Grad school is totally owning me this week. The second year PhD students all give a big research presentation to the department in the fall that describes what they achieved this summer, and my presentation is this Friday. Our presentations always make us frantic, but it’s extra crazy this week. Today and tomorrow is our 10th annual departmental symposium, so it’s two full days of talks from superstar scientists. Oh, and Svante Paabo (the guy whose group is behind the Neanderthal genome) decided to publish a paper on Thursday related to my work, and that has given me 1988472 new analyses to run. Thanks, Svante. Oh well, at least he didn’t totally scoop me.
Unfortunately this means I’ve been neglecting my blog. You know, for my real job. Sorry guys! Consider this an open thread to talk about whatever or plug your own stuff. The default of the efficacy of machine gun arms on dinosaurs is a good fall back if you run out of things to talk about.
Best of luck. Mine is next month.
Other science news from Eric Hovind this week….It’s impossible for a couple of reasons for an asteroid to have killed the dinosaurs, because the asteroid, they say, was millions of years ago. The earth isn’t millions of years old. And second, they’ve lived with man, as is very very evident. (See The Flintstones)
As much as I hate plugging my own stuff on someone else’s blog, you gave me permission!
If you live in North Texas and don’t know about Ricky Franklin then come take a look:
http://www.rail-bender.com/2011/10/gaming-loopholes.html
He’s found himself what I consider to be a warm and cozy loophole that he’s exploiting with the Byron Nelson High School. Lying for Jesus is starting to get more creative by the day.
A filler post without kitten photos? Noooooo!
Good luck on the presentation!
Erk… self… plugging… irresistible…
I would really appreciate some free-thought feedback for the new blog, linked to in my name, hoorayreality.com
Being a grad student, I am constantly amazed at how much you accomplish re: blogging etc.
This was on my brain today because I’m reading through Shermer’s book The Believing Brain, and “open thread” is just another phrase for “self-indulgent story sharing,” right?
I had a recurring lucid dream some two years ago where I’d “wake up” in my bed in my room. Usually I’d walk outside and start flying, because flying in lucid dreams is totally awesome and that’s what you should do in lucid dreams. But then I idly wondered, what if I’m not just dreaming? What if I’m projecting my soul and am actually interacting with the real world? I decided to test this.
I took a deck of cards, shuffled it, and tossed one face down on my dresser. The idea was to look at it in the dream, see what card it was, and then check to see if it’s the same card in reality, doing this several times just in case I got lucky the first time. I expected to see some random card in the dream and then to find a totally different card in reality. What happened instead, when I found myself dreaming and remembered to check the card for the first time, is that I was transported to the ocean or something. Basically I didn’t get to see what the card was, and this was the case everytime I checked the card. The dream would always conspire so that I never got to view the card.
I was cognizant this was happening the last time I tried to check the card. Thinking “this time I WILL see what the card is,” I flip it, concentrate not to have the dream shift on me, and what I see is a TOTALLY BLANK WHITE CARD.
I gave up after that. Turns out I’m not psychic after all.
There’s nothing wrong with plugging yourself, but please do it in private. ;P
End the Military’s Discrimination against Non-Religious Service Members
One of the Military Relligious Freedom Foundation’s clients, a sergeant in the Army, has started a petition on WhiteHouse.gov to “End the Military’s Discrimination against Non-Religious Service Members.” According to WhiteHouse.gov, 5,000 signatures within 30 days is supposed to get you a response from the White House. The petition, started on October 1 by SGT Dustin Chalker, currently has 3,038 signatures, so it needs 1,962 more by October 31.
https://wwws.whitehouse.gov/petitions/%21/petition/end-military%E2%80%99s-discrimination-against-non-religious-service-members/jcfr6fWt
For those of you in Seattle, you’re invited to join the Seattle Atheists for Post-Rapture Extreme Bowling this Saturday at 8:30pm at AMF Imperial Lanes. Capacity has been reached for the Left Behind screening earlier that evening but we have plenty of space for the bowling after party.
http://www.facebook.com/#!/event.php?eid=296638163682492
ZOMG you have a blog?!!?!
Also, this.
If a, x, and y are vectors, then a.x = a.y does NOT imply that x = y. This is because a.x (a dot x – dot product of a and x) equals the magnitude of a times the magnitude of x times the cosine of the angle between a and x, and so forth. |a||x|cos@(ax) = |a||y|cos@(ay) if:
1. x=y
2. |x|=|y| and @ay=@ax but in a different direction (for instance, if a is the x axis, y is angle @ above it, and vector x is angle @ below it)
3. If |x| = cos@ay and vice versa (IE, if @ay is pi/3 and |x| is Sqrt(3)/2
4. If x is perpendicular to a and y is the zero vector, or vice versa.
So, this does not imply that x and y are equal in magnitude and direction, which is what x=y would mean.
(You could say |x| = |y| and x and y are the same angles from the +x, +y, and +z axes…but if you’re me, you’re in not just a math class, but a “MATH ###” class and the professor’s MPD* will result in points being deducted unless you provide an explicit proof that if two vectors have the same direction, they are the same angle from each of the coordinate axes.)
*Mathematician Personality Disorder. Because the willingness to adopt and enforce conventions that can have the effect of punishing students for displaying insight into the subject matter can’t really be called anything less.
Having passed Algebra II by the kindness of my teacher my senior year in high school, and having majored in one of the most useless fields known to man (music performance), I will simply sit back in awe, wide-eyed at this strange language of yours that you call “math”. :D
Warms my heart to know you haven’t forgotten the discussion of whether machine guns and dinosaurs were contemporary based on the principal of things being awesome.
Implementation of the dinosaurs/machine guns pairing is important though. Terra Nova is an example of what can happen when it’s not done well.
Yesterday I was shocked to see this status update on one of my friends’ Fb wall (and all that comments that supported it):
“I’m watching a video about the brain and I’m sorry,but it makes evolution seem absolutely ridiculous! That all the complicated structure just happened by genetic mistakes and chance? I mean, what the heck people? Seriously?”
Seriously? Because a crazy, moody master puppeteer, for whose existence there’s no scientific evidence, makes more sense?!
http://www.meetup.com/seattle-atheists/events/37853262/
Whenever someone says, “not by chance” my mantra is always, “Natural selection is selective. It’s the opposite of chance.”
What are people’s thoughts on the disparity between environmental awareness (knowing about problems like global warming) and environmental action (actually taking action on problems like global warming).
What are the reasons that folks who know about these things and are worried about them don’t actually ACT on that knowledge and concern?
How do you overcome those barriers?
Is it too much to ask for fricking T-Rex’s with fricking Mini-guns on their heads??? Really people, throw me a bone here.
Steve
I decided to use this platform as Jen suggests..
Please sign this petition before October 22nd. If it reaches 25,000 signatures, the government will issue an official response. Only a few thousand more signatures are required.
Edit the Pledge of Allegiance to remove the phrase Under God
https://wwws.whitehouse.gov/petitions/!/petition/edit-pledge-allegiance-remove-phrase-under-god/v5J2fC6z
http://www.myconfinedspace.com/wp-content/uploads/2011/06/space-t-rex-with-gatling-gun-arms-700×394.jpg
That’s the best I could find…
Oh you cruel cruel tease. All I get is a 403 Permissions Exception when I try to follow the link. Just think, I trip on an unscooped dino-dropping in the parking lot tonight (they are notoriously slick) and shuffle off this mortal coil. My last act will be to regret having never seen a t-rex with a gatling gun.
Steve
Who wonders if he laid on the guilt a bit TOO thick
If a, x, and y are vectors, then a.x = a.y does NOT imply that x = y.
Since you haven’t quantified a, one wouldn’t expect a.x = a.y to imply much of anything (you haven’t ruled out a = 0).
With a stronger antecedent, the implication follows:
(for all a)(a.x = a.y) implies (x = y)
One of my profs, back in the sixties, used to use this acronym: ELFS.
Err, no, because of the things I posted immediately following.
Not TOO thick, but if it had been dino droppings with asparagus scent, it might have been.
Lemme try again – this is the “image link”.
http://www.myconfinedspace.com/wp-content/uploads/2011/06/space-t-rex-with-gatling-gun-arms-700×394.jpg
Interesting book review anyone?:
Been reading this book, “The Sociopath Next Door”, by Martha Stout. I got it on Kobo books for 10 bucks.
Chilling. ~4% (!) of the population are sociopaths, and only a small percentage are locked up because they are killers. The rest of them wreak havoc with the people around them, who are left bewildered and damaged. It is a mental disorder where the person with it suffers no direct ill-effects, but instead affects everyone else they come into contact with. Has no known cure.
If you’ve ever come across someone who seems to be malicious to you or others, and/or does anything to get ahead or overtly or covertly cut you or other people down, reading this book could provide some insight and possible defense against them. In the movie, “Bad Teacher”, Cameron Diaz (IMHO) portrays a classic example of a sociopath, although that label is not used in the movie.
The author takes a very considered, methodical, and scientific approach to the topic.
(No, not a shareholder of Kobo, and don’t know or have anything to do with the author.)
No — you missed the point of the quantification.
If for EVERY a, = , then x = y. Proof: pick a basis e_j. Then we have for each j, x_j = = = y_j, so x = sum_j(x_je_j) = sum_j(y_je_j) implies that x = y.
(Note that if we have equality on a basis, I have equality on all vectors by linearity.)
However, if you merely know there exists SOME a such that = , then for the reasons you outlined you cannot conclude x = y. (In fact, we know of an a that works for every x, y: = for ALL x and y.)
The “(for every a) = implies x = y” is important in establishing that, for finite-dimensional vector spaces, a choice of inner product is equivalent to a choice of isomorphism between a vector space and its dual.
WHY IS THIS STUPID?
Anywhere you don’t see anything, you should see (-,-) or -.-. I tried to use brackets for inner product notation and that horribly failed.
I tried to use brackets for inner product notation and that horribly failed.
You mean like <a,x> = <a,y> ? :-)
You need to use < and >.
(The above looks ok in Preview—here’s hoping…)
If 10,000 monkeys each operate a computer with mathcad installed, will they accidentally solve the three-body problem ?
What’s wrong with just drawing straws?
There are other ways the that magnitude of one vector, times the magnitude of another vector, times the cosine of the angle between them, can equal the magnitude of the first vector, times the magnitude of a third vector, times the cosine of the angle between *them*, than the second and third vectors being equal in magnitude and direction. I described three of them. >.>
There are other ways the that magnitude of one vector …
Hence my original comment that the antecedent in your comment that began this thread wouldn’t lead one to expect that a.x = a.y implied much of anything. It might in the special case where x is known to be a scalar multiple of y, but otherwise one can find an a such that a.x does equal a.y even though x ‡ y. I haven’t noticed anyone in this thread disagreeing with you on that.
On the other hand, if it can be shown for a particular x and a particular y that for every possible a, a.x = a.y, then necessarily x = y. See for example Neal’s comments above.
Hi, testing new comment system.
Re: Neanderthal genome. Have you read Robert T. Sawyer’s sf trilogy “Neanderthal Parallax”? The books are titled “Hominids”, “Humans” and “Hybrids”. It’s a very entertaining biology-related sf story, plus the leading hero is a female geneticist:)
(RAPE TRIGGER WARNING for one early scene. The story is feminist and progressive in tone, though with some minor cliches on gender, sex and race. The science is relatively good.)
Since Jen has given explicit instructions to pimp our wares, I thought I’d mention my Skeptical Kitteh and Science Kitteh t-shirts, which I hope might appeal to the Blag Hag readership:
Skeptical Kitteh is Skeptical
and
Science Kitteh is reviewing your latest paper
I was very lucky to have these featured by Jerry Coyne on Why Evolution is True, since Jerry is such a big fan of all things feline. I have others planned, as well as more diverse science, atheism and skepticism ideas in the works.
Thanks in advance to anyone who takes a look.
Alright, enough of this bad math, you both fail at notation, and discussion.
Additionally
let a = [1,1], x = [1,0] and y = [0,1]
a dot x = [1,1] dot [1,0] = 1
a dot y = [1,1] dot [0,1] = 1
this is a non-trivial example of how dot products do not follow the cancellation law.
indicates complex vector multiplication according to dirac rules. [a,b] is element a and b of a 1 by 2 vector.
Yes, watching this did make me cry just a little.
< and > indicates …
So I fail at html too.
Um. Dude. The only bad math is Azkyroth’s, and it’s only bad because he’s being vague. Ted and I have been pointing out the difference between the following two propositions:
[ (FOR ALL a) (a,x) = (a,y) ] => [ x = y ]
[ (EXISTS a) (a,x) = (a,y) ] => [ x = y ]
As I proved, the former is true.* As you and Azkyroth proved, the latter is not true.
* Here’s the proof again because I think this notation will not fuck up the formatting.
Pick a basis e_j. Then by hypothesis for each j (e_j,x) = (e_j,y). By projection, the jth components of x and y are x_j = (e_j,x) and y_j = (e_j,y). Therefore, for all j we’ve x_j = y_j. This gives that x = y.
Note that [ (EXISTS basis {e_j}) (e_j,x) = (e_j,y) ] suffices to prove the assertion. This is not a weaker hypothesis because we can recover [ (FOR ALL a) (a,x) = (a,y) ] by the linearity of the inner product.
Not as bad as me :)
Okay, open thread eh?
Mentioned earlier on this blog was something related to OK Cupid. As I am now broken up with my boyfriend, I’m going to want to start looking for someone else soon.
Problem, I’m transgender and OK Cupid doesn’t reflect the non-binary genders. I could do one of two possibilities that I figure:
1) Use a feminine nickname and apply as a bisexual female, but put “I am transgender!” in the intro paragraph.
2) Use a feminine nickname, apply as bisexual male, and put “I am transgender!” in the intro paragraph.
The former would make straight males and lesbian females see my profile, the latter would make gay males and straight females see my profile. Bisexual persons would see my profile regardless.
What would be more acceptable, do you think?
Neal You reversed something there.
You did not prove
∀ a if a ⋅ x = a ⋅ y then it must be the case that x == y
since you have not properly qualify your statement
ie it could be worded
if (∀ a ∈ A(a ⋅ x = a ⋅ y and x,y ∈ A)) then it must be the case that x == y
True iff A is a spanning set.
∀ a ∈ A ( if a ⋅ x = a ⋅ y and x,y ∈ A then it must be the case that x == y)
False, case a = [1,1], x = [1,0], y = [0,1]
i.e. only true if A ⊂ ℜ ∪ ℑ (scalar)
HTML does not work well for logical proofs.
What I would do is set up two profiles, one each way that you proposed. Have the same photos and info, if it lets you, but that way all the possible people who would be looking could find you.
Online dating sites really need to get with it and break out of the “M for W, W for M, M for M, W for W” choices. There’s more than four crayons in the box!
I’m not following your criticism. We’re operating in some finite-dimensional vector space V, so the implicit universe of discourse is V. My statement was “if (∀ a ∈ V, a ⋅ x = a ⋅ y) then it must be the case that x == y.” I proved it by noting that (∀ a ∈ V, a ⋅ x = a ⋅ y) iff (∀ a ∈ B, a ⋅ x = a ⋅ y) for some spannning set B, picking a convenient B, and plugging away.