How could the “unhackabilty” of quantum Internet justify its cost?

The U.S. Department of Energy (DOE) seems to be very excited about the potential of a quantum Internet:

One of the hallmarks of quantum transmissions is that they are exceedingly difficult to eavesdrop on as information passes between locations. Scientists plan to use that trait to make virtually unhackable networks. Early adopters could include industries such as banking and health services, with applications for national security and aircraft communications. Eventually, the use of quantum networking technology in mobile phones could have broad impacts on the lives of individuals around the world. […] the quantum internet could become a secure communications network and have a profound impact on areas critical to science, industry, and national security.

So quantum transmissions would reveal if they were read in transit before the intended recipient, which would preclude MitM attacks. But so does TLS, and even though MitM attacks against TLS are possible, the vast majority of attacks are conducted not against data in transit, but against data at rest, OS and hardware vulnerabilities, and most commonly (between 80% and 98%, depending on which statistics you look at), via social engineering. I’ve looked at several cybersecurity stats, and the bottom line is that the vast majority of attacks are due to human error.

I’m trying to understand the excitement about the quantum Internet, and the reasons for the investments going into it.

Could quantum-secure transmissions help in any way mitigate the types of cyberattacks we’ve been seeing in the past 10 years, and which are likely to continue? "Early adopters could include industries such as banking" – how much has banking been affected by insecure Internet links (rather than hosts or persons)?

Or does the press release completely gloss over something else – that quantum computers (rather than the quantum Internet) would be able to break current public key crypotography, hence a quantum Internet would be useful to prevent those future attacks? Is that it, and a case of a vague press release, or am I neglecting something else?

In any case, I’m failing to understand how "the use of quantum networking technology in mobile phones could have broad impacts on the lives of individuals around the world". The vast majority of mobile phone users are completely oblivious to the security of their communications, and they wouldn’t behave any differently if they thought their communications were completely secure.

What is a spell slot in-lore, and how does it justify the limits on casting spells?

Spell slots are something that we, as players, expend when we want our spellcasting PCs to cast a spell. It is a resource to limit how many powerful spells we can cast in a day. But for our characters in-game, they don’t exist. So what are they?

The best way I can think of to illustrate my question is via an example involving a Kenku.


I was going to ask the question “Can a (non-spellcaster) Kenku cast a Verbal-component-only spell that they have heard a spellcaster cast via Mimicry?” I knew the answer would be that they can’t, but I was wondering what the in-game justification is for this.

Out-of-game, the answer is that they do not have the Spellcasting (or Pact Magic) class feature, and therefore do not have spell slots to expend to cast the spell, but that just replaced one question with another; what is a spell slot in-game? Knowing the answer to this would justify why the Kenku perfectly mimicking the Verbal component of a spell doesn’t work in-game.


There are other terms we use: HP, AC, XP; these terms do not exist in-game. My PC won’t know what “HP” is. HP has an in-game description, as explained further in this question: What does HP represent?

In short, from the PHB, pg. 196:

Hit points represent a combination of physical and mental durability, the will to live, and luck.

So those are things that my PC might know about and understand; luck, the will to live, etc. They make sense in-game and are something my character could talk about.

What I’ve Looked Up

A Wizard’s Spellcasting class feature (PHB, pg. 114) only describes the mechanics of what a spell slot is to the player (I didn’t check the Spellcasting class feature for all the other classes), and the Spell Slots section (PHB, pg. 201) simply says (regarding flavour):

Manipulating the fabric of magic and channeling its energy into even a simple spell is physically and mentally taxing, and higher-level spells are even more so.

But that doesn’t explain why, say, a Kenku who has learned to mimic a Wizard’s spell’s Verbal components couldn’t cast a spell (without being a spellcaster class themselves; i.e. they have no spell slots).

Sure, it might “tax” them, but surely they’d be able to pull it off at least once that day? Or is it so taxing to even say that specific word or phrase that they wouldn’t actually be able to even finish saying it “without the proper training” (e.g. being a Wizard), and thus cannot “complete” the spell? (NB: This isn’t my question, it’s just included to show my train of thought.)


So what are spell slots in-game? What in-game “thing” do they represent? Is there an in-game justification for why a character who has spell slots can cast a spell in-game, whereas a different character without spell slots could not (even if they can satisfy the spell’s components; i.e. a Kenku perfectly mimicking the Verbal component)?

If the flavour of certain spellcasting classes would influence the answer such that all classes cannot be explained by one explanation (i.e. because Warlocks have Patrons, Sorcerers have “a spark of magic within them”, divine casters have gods or ideals, etc) then this question can just focus on Wizards specifically and what their spell slots mean, since a Wizard’s relationship with magic (i.e. “learning”) is closer to how a Kenku “learns” the Verbal component via mimicry.

Also, I’m not particularly interested in a settings-specific answer, but if a specific setting would influence an answer, let’s assume the Forgotten Realms (as it is the default setting of 5e).

Just to clarify: I don’t think the Kenku should be able to do this (e.g. a level 1 Kenku overhears a high level Wizard cast wish, uh… no), my question is why not from an in-game/lore perspective.

The power level of the Sword of Sharpness doesn’t justify its very rare rating – am I missing something?

After asking this question about the Sword of Sharpness, I was presented with this answer which distinguishes between the two main features of the Sword of Sharpness:

Feature 1 (emphasis mine):

When you attack an object with this magic sword and hit, maximize your weapon damage dice against the target.

Thus feature 1 only applies to attacking an object.

Feature 2 (emphasis mine):

When you attack a creature with this weapon and roll a 20 on the attack roll, that target takes an extra 4d6 slashing damage. Then roll another d20. If you roll a 20, you lop off one of the target’s limbs, with the effect of such loss determined by the GM. If the creature has no limb to sever, you lop off a portion of its body instead.

This 2nd feature applies to attacks against creatures and has a 1/400 chance of lopping off the creature’s limb.

There is also a third feature to the sword:

In addition, you can speak the sword’s command word to cause the blade to shed bright light in a 10- foot radius and dim light for an additional 10 feet. Speaking the command word again or sheathing the sword puts out the light.

My question: if the first feature doesn’t apply to attacks against creatures, then why is the Sword of Sharpness a very rare weapon requiring attunement? Is there something amazing about cutting off a limb that outweighs its low probability of occurring? I am especially curious since there are many benign ways of creating light, meaning that to me the 3rd feature pales in comparison to the first two. But if the first 2 features don’t synergize at all, then why is this item so rare (and consequently expensive)?

I ask since compared to other magical items of similar rarity, the sword, should it not synergize, seems a bit underpowered. Consider for example the Flame Tongue:

You can use a bonus action to speak this magic sword’s command word, causing flames to erupt from the blade. These flames shed bright light in a 40-foot radius and dim light for an additional 40 feet. While the sword is ablaze, it deals an extra 2d6 fire damage to any target it hits. The flames last until you use a bonus action to speak the command word again or until you drop or sheathe the sword.

Having a constant 2d6 fire damage seems, from a damage perspective, to be greater than the 1/20 chance of dealing 4d6 slashing damage. This sword also produces more light than the Sword of Sharpness.

A similar concern exists with the Scimitar of Speed:

You gain a +2 bonus to attack and damage rolls made with this magic weapon. In addition, you can make one attack with it as a bonus action on each of your turns.

Having an extra attack to use on my bonus action and consistently having +2 to hit and damage also seems to be a stronger option than the 1/20 chance of dealing 4d6 extra slashing damage or the 1/400 chance of lopping off a limb.

Assuming the above to be true, why then is the Sword of Sharpness a very rare weapon requiring attunement? What am I missing?

If my assumptions or arguments are wrong, please tell me, but to me this weapon seems like it should either have a lower rarity or have the first and second features synergize.

To add a higher level of objectivity, I am comparing both its damage output (no maximum damage against creatures, but 4d6 slashing on a crit and the chance to lop off a limb) as well as frequency of using its ability (1/20 to land a critical, 1/400 to lop off a limb) to those of other magical weapons of a similar rarity.

When using the Augury spell, how good or bad does the outcome of the course of action have to be to justify a response of Weal / Woe?

My players are planning to use Augury to decide whether to enter a dungeon, and I’m trying to decide what the outcome of the spell should be.

I can see that some extremes should be obvious: for example, if the dungeon contains four ancient dragons that will annihilate them, it’s Woe. If the dungeon contains a pile of platinum and no dangers at all, it’s Weal. But what if it’s a ‘typical’ dungeon with monsters and traps but also treasure? Does that count as Weal, Woe, Weal and Woe, or neither? What if, again as is often the case, there is danger first before there’s treasure? What if there’s a tough puzzle that might cause them to quit after taking damage but before finding treasure?

If it makes a difference, which I think it might, I would like them to explore this dungeon, and I think they have the skills to survive it and find the treasure. I’ve seen people suggest that Augury is really a way for the PCs to communicate with the DM, and if that’s the case, I would be tempted to say Weal, as code for ‘yes, please do it’. But I don’t want them to feel betrayed when they get (non-lethally) hurt.

As pointed out in comments, Augury only covers events in the next 30 minutes. I’d be interested in answers for both of the following situations:

1) This is a very short dungeon which can be cleared in less than thirty minutes; or

2) The players ask only about whether they should enter the first room of the dungeon – I think this exacerbates the problem because it’s even less clear whether this will be good or bad.

How to justify $f(n) = O(g(n))$ [duplicate]

This question already has an answer here:

  • Sorting functions by asymptotic growth 6 answers

The following question is in my homework:

Is the statement $ f(n) = O(g(n))$ true, when $ f(n) = n/2 + 4$ and $ g(n) = \sqrt{n} + 2\log_2 n + 3$ ?

I understand how $ f(n)$ is the upper bound of $ g(n)$ . However, I am unsure how to prove it mathematically.

Is it wrong to ask a player to justify their character’s actions?

When a player has their character do something completely outside of the perceived norm for that character, is it okay to ask them for a justification?

If they can not give satisfactory justification, would it be appropriate to have them take another course of action?

In my group, one of the biggest issues is meta-gaming. Characters doing things that they would have no cause to do, simply because their player has privileged information. It’s gotten so bad, my only recourse when I’m DMing has been to ask players to justify their actions. Some of my players are against this; others find it annoying, but understand as they have to do the same.

Even more so, though, we have an issue with people acting… well, random. Quite often, they will pick the most direct route to solve their problems, while completely ignoring anything near standard cultural norms, or even basic common sense. They will do things that, in any form of society, will get them into no end of trouble. Often times, their characters act more like a collection of stock cartoon-gags than actual people. Our group doesn’t have a regular DM because of this very issue. No one is willing to try and put up with dealing with the rest of the group as characters.

I tried providing in-game consequences for their actions. They were arrested, and then immediately assumed it was tantamount to a tpk. When I, or anyone, tries giving actions consequences, it only ever frustrates people, as one of two things will happen; either they continue acting random and without fail get their characters killed, or they throw on the breaks so hard to do a 180 with their characters’ personality that you can almost hear it.

The group averages from 19-24. It’s never been larger than six people, including DM. None of us can find a new group; we can never be sure what day we can meet, we’re the only players in a ten mile radius, we’ve all invested time and money into the current game and don’t have enough of either to find a new one, and there aren’t enough players to give up even one player, as every time we’ve added a player, they’ve left within the month because of scheduling issues.

So, we considered just making it a requirement that any given action taken by a character is subject to DM scrutiny, and will be ignored and re-done if found unsatisfactory as something said character might do. Is there any issue with that?

Trying to do a time skip, but how do I justify it to my players?

I want to run a game in Eberron, but start it on the Day of Mourning (using the adventure in the back of the 4E book), then advance the time four years. However, as I want to use 5E, I want them to use what amounts to four years of downtime. I don’t feel it’s fair to take that away.

But here’s the problem: I know they’ll try to say that they continue adventuring, but that undercuts the point of the time skip. I want them to be able to do everything except explicitly adventure. How would I justify telling them they can’t?

I initially thought about saying that Khorvaire is too unstable for adventuring to be viable, but that feels flimsy. Are there other reasons I could use?

How to justify using available code (in different language) for comparing algorithms

I have proposed an algorithm for a scheduling problem in a submitting paper. In the revision, the reviewer asked us to compare with another algorithm in the literature. Our algorithm is in MATLAB, and the comparing one is in C++, and the code is publicly available. We did not re-implement the C++ code, to avoid any decrease in the efficiency of their algorithm, and to save time as well. Now the reviewer is responding: “It is probable that there is a significantcant difference in performance between MATLAB and C++. The authors should make it clear if and how the results were normalized to ensure a fair comparison.”

So my question is this: Is there any (scientific) ratio or similar comparison between the efficiency of MATLAB and C++?

When we opted to use the available code, we thought it is completely OK since MATLAB is known to be slower. So using the comparing algorithm in a faster environment is OK. I should add that our algorithm is now performing much better than the comparing one.

How do you justify more code being written by following clean code practices?

I’ve been following some of the practices recommended in Robert Martin’s “Clean Code” book, especially the ones that apply to the type of software I work with and the ones that make sense to me (I don’t follow it as dogma).

One side effect I’ve noticed, however, is that the “clean” code I write, is more code than if I didn’t follow some practices. The specific practices that lead to this are:

  • Encapsulating conditionals

So instead of

if( != null && contact.emails.contains('@')

I could write a small method like this

private Boolean isEmailValid(String email){...} 
  • Replacing an inline comment with another private method, so that the method name describes itself rather than having an inline comment on top of it
  • A class should only have one reason to change

And a few others. The point being, that what could be a method of 30 lines, ends up being a class, because of the tiny methods that replace comments and encapsulate conditionals, etc. When you realize you have so many methods, then it “makes sense” to put all the functionality into one class, when really it should’ve been a method.

I’m aware that any practice taken to the extreme can be harmful.

The concrete question I’m looking an answer for is:

Is this an acceptable byproduct of writing clean code? If so, what are some arguments I can use to justify the fact that more LOC have been written?

The organization is not concerned specifically about more LOC, but more LOC can result in very big classes (that again, could be replaced with a long method without a bunch of use-once helper functions for readability sake).

When you see a class that is big enough, it gives the impression that the class is busy enough, and that its responsibility has been concluded. You could, therefore, end up creating more classes to achieve other pieces of functionality. The result is then a lot of classes, all doing “one thing” with the aid of many small helper methods.

THIS is the specific concern…those classes could be a single class that still achieves “one thing”, without the aid of many small methods. It could be a single class with maybe 3 or 4 methods and some comments.