Artificial intelligence overturns the standard theory of the
origin of the solar system
This is an excellent question because it touches on one of the most classic problems in the study of solar system formation. Let's break it down into two parts: what angular momentum means and why it causes headaches for planetary formation models .
What does angular momentum mean?
Angular
momentum is a
physical quantity that describes the
amount of rotational motion . It
depends on two things:
• how fast something spins or rotates
• how far the mass is from the axis of rotation
Everyday
analogy:
If you
spin on ice skates and bring your hands closer to your body,
the rotation speeds up. When you bring your hands further
away, the rotation slows down. The angular momentum remains
the same, but its distribution changes.
In the Solar System, angular momentum is distributed very unevenly :
• The Sun contains over 99% of the mass , but only about 1% of the angular momentum
• Planets contain less than 1% of the mass , but about 99% of the angular momentum
This is a physically surprising situation.
Why is this a problem for planetary formation theories?
1. The angular momentum distribution does not fit a simple model
If the
solar system formed from a single rotating cloud of gas (as
current theory suggests), angular momentum should be
distributed roughly along with mass.
But that's
not what happened.
The Sun is rotating too slowly compared to how much angular momentum the original cloud should have had.
This forces researchers to explain:
• How the Sun lost almost all of its angular momentum
• How the planets got it
Current explanations (magnetic braking, solar wind, disk viscosity) are possible, but not entirely without problems.
2. The condensation of gas and dust into planets is difficult
Gravity alone is not enough to explain how small particles grew into planets because:
Gas pressure resists condensation
Gas tends to spread, not accumulate.
Magnetic fields interfere with accumulation
The strong magnetic field of a young star can:
• blow off gas
• prevents dust accumulation
• slows down the movement of the puck
Dust particles do not stick together easily
Within a certain size range (from millimeters to meters), particles:
• collide and break apart
• fall rapidly towards the star
• do not grow large enough before they are destroyed
• This is called the " meter-size barrier".
3. Planetary orbits and compositions don't always fit models
For example:
• Why are the inner planets rocky and the outer planets gas giants?
• Why didn't Jupiter grow even bigger?
• Why have some planets changed their orbits (migration)
• Why is there so little iron on the Moon?
• Why do some asteroid belt objects appear to have formed at different temperatures?
All of this suggests that the formation of the solar system was more complex than the simple "gas disk → planets" model.
Summary
Angular
momentum =
amount of rotation.
In the
solar system it is distributed strangely: the Sun is massive
but rotates slowly, the planets are light but rotate
quickly.
Problems in birth models:
• The Sun lost its angular momentum in a way that is not fully understood
• Gas and dust do not naturally condense into planets
• Magnetic fields and pressure prevent accumulation
• There are critical size classes in the growth of dust particles, where growth stops
• The orbits and compositions of the planets do not fully fit simple models
