My players are currently in a futuristic setting where they are being shot at by lasers and such. One of my players tried to justify that an antimagic field should be able to disable future tech because it's "basically magic". My understanding is that all magic comes from The Weave, and anything outside of that is just considered technology (like an electric light bulb). Am I wrong in this assumption?
[RPG] Is future technology that is almost indistinguishable from magic considered a “Magical Effect”
dnd-5emagic
Related Solutions
Dispel Magic Only Ends Spells
A magical effect that is not the result of an ongoing spell cannot be dispelled.
Jeremy Crawford has issued several Twitter rulings to this effect.
In this Tweet:
Q: Can dispel magic undo a druid's wild shape
A: Dispel magic ends spells. Wild Shape isn't a spell.
and this one:
Q: Does Dispel Magic auto work vs Channel Divinity powers? Ie.. Paladin's Vow of Enmity magic effect.
A: Dispel magic ends spells. A Channel Divinity option like the paladin's Sacred Weapon isn't a spell.
Q: Does dispel magic effect an arcane ward?
A: Dispel magic ends spells. Arcane Ward isn't a spell
Q: Does that mean magical items cant be dispelled either? We've assumed that they could be disabled temporarily with dispel.
A: Dispel magic can end spells that come from a magic item, but it has no effect on the item itself.
Also note that Dispel Magic can only end spells with an ongoing duration. It cannot remove the lingering effects of an instantaneous spell. PHB P. 203:
Many spells are instantaneous. The spell harms, heals, creates, or alters a creature or an object in a way that can't be dispelled, because its magic exists only for an instant.
The March 2016 Sage Advice Column covers Dispel Magic as well. It reiterates that Dispel magic cannot end magical effects that are not the result of a spell, such as a vampire's Charm effect. It also reiterates the rule about Dispel Magic not working on the results of a spell with an instantaneous effect. It adds that a readied Dispel Magic cannot be used in place of a Counterspell, though in some limited circumstances, it may be almost as good.
To answer your actual question, in this context, targeting a magical effect clearly means you can target just one specific ongoing spell effect instead of stripping everything on a particular creature.
They are not detectable with detect magic
Detect magic can only detect creatures — even highly magical creatures such as outsiders and elementals — if they are the result of an ongoing spell, such as summon monster. No creature type detects as magical in itself, not even undead. Specifically, the spell has listings for magic items and for spells, and for nothing else.
But they are Magical Beasts
Familiars (emphasis added):
A familiar is an animal chosen by a spellcaster to aid him in his study of magic. It retains the [majority of the game stats] of the normal animal it once was, but is now a magical beast for the purpose of effects that depend on its type.
Generally, any animal that becomes too smart for the confines of the Animal type (2 Int or less) becomes a Magical Beast by virtue of specific wording of whatever effect is responsible for the Int increase; there is, as far as I know, no general rule to ensure this in all cases.
Best Answer
Technology is not considered to be a magical effect unless it is powered by magic
A player's perception of what appears to be magical or not has no bearing on the rules for whether it actually is considered to be magical by the rules. The only thing that matters is the magical nature of the object.
Something must be connected to the weave to be considered magical regardless of the technological level of your campaign/item. That is what defines being magic. There are many things in the D&D world which look magic and are not, as well as things that don't look magical at all but are.
Sage Advice gives us the rules for determining if something is considered magical:
By the book - lasers/future tech are non-magical
By default, D&D does not provide details on how technology works, but it does give us examples of specific items in the DMG on p. 268 (including laser rifles and other such items). As listed in the book, these definitely are not magical because the weapons do not pass any of the tests listed above for magical items.
You have indicated that this is the way you also are treating technology in your campaign. In this case, anti-magic field would certainly not affect any tech in the game because of its lack of magical nature.
If you are making your own technology - it is up to you
However, a DM looking to add detail could certainly add to or change what the book says. Also, not all technology has to be treated in the same way as long as it makes sense in the world and is clear to the players.
If you are making your own custom setting/tech then you get to decide the answers to these questions with regards to how technology works in your world.
If you decide that technology is powered by spells or magic then they would be magical.
If you decided that your technology is based off of in-world science (and completely devoid of any connection to the weave or any kind of spells) then it would not be considered magical.
Only magic and magical effects are affected by an anti-magic field.
Either way, the perception that something is magical has nothing to do with what the rules consider to be magical.
Sidenote: by default, there are always tools to distinguish between magical and non-magical things
Your (original) title said that you are referring to something technological that is "indistinguishable" from magic (presumably referring to Clark's Third Law). That technically isn't possible given how the game concretely defines magic and even gives you tools to determine if something is magical or not (identify, detect magic, antimagic field). Since there is a concrete definition of what is magical there are in-universe tests to determine if that is the case. In other words there is theoretically always a way to distinguish between technology and magic if you try hard enough and have the tools. This doesn't really change anything about the nature of this answer or your question, but I thought it was worth noting.