xkcd #3085: About 20 Pounds
xkcd #3085: About 20 Pounds
Title text:
In addition to gravity, burritos interact through the strong, weak, and electromagnetic forces, which is believed to be a major contributor to their popularity.
Transcript:
[Cueball and Ponytail are standing in front of a pentacle with lit candles at the corners. A black sphere, the oracle, is floating above the middle of the pentacle.]
Ponytail: Dear oracle,
Ponytail: What is the nature of dark matter?
Oracle: It's about 20 pounds.[Close up of oracle]
Off-panel: What?
Oracle: Dark matter is a particle. It weighs about 20 pounds.
Oracle: It only interacts through gravity.[Same view as first panel]
Cueball: Only gravity, huh?
Cueball: So none of our experiments are really going to tell us any more about it, then.
Oracle: Afraid not.[Same view as first and third panels, except Cueball lifted his forearm.]
Cueball: So what do we do?
Oracle: You should go out for burritos.
Ponytail: How will that help?
Oracle: Well
Oracle: Burritos are pretty good.
Source: https://xkcd.com/3085/
If a particle really only interacted with gravity, would it pass through matter? AFAIK "touching" things is electron repulsion...
Looking at it from a quantum field perspective, pretty much. If the only interactions are through gravity then the underlying field's evolution can't be influenced by anything else, I have no real idea what the implications of that would be because we don't have a QFT for gravity.
Mmm. Burrito.
This is a funny comic, but it really does disturb me how certain most theoretical physicists are about the nature of dark matter, despite there not really being any good philosophical reason for us to expect these anomalies to be caused by a particle that interacts non-gravitationally.
Here's the best evidence of difficult to detect matter likely being real. You wouldn't see such a shift in gravity if there aren't matter unaffected by friction