What is Actually Quantum Mechanics Forbids This?

It is a reaction image cut from PBS Space Time showing host Matthew O'Dowd next to the on-screen line "Actually, Quantum Mechanics Forbids This," used to mock-refute someone else's take.

Where did Actually Quantum Mechanics Forbids This come from?

The frame comes from the PBS Space Time YouTube episode "Why Quantum Information is Never Destroyed," uploaded on May 23, 2018, with the text appearing around the 4:30 mark.

What does Actually Quantum Mechanics Forbids This mean?

It's used to shoot down an opinion or statement in a hyperbolic way, as if a physicist has just declared the claim impossible under the laws of quantum mechanics.

How do you use Actually Quantum Mechanics Forbids This?

Keep the O'Dowd frame and swap the on-screen text for whatever statement you want to refute, the way early Redditors did with lines like "I play Fortnite but I'm not gay".

Is Actually Quantum Mechanics Forbids This still popular?

It peaked as a Reddit format in May 2018 across r/MemeEconomy and r/dankmemes and is treated as a classic refutation macro from that era.

Actually Quantum Mechanics Forbids This

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Published August 15, 2026

"Actually Quantum Mechanics Forbids This" is a reaction image cut from a May 2018 PBS Space Time episode, showing host Matthew O'Dowd next to the on-screen phrase. Redditors picked it up the same day it aired to shoot down other people's takes with mock scientific authority.

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Overview

"Actually Quantum Mechanics Forbids This" is a reaction image built from a still frame of astrophysicist Matthew O'Dowd hosting an episode of the PBS digital series Space Time1. In the frame, O'Dowd stands to the side while the phrase "Actually, Quantum Mechanics Forbids This" sits in large white text on screen1. The visual reads like a physicist calmly ruling something out of existence, which is what made it useful for Redditors who wanted to shoot down a claim with mock scientific authority3.

The joke works on the mismatch between the serious science-explainer source and the trivial statement being "forbidden." Posters swap in opinions, preferences, or hot takes that have nothing to do with physics2. The template stays fixed each time: keep O'Dowd's frame, change the on-screen line to whatever the poster wants to refute4.

Gallery

Origin & Background

Platform

YouTube (source frame) / Reddit (viral spread)

Date

2018

The source video, "Why Quantum Information is Never Destroyed," was uploaded to PBS Space Time's YouTube channel on May 23, 20181. Around the 4:30 mark, O'Dowd is walking through the laws of quantum physics when the line "Actually, Quantum Mechanics Forbids This" flashes on screen1. The episode itself pulled more than 129,000 views on YouTube1.

Later that same day, Redditor TheShayminex 2 posted a screen capture of the moment to r/MemeEconomy with the caption "I like traps but I'm not gay," a callback to the earlier "Are Traps Gay?" template3. The post cleared 19,000 points at 88% upvoted and drew about 3,400 comments in its first 24 hours2.

How It Spread

The image jumped subreddits within hours. Redditor Kingmenudo 4 posted a version in r/dankmemes captioned "'Black people can not be racist,'" which hit roughly 475 points at 96% upvoted4. Back on r/MemeEconomy, user glimpim01 2 pushed the format with "I play Fortnite but I'm not gay," pulling in more than 1,000 points and about 70 comments in a day2.

By the end of the same day, Redditor vanillaworldwarcraft 4 had swapped in a still from a YouTube tutorial titled "ROBLOX: How To Make Boobies (No Morph)," using the format to declare that particular guide physically impossible4. That post cleared 600 points at 97% upvoted4. The rapid multi-subreddit adoption in one day is what pushed the image out of an investment-post joke on r/MemeEconomy and into a general-use refutation macro3.

How to Use This Meme

People typically drop the O'Dowd frame in as a reply when someone posts a stance they want to mock, then edit the on-screen text so it reads back the "forbidden" claim in the poster's own words2. The common convention is to keep the layout untouched other than the white text line, so the physics-lecture framing stays intact and the joke lands on the mismatch4.