<p>After perusing Satoshi Nakamoto's original paper and <a href="https://blog.bitmex.com/bitcoins-block-timestamp-protection-rules/" rel="nofollow noreferrer">this</a> web site, it turns out the only reason time stamps even matter is for implementing what Nakamoto calls the &quot;moving average targeting an average number of blocks per hour&quot; such that if blocks &quot;are generated too fast, the [proof-of-work] difficulty increases.&quot;  According to the linked web article, the implementation also took potentially falsified time stamps into account, such that there is a 90-minute &quot;maximum allowed gap between the time provided by the nodes and the local system clock&quot; of the node trying to submit a new block.</p>

CC BY-SA 4.0
2021-08-31T20:17:10.947Z
2021-08-31T20:17:10.947Z
tdMJN6B2JtUe
<p>Bitcoin needs approximately sundial time accuracy to operate. Computers have their own free running clocks which provide more than enough accuracy in the absence of other references, and NTP sources which are terrestrial rather than GPS based.</p>
<p><code>nLockTime</code> and other internal tools are not based on local clocks, as there’s absolutely no guarantee that anybody in the network actually has an accurate one.</p>
<p>A situation in which time sync from GPS, GNSS, Baidu and Galileo were all unavailable would be rather apocalyptic anyway and would transcend the availability of Bitcoin.</p>

CC BY-SA 4.0
2021-08-26T18:09:22.187Z
thank you for guiding me to the NTP information.  I had no idea what that stood for until today! https://www.ionos.com/digitalguide/server/know-how/network-time-protocol-ntp/
tdMJN6B2JtUe
CC BY-SA 4.0
2021-08-26T18:10:52.257Z
I have heard that the modern financial system, including such simple things as an ATM withdrawal, relies on GPS timing.  I wanted to make sure Bitcoin is not just as vulnerable: https://qz.com/1106064/the-entire-global-financial-system-depends-on-gps-and-its-shockingly-vulnerable-to-attack/
tdMJN6B2JtUe
CC BY-SA 4.0
2021-08-31T17:33:54.520Z
@user24925 I just skimmed over S. Nakamoto's whitepaper on $BTC and could not see any specific reference to the level of timing accuracy required.  Do you have a reference?
tdMJN6B2JtUe
CC BY-SA 4.0
2021-08-31T18:12:27.950Z
The white paper is really an overview of the system, most of the things aren’t really spelled out as such. I don’t know of a reference for how timing works.
Claris
CC BY-SA 4.0
2021-08-23T16:14:42.373Z
2021-08-23T16:14:42.373Z
Claris
<p>According to <a href="https://www.gps.gov/applications/timing/" rel="nofollow noreferrer">this</a> web site, the timing from a system like GPS is essential to &quot;financial networks [which] rely on precision timing for synchronization and operational efficiency.&quot;  Is the Bitcoin network one of those?</p>

CC BY-SA 4.0
2021-08-23T16:04:20.020Z
For example, does the "lock time" function rely on precise timing? https://coinguides.org/bitcoin-lock-time/
tdMJN6B2JtUe
CC BY-SA 4.0
2021-08-23T16:07:53.437Z
Also what about knowing the accuracy of blockchain timestamps?  Ref this answer: https://bitcoin.stackexchange.com/a/107019/120379
tdMJN6B2JtUe
<currencies><timestamp><p2p><hash-time-locked-contract><time>
What would happen to Bitcoin if GPS/Galileo timing ceased to be available?
tdMJN6B2JtUe
# What would happen to Bitcoin if GPS/Galileo timing ceased to be available?

(Asked by: username_0 on 2021-08-23)

According to [this](https://www.gps.gov/applications/timing/) web site, the timing from a system like GPS is essential to "financial networks [which] rely on precision timing for synchronization and operational efficiency." Is the Bitcoin network one of those?

**Tags:** currencies, timestamp, p2p, hash-time-locked-contract, time

> **Comments:**
> **username_0**: For example, does the "lock time" function rely on precise timing? https://coinguides.org/bitcoin-lock-time/  
> **username_0**: Also what about knowing the accuracy of blockchain timestamps?  Ref this answer: https://bitcoin.stackexchange.com/a/107019/120379  

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## 2 answers

### Answer by username_0 on 2021-08-31. Score: 0 | Accepted answer

After perusing Satoshi Nakamoto's original paper and [this](https://blog.bitmex.com/bitcoins-block-timestamp-protection-rules/) web site, it turns out the only reason time stamps even matter is for implementing what Nakamoto calls the "moving average targeting an average number of blocks per hour" such that if blocks "are generated too fast, the [proof-of-work] difficulty increases." According to the linked web article, the implementation also took potentially falsified time stamps into account, such that there is a 90-minute "maximum allowed gap between the time provided by the nodes and the local system clock" of the node trying to submit a new block.


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### Answer by username_1 on 2021-08-23. Score: 4

Bitcoin needs approximately sundial time accuracy to operate. Computers have their own free running clocks which provide more than enough accuracy in the absence of other references, and NTP sources which are terrestrial rather than GPS based.

`nLockTime` and other internal tools are not based on local clocks, as there’s absolutely no guarantee that anybody in the network actually has an accurate one.

A situation in which time sync from GPS, GNSS, Baidu and Galileo were all unavailable would be rather apocalyptic anyway and would transcend the availability of Bitcoin.

> **Comments:**
> **username_0**: thank you for guiding me to the NTP information.  I had no idea what that stood for until today! https://www.ionos.com/digitalguide/server/know-how/network-time-protocol-ntp/  
> **username_0**: I have heard that the modern financial system, including such simple things as an ATM withdrawal, relies on GPS timing.  I wanted to make sure Bitcoin is not just as vulnerable: https://qz.com/1106064/the-entire-global-financial-system-depends-on-gps-and-its-shockingly-vulnerable-to-attack/  
> **username_0**: @user24925 I just skimmed over S. Nakamoto's whitepaper on $BTC and could not see any specific reference to the level of timing accuracy required.  Do you have a reference?  
> **username_1**: The white paper is really an overview of the system, most of the things aren’t really spelled out as such. I don’t know of a reference for how timing works.  

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