undefined | Better HN

0 pointscoder5434y ago0 comments

Would you be so kind as to show how to reverse a hash? A summary is like a hash; it throws away information deemed irrelevant to the task at hand, but it is still related to the input information. So, no, I won't show how to do that, because it's impossible, and I never claimed otherwise.

I just love these "gotcha!" comments that pop up on HN so frequently. I'm having to explain what it means to summarize information.

Hashes aren't useless or meaningless, they just aren't a substitute for the full information if you need the full information. I'm sure that if you're a serious potential customer, you can contact Form Energy and get whatever detailed information from them that you need. Otherwise, you obviously only get the information they choose to disclose publicly.

Your desire for more information doesn't somehow make "100 hour battery" a meaningless statement. When you see the mpg rating of a car, that is a summary that has thrown away detailed test results that could tell you more about the fuel economy of the vehicle under various conditions. EPA testing involves multiple test "cycles" that represent different conditions, but you don't typically get to see the results of each cycle. People still like to see mpg ratings and compare them.

0 comments

specialist4y ago

> I'm having to explain what it means to summarize information.

It is what it is.

FWIW, I use HN as batting practice, to refine my talking points.

A terrific recent example is Scott Galloway advocating breaking up big tech. Observing his message craft over the years is instructive, inspirational. He now says stuff like "oxygenate the market". Brilliant.

Choice of metaphor matters. "The different between the right word and almost right word is the different between lighting and a lightning bug." -- Mark Twain (from memory)

Keep going. You're doing great!

amelius4y ago

I didn't ask for exact values, and never expected them.

But if you say "summary", then I'd expect at least to get some info in the right ballpark. Otherwise it is not a summary, but just some alternative bit of (possibly relevant) information.

Also, a hash is not a right analogy for a summary because typically hashes don't hold any bits of useful information, at least within reasonable computational limits.

Izkata4y ago

That isn't a gotcha comment. If it's a summary, you should be able to compare it to something else, or pick a baseline to reverse it. For example:

* What's the equivalent summary statistic for an iphone battery?

* If it has the same discharge stat as an iphone battery (just picked arbitrarily for calculation purposes), the 100-hour battery's capacity should be calculable.

coder543OP4y ago

The comparison has to be meaningful. This is a term used for grid scale batteries, and the capacity is irrelevant to this number. Lithium ion grid scale batteries are “4 hour batteries”, roughly. Depending on the exact chemistry and configuration, they could be anywhere from 2 hour batteries to 8 hour batteries.

You can compare Form Energy’s 100 hour batteries to traditional lithium ion and see that Form’s batteries are 25x slower. That’s a valuable datapoint, and speaks to a limitation of Form’s batteries.

The time to discharge an iPhone battery at maximum supported output of the battery is entirely irrelevant to iPhones.

j / k navigate · click thread line to collapse