VDFs might enable more constant block times, for instance by having a two-step PoW:

1. Use a VDF that takes say 9 minutes to resolve (VDF being subject to difficulty adjustments similar to the as-is). As per the property of VDFs, miners are able show proof of work.

2. Use current PoW mechanism with lower difficulty so finding a block takes 1 minute on average, again subject to as-is difficulty adjustments.

As a result, variation in block times will be greatly reduced.

Zac


On Tue, 18 May 2021 at 09:07, ZmnSCPxj via bitcoin-dev <bitcoin-dev@lists.linuxfoundation.org> wrote:
Good morning Erik,

> Verifiable Delay Functions involve active participation of a single
> verifier. Without this a VDF decays into a proof-of-work (multiple
> verifiers === parallelism).
>
> The verifier, in this case is "the bitcoin network" taken as a whole.
> I think it is reasonable to consider that some difficult-to-game
> property of the last N blocks (like the hash of the last 100
> block-id's or whatever), could be the verification input.
>
> The VDF gets calculated by every eligible proof-of-burn miner, and
> then this is used to prevent a timing issue.
>
> Seems reasonable to me, but I haven't looked too far into the
> requirements of VDF's
>
> nice summary for anyone who is interested:
> https://medium.com/@djrtwo/vdfs-are-not-proof-of-work-91ba3bec2bf4
>
> While VDF's almost always lead to a "cpu-speed monopoly", this would
> only be helpful for block latency in a proof-of-burn chain. Block
> height would be calculated by eligible-miner-burned-coins, so the
> monopoly could be easily avoided.

Interesting link.

However, I would like to point out that the *real* reason that PoW consumes lots of power is ***NOT***:

* Proof-of-work is parallelizable, so it allows miners consume more energy (by buying more grinders) in order to get more blocks than their competitors.

The *real* reason is:

* Proof-of-work allows miners to consume more energy in order to get more blocks than their competitors.

VDFs attempt to sidestep that by removing parallelism.
However, there are ways to increase *sequential* speed, such as:

* Overclocking.
  * This shortens lifetime, so you can spend more energy (on building new miners) in order to get more blocks than your competitors.
* Lower temperatures.
  * This requires refrigeration/cooling, so you can spend more energy (on the refrigeration process) in order to get more blocks than your competitors.

I am certain people with gaming rigs can point out more ways to improve sequential speed, as necessary to get more frames per second.

Given the above, I think VDFs will still fail at their intended task.
Speed, yo.

Thus, VDFs do not serve as a sufficient deterrent away from ever-increasing energy consumption --- it just moves the energy consumption increase away from the obvious (parallelism) to the obscure-if-you-have-no-gamer-buds.

You humans just need to get up to Kardashev 1.0, stat.

Regards,
ZmnSCPxj
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