The Last POWER1 CPU on Mars Is Dead • Hacker News Board

Re: The Last POWER1 CPU on Mars Is Dead

#81

Post by yingw787 » Mon, Feb 25, 2019, 11:14 PM UTC

basicplus2 wrote: post #74

yingw787 wrote: post #5

Might be O/T, but I found it really interesting how they mention "5,352 Martian solar days". Do we humans have plans in the pipeline for a universal time standard we can use wherever we are? Something that is a little more useful than "seconds since UNIX epoch" but something a little less terrestrial than UTC? Or is time going to be based wherever we land or travel (e.g. divide up Mars into time zones upon colonizati…

A system based on SpaceTime with reference to the centre of the universe

I don't know. First we'd have to identify if there is one center of the universe; can we guarantee that the universe expands uniformly? I can't find anything online and I'm not a physicist. If there are multiple centroids of the universe, and they're all moving, we probably can't establish an eternal reference point.

Also I think the confidence interval for instrumentation looking that far ahead would be so big comparative to current/possible local solutions, we're probably better off doing something in the Solar System instead.

One advantage of synchronizing to some reference in the Solar System, and maybe setting clock boosters as floating checkpoints in space, is we will always be able to find our way home :)

Re: The Last POWER1 CPU on Mars Is Dead

#82

Post by yingw787 » Mon, Feb 25, 2019, 11:17 PM UTC

magduf wrote: post #70

make3 wrote: post #16

Earlier quoted context omitted.

must be Terran time, as literally all humans are currently either on Earth or orbiting around Earth, so literally everyone can relate

>as literally all humans are currently either on Earth or orbiting around Earth The fact that this phrase of yours is literally true, and it's already 2019, makes me very sad.

Hey cheer up now, there's no aliens we've found yet to compare to! We go our own pace and do our own thing, and Mister Rogers will always love you, and that's all that matters.

Re: The Last POWER1 CPU on Mars Is Dead

#83

Post by laumars » Mon, Feb 25, 2019, 11:25 PM UTC

JumpCrisscross wrote: post #9

yingw787 wrote: post #5

Might be O/T, but I found it really interesting how they mention "5,352 Martian solar days". Do we humans have plans in the pipeline for a universal time standard we can use wherever we are? Something that is a little more useful than "seconds since UNIX epoch" but something a little less terrestrial than UTC? Or is time going to be based wherever we land or travel (e.g. divide up Mars into time zones upon colonizati…

> Do we humans have plans in the pipeline for a universal time standard we can use wherever we are? This fundamentally cannot exist. Any "universal" system would drift for observers on different planets. Having different times in New York and New Delhi isn't the worst right now; doing a calendar look-up for the time on Mars isn't as neat. But given we won't have real-time communication, it isn't as big of a problem e…

> This fundamentally cannot exist. Any "universal" system would drift for observers on different planets.

I hear this argument a lot for why we cannot have a universal time standard but it's a weird cyclic argument because it suggests the measurement of time has to be constant while acknowledging that time is relative. So why can't we have a measurement that is also relative?

For example it could be n "ticks" where mass and speed is at a predefined value and allow for decimal points to account for people travelling faster (for example). This means people's life expectancy (for example) could not be measured in "ticks" because "ticks" is used for time synchronisation rather than measuring the passage of time and those who are only interested in the passage of time can use local time zones just like we do now with UTC for keeping equipment synchronised but local time zones for scheduling our human lives.

Re: The Last POWER1 CPU on Mars Is Dead

#84

Post by jrhurst » Mon, Feb 25, 2019, 11:30 PM UTC

laumars wrote: post #83

JumpCrisscross wrote: post #9

Earlier quoted context omitted.

> Do we humans have plans in the pipeline for a universal time standard we can use wherever we are? This fundamentally cannot exist. Any "universal" system would drift for observers on different planets. Having different times in New York and New Delhi isn't the worst right now; doing a calendar look-up for the time on Mars isn't as neat. But given we won't have real-time communication, it isn't as big of a problem e…

> This fundamentally cannot exist. Any "universal" system would drift for observers on different planets. I hear this argument a lot for why we cannot have a universal time standard but it's a weird cyclic argument because it suggests the measurement of time has to be constant while acknowledging that time is relative. So why can't we have a measurement that is also relative? For example it could be n "ticks" where m…

Speed relative to what?

Re: The Last POWER1 CPU on Mars Is Dead

#85

Post by Varcht » Mon, Feb 25, 2019, 11:31 PM UTC

AngryData wrote: post #60

DannyB2 wrote: post #40

Earlier quoted context omitted.

According to relativity, you cannot get two different observers to agree on any kind of universal time, or even the order in which two events occurred. Observer A says that event X happened before Y. Observer B says that event Y happened before X. And they're both right from their POV.

Couldn't you just pick a pulsar or something, all agree to take their measurements from X distance from pulsar, and use that as the standard? It would be time + location, making your local time depending on the distance and number of pulses from the 0 starting pointing. As long as you kept account of the number of pulses as you moved through space, you could use that as a standard, and whenever you met up somewhere e…

Pulsar seemed like a good idea but seems it has some difficulties.

Due to their small size, pulsars are relatively weak radio sources. Therefore, the largest radio telescopes in the world are usually needed to observe them. As we have seen, pulsars emit their largest intensity at low radio frequencies around 400 MHz. In particular at such frequencies, however, the pulses suffer from propagation effects when they travel to Earth through the interstellar medium. [0]

[0http://www.jb.man.ac.uk/distance/frontiers/pulsars/section4....

Re: The Last POWER1 CPU on Mars Is Dead

#86

Post by omeid2 » Mon, Feb 25, 2019, 11:34 PM UTC

JumpCrisscross wrote: post #9

yingw787 wrote: post #5

Might be O/T, but I found it really interesting how they mention "5,352 Martian solar days". Do we humans have plans in the pipeline for a universal time standard we can use wherever we are? Something that is a little more useful than "seconds since UNIX epoch" but something a little less terrestrial than UTC? Or is time going to be based wherever we land or travel (e.g. divide up Mars into time zones upon colonizati…

> Do we humans have plans in the pipeline for a universal time standard we can use wherever we are? This fundamentally cannot exist. Any "universal" system would drift for observers on different planets. Having different times in New York and New Delhi isn't the worst right now; doing a calendar look-up for the time on Mars isn't as neat. But given we won't have real-time communication, it isn't as big of a problem e…

> doing a calendar look-up for the time on Mars isn't as neat

This is actually not that a big deal, in many countries, like Afghanistan and Iran, people observe 3 different calendars for different purposes and they all drift from each other! That is, 1st Jan (Georgian) is not always 24th Jaddi/Dey (Afghan/Iranian - Solar) nor 7th of 7th Jumada i-ula (Lunar/Islamic)..

So people use calendars that look like this for each day: https://en.wikipedia.org/wiki/Rumi_calendar#/media/File:1911...

Re: The Last POWER1 CPU on Mars Is Dead

#87

Post by jakeinspace » Mon, Feb 25, 2019, 11:35 PM UTC

oso2k wrote: post #68

gonehome wrote: post #54

Earlier quoted context omitted.

Somewhat comically J.C.R Licklider's first proposal for what became the internet was titled the Intergalactic Computer Network. He later said he did this because when the project is inevitably downsized it would at least cover the earth. Interplanetary internet designs and peering are interesting problems to think about though. https://en.wikipedia.org/wiki/Intergalactic_Computer_Network

There are real, standardized protocols [0] for this sort of thing, now. Early in my career, when I worked at JPL/NASA, I did a bit of work to test these protocols on Linux in a simulated Network of spacecraft. Fun stuff! [0] https://en.wikipedia.org/wiki/CCSDS_File_Delivery_Protocol

What a coincidence, I'm working on the core flight system project right now, which includes an implementation of CCSDS File Delivery Protocol. You might be happy to know that project is still very much alive within NASA (you were probably already aware).

Re: The Last POWER1 CPU on Mars Is Dead

#88

Post by laumars » Mon, Feb 25, 2019, 11:41 PM UTC

jrhurst wrote: post #84

laumars wrote: post #83

Earlier quoted context omitted.

> This fundamentally cannot exist. Any "universal" system would drift for observers on different planets. I hear this argument a lot for why we cannot have a universal time standard but it's a weird cyclic argument because it suggests the measurement of time has to be constant while acknowledging that time is relative. So why can't we have a measurement that is also relative? For example it could be n "ticks" where m…

Speed relative to what?

Fair point, I overlooked that problem. You might get away with using the centre of the galaxy as a point of reference?

To be honest I'm really not qualified to be making these sorts of comments so I'm going to back away from the keyboard and if there's any merit to the idea at all (which there probably isn't) then someone else who understands this stuff better can chime in.

Re: The Last POWER1 CPU on Mars Is Dead

#89

Post by azernik » Mon, Feb 25, 2019, 11:43 PM UTC

dooglius wrote: post #49

mattkrause wrote: post #38

Earlier quoted context omitted.

I think NTP uses some statistical tricks to get better synchronization than you'd expect over slow, laggy internet links. Possibly something like that could work.

If we're talking interstellar travel, we're likely talking about spacecraft undergoing very significant acceleration and velocity. I'm not a physics expert, but from my understanding it seems that a starship would need to have a very accurate idea of its own acceleration vs reference time curve (relative to some reference frame) in order to calibrate its own ticking clock to the reference frame. For NTP, this isn't s…

It doesn't necessarily need a very good model of acceleration - you can probably get by with a) time at which a reference event is defined to have occurred, and b) distance to that event. From that and your locally-experienced acceleration you can (I think?) calculate relative speed and time drift.

Re: The Last POWER1 CPU on Mars Is Dead

#90

Post by saagarjha » Mon, Feb 25, 2019, 11:49 PM UTC

omeid2 wrote: post #86

JumpCrisscross wrote: post #9

Earlier quoted context omitted.

> Do we humans have plans in the pipeline for a universal time standard we can use wherever we are? This fundamentally cannot exist. Any "universal" system would drift for observers on different planets. Having different times in New York and New Delhi isn't the worst right now; doing a calendar look-up for the time on Mars isn't as neat. But given we won't have real-time communication, it isn't as big of a problem e…

> doing a calendar look-up for the time on Mars isn't as neat This is actually not that a big deal, in many countries, like Afghanistan and Iran, people observe 3 different calendars for different purposes and they all drift from each other! That is, 1st Jan (Georgian) is not always 24th Jaddi/Dey (Afghan/Iranian - Solar) nor 7th of 7th Jumada i-ula (Lunar/Islamic).. So people use calendars that look like this for ea…

That only works if days are the same length, no?