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How Deep Does the Multiverse Go?

Bob Hearn This is just one person's (202 comments)

personal opinion of the status of the various ideas labelled "multiverse", inappropriately presented as fact. There is certainly not a consensus view that these opinions are correct, as you might mistakenly infer. In fact, "..., with different Big Bangs but very likely with the same fundamental laws and constants" -- it seems to me the weight of professional opinion is actually more on the other side here. His views on Everett's many-worlds interpretation are also counter to those of most people who accept it as valid in the first place. Perhaps most egregiously, if he is going to borrow (linking to) Tegmark's categorization of the different levels of multiverse, he should at least get them right. But he refers to Tegmark's level 1 as level 0, level 2 as level 1, and is a little confused about the distinction between 1 and 2. If you want a much more thorough, and objective, discussion of the various multiverse ideas, you want to read Brian Greene's The Hidden Reality. And of course Tegmark's Our Mathematical Universe is the latest entry into this field, a manifesto of sorts.

about 7 months ago

Data Mining the Web Reveals What Makes Puzzles Hard For Humans

Bob Hearn Re:Sudoku's complexity (44 comments)

Generalized (NxN) sudoku is NP-complete. That's the only sense in which any puzzle is computationally intractable.

This is very fascinating work, but I am skeptical. I design puzzles like this, with computer assistance, and automatically gauging how difficult a puzzle is seems to be basically impossible. The fundamental problem is that the logical structure of a puzzle is not in itself sufficient to gauge difficulty. A huge amount of it is in the presentation, and how the player conceptualizes the puzzle, and how much of the problem can be handled automatically by visual processes. There are puzzles with trivial game trees that I have watched players get totally lost in, because the game tree is not apparent in the puzzle manifestation.

If this research addresses this problem, I will be very impressed.

about 10 months ago

Price of Amazon Prime May Jump To $119 a Year

Bob Hearn Reasonable or not... (298 comments)

I probably wouldn't renew at $119. And without free shipping, I would order less stuff from Amazon. That doesn't sound too good for the shareholders.

about a year ago

Book Review: The Healthy Programmer

Bob Hearn Re:Not a new concept (461 comments)

Not going to get into all the arguments here. Yes, it is more complicated in detail than the simple model Walker lays out. But in practice, *if* you count calories as prescribed, *then* the model is good enough.

I'd like to provide an update here. I read about the Hacker's Diet first on Slashdot, in fall 1999. I followed it, and during 2000 I lost 50 pounds. I've kept it off for 13 years now. A few years later I started running. I've now run 96 marathons and ultramarathons, heading towards my 10th consecutive Boston Marathon, I've broken 3 hours four times, and I've run three 100 milers, including Western States. Couldn't be happier with that part of my life.

The running has been a bigger life change than losing weight. But I couldn't have done it, no way, without losing the weight first. And I have the Hacker's Diet to thank for that.

And yes, running 60-70 miles / week, I *still* have to count calories.

about a year and a half ago

No US College In Top 10 For ACM International Programming Contest 2013

Bob Hearn Re:Could be a good sign... (199 comments)

I would guess that you've never entered one of these competitions. To do well, it is not sufficient to come up with quick and dirty solutions; these will generally fail. You have to be able to find a good algorithm, quickly, and implement it, catching all the edge cases. These are certainly valuable real-world skills.

Disclaimer -- I was on the Rice team that took 3rd in 1986 (before there were any international teams at all).

about a year and a half ago

China's Radical New Space Drive

Bob Hearn It *is* possible to build a reactionless drive... (419 comments)

... sort of. And it is established physics. See Swimming in Spacetime: Motion by Cyclic Changes in Body Shape, Science, 2/27/2003, by Jack Wisdom.

But this mechanism relies on general relativistic effects, and only works in curved spacetime. Momentum conservation is not violated, because while the location of the object changes, its momentum (thus velocity) does not -- it simply cyclicly translates itself through space.

My first thought reading about the EmDrive was that Shaywer had found a way to reproduce this effect using a microwave cavity. But unless I'm mistaken, this does not appear to be the case, and I don't follow the arguments that Shaywer's drive should work.

about 2 years ago

Pi Day Is Coming — But Tau Day Is Better

Bob Hearn Re:Bah. e is better than them all (241 comments)

Then, when somebody wants to argue that twice e is actually a better constant, we can say "2e or not 2e, that is the question."

more than 2 years ago

Looking Back At OS X's Origins

Bob Hearn BeOS (312 comments)

Left out of that history is the branch that almost happened: for quite a while the smart money was that Apple would buy Be, Inc. and use BeOS as the basis for their future OSes. More than a few developers (myself included) based their business models on this happening.

more than 4 years ago

Programming Clojure

Bob Hearn "This fits me perfectly as a Java programmer," (109 comments)

Exactly. That was the big problem I had with the book: it's written for Java programmers. I am intrigued by the language, but I would much prefer a book that treats the language on its own terms.

more than 4 years ago

All the Best Games May Be NP-Hard

Bob Hearn Re:I don't get why... (322 comments)

The reason that fun games tend to be NP-hard (or harder) is that if a game's "physics" supports interesting constructions requiring complex reasoning to solve, then probably that same physics can be used to build computational gadgets, which is how you show hardness of the generalized version. This quality expresses itself even on small, fixed-size board.

more than 4 years ago

All the Best Games May Be NP-Hard

Bob Hearn Re:Just to throw this out there (322 comments)

Ah, it doesn't mean that either. :-)

If a problem is NP-hard, it means it is at least as hard as any other problem that can be solved in polynomial time on a nondeterministic computer.

It is an open question (P=NP) whether this is equivalent to saying that there is no deterministic polynomial-time algorithm.

more than 4 years ago

All the Best Games May Be NP-Hard

Bob Hearn Re:chess and go aren't np-hard, but they are also (322 comments)

Chess and Go are actually EXPTIME-complete, even harder than NP-complete problems and PSPACE-complete problems.

In general, one-player games of bounded length (like Flood-It, or Sudoku) tend to be NP-complete; one-player unbounded games (like sliding-block puzzles, or Sokoban) tend to be PSPACE-complete; two-player bounded-length games (like Hex, or Amazons) also tend to be PSPACE-complete, and two-player unbounded games (like Chess, Checkers, and Go) tend to be EXPTIME-complete.

I can't resist here a plug for my book (with Erik Demaine), Games, Puzzles, and Computation, which discusses all these issues in detail. A theme running throughout the book is the same as the view expressed in this paper: most interesting games and puzzles seem to be as hard as their "natural" complexity class, outlined above.

more than 4 years ago

Alternate Star Trek TOS Pilot Found

Bob Hearn My favorite part of the clip: (134 comments)

"George Takei as Chief Physicist"

Helmsman, swordsman, physicist... the guy can do everything!

more than 5 years ago



Computer Beats Pro at U.S. Go Congress

Bob Hearn Bob Hearn writes  |  more than 6 years ago

Bob Hearn writes "History was made today at the U.S. Go Congress, where the go program MoGo, running on an 800-core supercomputer, beat 8-dan professional go player Myungwan Kim in a 9-stone handicap game. Computers are still a long way from beating the best human players in an even game; nevertheless, today's performance represents a huge stride forward. In the last such high-profile matchup, in 1997, Janice Kim (then 1-dan professional) beat then-champion program Handtalk with a 25-stone handicap. In fact, most of the improvement in the level of computer-go play has happened in just the past few years. Today's top programs, including MoGo, use a Monte Carlo approach: they simulate thousands of random continuations per second from the current position to the end of the game, accumulating statistics in a tree on which moves lead to wins most often. One of the strengths of this approach is that it is highly amenable to parallelization. Thus, today's 800-core incarnation of MoGo is by far the strongest go computer that has yet existed. After the game Myungwan Kim estimated the strength of MoGo as "two or maybe three dan", corresponding to a reasonably strong amateur player. (Professional dan ranks are at a much higher level than amateur dan ranks.) "Congratulations on making history today," game organizer Peter Drake told both Kim and Olivier Teytaud, one of MoGo's programmers, who participated in a brief online chat after the game.

I was in attendance at the match, and most in the audience were shocked at the computer's performance; it was naturally assumed that the computer would be slaughtered, as usual. Go is often seen as the last bastion of human superiority over computers in the domain of board games. But if Moore's law continues to hold up, today's result suggests that the days of human superiority may be numbered."

Link to Original Source

RIP ClarisWorks, 1991-2007

Bob Hearn Bob Hearn writes  |  more than 7 years ago

Bob Hearn writes "With the introduction of iWork '08, which includes the new Numbers spreadsheet, it appears that ClarisWorks, aka AppleWorks, is finally dead. There has been no official cancellation announcement, but AppleWorks no longer shows up under the list of software titles on the online Apple Store, and perhaps more significantly, http://www.apple.com/appleworks now redirects to http://www.apple.com/iwork. Active development on AppleWorks evidently ceased some years ago, but the program continued to be sold. No longer, it seems.

If you are historically inclined, here is a history of the development of ClarisWorks that I wrote four and a half years ago. RIP ClarisWorks, 1991-2007."


Bob Hearn has no journal entries.

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