# Does the Earth's revolution around the Sun affect radioactive decay?

Premises:

1. The radioactivity is either hastened or slowed inside a fast moving aircraft.
2. Speed of fastest aircraft: 3,529.6 km/h.
3. The earth's revolution is: 107278.87 km/h.
4. The earth's revolution is significantly higher than the speed of moving aircraft.

Questions:

1. Are all the premises correct and if not, which part is not correct?
2. Does this mean that the earth's revolution affects modern dating methods?

Sources:

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Many earth events which are dated happened also on earth so they were also moving with the same speed, they are in the same lab frame if you will. And since you mentioned creationism - yes god exists indeed :D though he does not need prove or dating from us. – Asphir Dom Sep 22 '12 at 15:39

Where did you get that figure for the speed of the Earth's surface? The circumference of the Earth at the equator (it's greatest circumference) is 40,075km and it rotates once in 24 hours, so the speed is 40,075/24 or about 1,670 km/hour or 464 m/sec.

If you calculate the time dilation at 464 m/sec it's insignificant, as you'd expect given that this speed is 0.0000015$c$.

Response to comment:

The velocity of rotation around the sun is about 29,800 m/sec (0.0001$c$), and at this speed the time dilation factor is about 0.999999995. This gives an error of about 23 years over the 4.54 billion lifespan of the Solar System.

But in any case you need to define what you mean by the time. If a physicist uses radioactive decay to measure a date then because the physicist is moving at the same speed as the radionuclide the physicist and the radionuclide experience time flowing at the same rate. That means that by definition there can't be any dating errors.

Response to response to comment:

Suppose a block or Uranium-238 split in two at the beginning of the Solar System, 4.54 billion years ago, and one half ended up on Earth while another half ended up on Pluto. On the Earth a physicist dated the formation of the Solar System by measuring how much of the U-238 had decayed, while on Pluto an alien physicist did the same experiment. The two physicists would come up with different ages i.e. they would measure that different amounts of the U-238 had decayed.

This is a real difference: time really does flow at a slightly different rate on Earth and on Pluto, though the difference is so small that you'd never actually be able to measure it. Some of the difference would be due to the different orbital velocities of Earth and Pluto, and some would be because Earth is deeper into the Sun's potential well and gravity affects time as well. I'd have to sit down with a pen and paper to work out which effect was stronger.

Although the time dilation is insignificant for the Solar System gravitational time dilation can be significant for neutron stars and especially for black holes. In fact if you sat some distance from a black hole and watched someone falling into it you'd see time for the falling astronaut slow to a stop as they approached the black hole event horizon.

One last comment:

You might be interested in this article. I've already mentioned that the gravitational field of the Earth affects time, and this has been used to measure the Earth's geoid by measuring the differences in the rate atomic clocks run.

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You're giving rotation, the figure I'm giving is the earth's revolution around the sun. – helix Sep 21 '12 at 17:32
But we all go round the Sun at the same speed, so we would experience time at the same rate as the radionucleotides. The travel round the Sun couldn't cause dating problems. I suppose an alien sitting on Pluto might beg to differ ... – John Rennie Sep 21 '12 at 17:41
So, universally speaking, does it or does it not? – helix Sep 21 '12 at 17:43
even so, 30km/second are a tiny fraction of the velocity of light 299 792, 458 km / s for time dilation to be significant between planets. On the earth itself, as John says,we are all in the same frame. – anna v Sep 21 '12 at 17:53
Does "universally speaking" make sense WRT special relativity and reference frames? – horatio Sep 21 '12 at 17:53