In the Einstein thread, someone’s image shows Einstein proving 2=1 as follows (I left out some intermediate steps):
a=b
a^2 = ab
a^2 - b^2 = ab - b^2
(a+b)(a-b) = b(a-b)
a+b = b
b+b=b
2b=b
2=1
Reasons:
Assumption
Multiply both sides by a.
Subtract b^2 from both sides.
Factor the above
Divide both sides by common factor (a-b)
Substitute b for a (since a=b)
Combine common terms on both sides
Divide both sides by b
Here’s a question for the math geeks out there (myself among them).
What is the problem with the above proof?
We know 2 does not equal 1, but all the algebra above looks fine.
Or does it …
in the step from 4, on the right side of the equation it says: b(a-b), in order to get to step 5, b(a-b) must be divided by (a-b). This is forbidden and not possible in mathematics, because since a=b it would mean you are dividing something by 0 (zero). Illegal action.
Since I posted the picture, I felt it only proper to forgo responding until others had a chance to do so. Originally, I tried to use E and mc^2 instead of a and b, but it just got out of hand –
E = mc^2
E^2 = E(mc^2)
E^2 - (mc^2)^2 = E(mc^2)- (mc^2)^2
(E + (mc^2)) * (E - (mc^2))= (mc^2) * (E - (mc^2))
((E + (mc^2)) * (E - (mc^2)))/(E - (mc^2))= (mc^2) * (E - (mc^2))/(E - (mc^2))
E + (mc^2) = (mc^2)
(mc^2) + (mc^2) = (mc^2)
2(mc^2) = (mc^2)
(2(mc^2))/(mc^2) = (mc^2)/(mc^2)
2 = 1
The parenthesis were making my head hurt, and it was becoming obvious that this would not fit around his hand, so I went with the classic “a = b”. If there is anyone out there who has more patience for this than I do, you’re welcome to check the work and see if the parens are correct.
I skipped over the other responses to give my answer:
Equations 2 through 4 can only be constructed if a=b, as in equation 1. For any value of a or b, the (a-b) multipliers in equation 4 must be zero. This renders them meaningless as a multiplier (division by zero is undefined), so they cannot be factored out, and equation 5 is therefore invalid.