# [ntp:questions] Leap second to be introduced in June

William Unruh unruh at invalid.ca
Mon Jan 19 07:42:23 UTC 2015

```On 2015-01-19, Mike S <mikes at flatsurface.com> wrote:
> On 1/18/2015 6:04 PM, William Unruh wrote:
>
>> UTC always has 86400 seconds per year.
>
> You clearly don't understand how leap seconds work. You're embarrassing
> yourself now. When there's a leap second, there are 86401 SI seconds in

I AM clearly embarrasing myself, since 86400 is the number of seconds
per SAY not year. Slight difference!

Of course there are 86401 seconds in a day including a leap second. But
UTC only sees 86400. It forgets about one of them.

> that year, that's the whole point. You may also be interested to learn
> that a year with the similarly named leap day has 366 days, not the
> usual 365.
>
>> Note UTC differs from TAI by an interger number of seconds, AND that
>> integer changes with the leap second. Ie, it cannot be continuous if TAI
>> is continuous.

I quoted from the document you yourself pointed me at. TAI is
continuous. UTC differes from TAI by and interger number of seconds, and
that integer changes when a leap second occurs. If x is continous x-n
where n changes at some time, is NOT continuous.

>
> Nonsense. When there's a leap second, there's a UTC second numbered
> 23:59:60, ibid. Both UTC and TAI tick forward constantly, with each new
> second uniquely enumerated.
>
>> TAI is monotonic and continuous. UTC thus cannot be.
>
> Now there's a non-sequitur.

```