Topological Toyz

Another distinction for Oakland: It's home to the man who makes the nerdiest Christmas gift in America.

Says who? The uber-nerd himself, Nate Silver, the guy who crunches the numbers and makes those uncannily accurate sports and election predictions.

On Black Friday Silver released his FiveThirtyEight 2014 Holiday Gift Guide. And right at the top, with a perfect "Nerd Factor" of 10 out of 10, is a Klein Bottle made by Cliff Stoll, owner and sole proprietor of the Acme Klein Bottle Company, which he runs from the kitchen of his home in North Oakland.

So what's a Klein Bottle? Well, remember your geometry class in high school, when you took a strip of paper, gave it a half-twist, and taped the ends together?

The result was a loop with only one side, one edge, and other properties that math geeks love. It's called a Möbius Loop after August Möbius, the 19th-Century mathematician who invented it.

In 1882 another mathematician named Felix Klein imagined what would happen if you glued two Möbius Loops together: You'd have a bottle with only one side. Its inside would be its outside, and vice versa.

The only problem with a Klein Bottle is that to properly see it you need to live in four dimensions, and we only live in three.

"But you can represent it in three dimensions," says Stoll, "just as a photograph is a two-dimensional representation of something that exists in three dimensions."

Acme Klein Bottles come in all sizes and prices, from the 3 1/2-inch "Baby" bottle, which sells for $35, up to a 3 1/2-foot behemoth that’ll set you back six grand.

You can also buy Klein swag, including a Klein hat and matching Möbius scarf. To get a Klein Bottle for that special geek in your life, visit kleinbottle.com.

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Finally, do you know a senior – say, 55 or older – who is going to be home alone on Christmas?

Senior Center Without Walls is in between its regular sessions right now, but they're bridging the gap by offering special telephone group chats over the holiday season and beyond to keep everyone's spirits merry and bright. All you have to do is call up and join in. Among the offerings:

December 19: Laughing Through The Holidays.

December 21: Holiday Caroling.

December 25: Winter Holiday Celebration.

January 2: Building Friendships.

January 9: Talent Show

January 16: Eating Healthy on A Budget

January 19: A celebration of Martin Luther King Jr. Day with Dr. King's lifelong friend, Dr. Jewell Taylor Gibbs.

SCWW will also offer weekly conversations about Bible study, Improvisation, birdwatching and trivia, as well as online chats about art appreciation and the great American songbook.

Then, on January 26, the regular Winter/Spring session, offering dozens of conversations each week on subjects ranging from the silly to the sublime, will start up. I'll let you know more details when the time draws closer.

In the meantime, you can sign up for any of the holiday break telephone conversations by calling 510-444-5974 or toll-free at 1-877-797-7299.

This time of year can be lonely for isolated older people. If you know someone who might be in this situation, please let them know about this wonderful service. And please remind them that it's 100 percent free.