There are a few things that never change
Table 1: Physical Constants (SI units)
| constant | symbol | value | units |
| Avogadro's number | N | 6.02E+23 | mole-1 |
| Boltzmann constant | k | 1.381E-23 | J/K |
| Electric Charge | e | 1.602E-19 | coulomb (C) |
| Gas Constant | R | 8.3145 | J/K*mole |
| Gravitation | G | 6.672E-11 | N*m2/kg2 |
| Mass | electron | 9.11E-31 | kg |
| Mass | proton | 1.67E-27 | kg |
| Mass | neutron | 1.68E-27 | kg |
| Mass | alpha-particle | 6.64E-27 | kg |
| Plank's | h | 6.626E-34 | J*s |
| Plank's | hc | 1.986E-25 | J*m |
| Plank's | hc/k | 1.439E-02 | m*°C |
| Radiation constant | hc^2 | 5.955E-17 | W*m2 |
| Speed of light | c | 2.998E+08 | m/s |
| Stefan-Boltzmann | sigma | 5.6705E-08 | W/m2*K4 |
If there are others out there, this is how they'll find us
Table 2: Astronomical Constants (SI units)
| constant | body | value | units |
| Gravitational Acceleration |
Sea level | 9.8067 | m/s2 |
| Luminosity | Sun | 3.826E+26 | J/s |
| Mass | Sun | 1.989E+30 | kg |
| Mass | Earth | 5.976E+24 | kg |
| Atmospheric Pressure |
Sea level | 1.013E+05 | Pa |
| Radius | Earth | 6.371E+06 | m |
| Radius | Sun | 6.970E+08 | m |
| Earth's Orbital | Velocity | 2.978E+04 | m/s |