# What are your favourite physics/mathematics misconceptions?

• ergospherical
In summary: So, the definition of force is an approximation that needs to be refined over time? Interesting.In summary, this conversation is discussing how the definition of force is an approximation that needs to be refined over time.
As a kid, I thought we could get rid of our nuclear waste by shooting it into the sun only using the sun's gravity. Now I know, that this plan has a little momentum problem. But on the other hand, I have a new idea: why not use the waste for generating electric energy for a small magnetic field so that the radiation can be turned into an ion thruster?

Keith_McClary
Better yet - if you have a Kerr black hole handy...

Source: MTW.

Keith_McClary and fresh_42
fresh_42 said:
As a kid, I thought we could get rid of our nuclear waste by shooting it into the sun only using the sun's gravity. Now I know, that this plan has a little momentum problem. But on the other hand, I have a new idea: why not use the waste for generating electric energy for a small magnetic field so that the radiation can be turned into an ion thruster?
I actually saw a presentation about launching waste into orbit in the late nineties. If memory serves, putting the stuff in an orbit inside of Venus is “reasonable.” The big problem is Earth’s gravity well. Large amounts in a single launch has safety problems in case things go wrong. The proposal I saw proposed launching small volumes to get around this. Another issues is getting the material to a launch site. A lot of the waste is a sludge in decaying barrels. The total amount is extremely large in the context of moving or “processing” it for launch.

fresh_42 said:
This only happens to famous skeletons, and only if someone who is alive starts it!
Newton would rotate in his grave.
What kind of angular momentum would he have?

jedishrfu said:
What kind of angular momentum would he have?

jedishrfu

• Topology and Analysis
Replies
4
Views
2K
• Special and General Relativity
Replies
29
Views
2K
• Classical Physics
Replies
0
Views
136
• Other Physics Topics
Replies
36
Views
4K
• General Discussion
Replies
8
Views
2K
• MATLAB, Maple, Mathematica, LaTeX
Replies
3
Views
275
• New Member Introductions
Replies
2
Views
249
Replies
1
Views
810
• STEM Career Guidance
Replies
10
Views
3K
• Beyond the Standard Models
Replies
30
Views
7K