a derivation in a lecture, I set up an integral on the board, then proceeded to take the derivative. A few steps later, one of the students finally got around to correcting me.

hotvette
Homework Helper
Once, in a graduate level partial differential equations class in a large lecture hall, I spaced for a second and missed a step of a derivation. When I interrupted the professor (via microphone) to ask how he'd done the previous step, he replied with a snide comment about me not knowing how to solve two equations with two unknowns. For the next several weeks I was chided by other students about the incident. People can be rather mean. Of course, I never opened my mouth during class the rest of the semester.

Borek
Mentor
I did many mistakes, but the one I remember was made by a friend of mine back in seventies - after solving some kind of a problem correctly he tried to rearrange the final answer and he canceled $\frac 2 2 = 0$. It became proverbial in our group.

Evo
Mentor

View attachment 58796
I hope that's really your daughter because that's so cute.

trollcast
Gold Member
From last nights revision

##\displaystyle x + x = x^2 ##

and

##\displaystyle e^0 = 0##

Although theres probably been worse than that before.

From last nights revision

##\displaystyle x + x = x^2 ##

and

##\displaystyle e^0 = 0##

Although theres probably been worse than that before.

You didn't really do that, did you?

$e^{i\pi}-1=0$

trollcast
Gold Member
You didn't really do that, did you?

Well not like that but in the middle of a solution I wrote both of those down and then wondered why my answer didn't match the mark scheme

AlephZero
Homework Helper
Back in the days when debugging computer programs meant doing hexadecimal mental arithmetic, I sometimes got brain-fade with ordinary decimal arithmetic - e.g. mistakes like 5 times 4 = 32 (because 32 = 0x20).

collinsmark
Homework Helper
Gold Member
From last nights revision

##\displaystyle x + x = x^2 ##

and

##\displaystyle e^0 = 0##

Although theres probably been worse than that before.

You didn't really do that, did you?

I think the second one is a pretty common mistake. I haven't done that one in awhile, but I have done it before. For example, consider:
$$\int_0^a e^x \ dx.$$
Many students would mistakenly evaluate that to be
$$\int_0^a e^x \ dx = e^a,$$
which of course is not correct.

This happens to me so often that it's not funny (or is it?). I tend to do long stretches of study which sometimes make me feel like a zombie. I think my worst one was accidentally doing commas instead of plus signs when calculating a dot product. In my defense, the next step was correct as I'd continued on assuming that I'd written '+'s...

I'm only in High School, but I make simple arithmetic mistakes all the time.

mathwonk
Homework Helper
2020 Award
This is sort of mathematical - I once complained to a grocery store clerk that all the yogurt was outdated, because I forgot what month it really was. He got a kick out of that. I always try to avoid him since then.

I've got it. Once I asked a question of a Fields medalist about his specialty and he began to write briefly on a piece of paper, then stopped without a word. Since I could not see where he was going with it, I thought he was stumped and said "That's ok, I didn't really need it." When he looked at me oddly, but still without a word, I asked if I could have the paper. An hour later in my office, after he had gone home, I realized that what he wrote had completely solved my problem. It took me 20 years to mention it again and thank him.

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Did the clerk know you have a degree in math? That would make it more embarrassing.

Going back almost 8 years to my days in high school, I was absolutely terrible at maths as I didn't apply myself at all over the 5 years I was there. In fact, I don't remember learning anything at all besides basic arithmetic in primary school. Come my GCSE maths exams, I was practically reading hieroglyphs and needless to say, I flunked them.

It wasn't until a few years later during job interviews that I finally realized how much of an embarrassment that huge F looked on my CV. Around the same time, I took a big interest in astronomy, maths and physics, so I felt compelled to change it. I still cringe a little when I think back on it.

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It wasn't until a few years later during job interviews that I finally realized how much of an embarrassment that huge F looked on my CV. Around the same time, I took a big interest in astronomy, maths and physics, so I felt compelled to change it. I still cringe a little when I think back on it.

Sounds like you actually did something about it, what was it?

Anyway, I constantly make silly mistakes, like recently I had to sub t= -9 (t did not stand for time) into an equation, and I kept going wrong until I saw the equation had -t in it, and I never changed the sign of t = -9 . I do that kind of thing frequently.