Batteries: Is Cheap Cheap or Inexpensive?

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Dot Physics: Are Expensive Batteries Worth the Extra Cost?

If you have kids, you probably know this already, but lots of stuff needs batteries. Remote control toys, Wii remotes, laser pointers (well, that is for me), flash lights, even Nerf guns. For me, I have found the best place to pick up batteries is at one of these “dollar” stores. Sure the batteries are cheaper, but are they any good? Who knows. Let’s find out.

I go through batteries at a prodigious pace at times, what with photography and geocaching, so I go with NiMH batteries and a charging station (though I also tend to carry a pair of alkaline batteries as an emergency backup). The problem with NiMH batteries is the tendency to discharge when not in use, but hybrid batteries (sometimes labeled “pre-charged”) keep their charge better than the old ones.

Another Leap of Timing Faith

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Wait just a (leap) second

A nice little summary of leap seconds and the current state of affairs. But there’s a comment at the end that I think has dropped a minus sign.

Why not just decouple the two clocks, and let them go their separate ways?
A lot of scientists do in fact feel this way. But it turns out to be really, really complicated to do that. A lot of computer systems (including satellite navigation systems) have software written a while ago, and changing that would be difficult and have unforeseen consequences. Fiddling with that may be dangerous.

Decoupling atomic time from earth rotation time requires no fiddling — you just stop inserting leap seconds into UTC. Clocks generally don’t get their cues from earth rotation, they get them from synchronization to official time, which is atomic time (in the US). It’s the fiddling — the insertion of the leap seconds into the atomic time signals — that contains the potential pitfalls.

Having countries change their official time from GMT (which is mean solar time) to UTC would be technologically trivial. It turns out that in the US this happened just a few years ago; the wording describing our time zones was changed from GMT to UTC in the America Competes Act in 2007. Even though the basis for time had been atomic time anyway, it wasn’t official until then, but nothing really changed (as far as I can tell) when the law took effect.

Status Update

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I’m back from ScienceOnline 2012, which was great, and am now in detox recovery mode. Catching up on things, including sleep — being “up” all day and part of the night, because of all the interesting discussions, is tiring, but it’s a good kind of tired. I expect this will leave me energized in the way I was last year once I get my bearings again. I intend to write up my thoughts on the conference as I did last year. I also have photos to edit and upload from a visit to the JC Raulston Arboretum.

You've Got Some Explaining to Do

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Electric Material in Mantle Could Explain Earth’s Rotation

Well, not really. The electric material could explain some of the small variations in the Earth’s rotation. Not quite the same thing.

Earth’s spin isn’t flawless. Geophysicists have discovered that the time it takes our planet to complete one rotation—the length of a day—fluctuates slightly over the course of months or years. They’ve also noticed extra swing in the predictable wobble of Earth’s axis of rotation, like the swaying of a spinning top. The variations are probably caused by the solid iron inner core, liquid metal outer core, and rocky mantle rotating at slightly different rates. Friction helps bring them into line, and the magnetic field of the outer core can pull on the metal inner core. But to really fit the observations, the core should also exert its magnetic tug on the mantle, says Bruce Buffett, an earth scientist at the University of California, Berkeley, who was not involved in the new study. This means that a layer of the mantle must be able to conduct electricity. But, he says, “the origin of the metallic layer remains an open question.”

What She Said

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why i’m terrified (but excited) about science online 2012

All of the pre-#scio12 chatter has picked up in recent weeks, and now that we’re entering the final countdown, I’m (thankfully) recovered enough from a nasty respiratory infection to tune in again. The problem is that tuning in at all is like a highly addictive drug: I get a taste and I want more. You people are going to make me into a junkie.

I, too have been distracted by an illness (a nasty cold) and am just emerging to deal with all the last-minute details of going to ScienceOnline2012. I’m excited because last year was a lot of fun and this year promises even more. Last year pumped me up, blogging-enthusiasm-wise, and it lasted for a few months. So I’m looking for that same kind of score this year.

Because of my cold I don’t have posts in the queue yet, and I don’t expect to have a lot of free time, so things may go quiet.