# B Preserving Fresh Meat by spinning it at relativistic speeds?

1. Jul 7, 2017

### guigabyte

Let's assume there is a device that can hold fresh meat in a stationary position, and this device can spin at relatively high speeds. Would this allow fresh meat to last longer without freezing?

2. Jul 7, 2017

### scottdave

I guess it might, but it would take astronomically more energy than just running a freezer

3. Jul 7, 2017

### Ibix

You could put it in a high velocity centrifuge, yes. In principle.

But the energy cost to achieve significant time dilation is pushing the annual energy output of a country - per kilogram. And the centrifugal force would turn the meat into strawberry jam. And probably disintegrate the centrifuge with devastating consequences for any nearby cities.

Last edited: Jul 8, 2017
4. Jul 8, 2017

### Staff: Mentor

The meat would disintegrate. In addition, the center would not experience time dilation.

If the meat survives 1000 g and we build a racetrack around the whole Earth, we can give the meat a maximal speed of $v= \sqrt {R \cdot 1000 g} = 250 \frac{km}{s}$. This leads to a time dilation factor of 1.00000034. For 1 day for us, the meat experiences 0.03 seconds less. Not a very effective way to preserve it.

Let's make a big ring around Earth following the Moon's orbit. We can now achieve a speed of 1900 km/s. We now have a time dilation factor of 1.000019. For every day on Earth the meat ages 1.7 seconds less. Unfortunately the meat needs some time to get to this ring - much more than 1.7 seconds.

Let's dismantle Earth and replace it by a ring around the Sun with the same diameter as Earth's orbit. Now we can increase the speed to 40,000 km/s, more than 10% the speed of light. The time dilation factor is now 1.0084, for every day the meat experiences 12 minutes less. Still not very effecive. Note that "days" are not a good measure of time any more as there is no rotating Earth left in this scenario.

5. Jul 8, 2017

### sweet springs

Very interesting. Time dilation preserve food. I would like to add here a point of temperature. I am still puzzled freeze meet is cooled or warmed by motion?

6. Jul 8, 2017

### Staff: Mentor

Temperature and motion are independent.

7. Jul 8, 2017

### sweet springs

Some old books say differently $$T=T_0,T=\frac{T_0}{\gamma},T=\gamma T_0$$ I agree ice is ice for everybody not boiling water to anyone.

8. Jul 8, 2017

### Staff: Mentor

These equations are different relations between temperatures as seen by different frames, for different choices of the definition of temperature. If you want things to boil at the same temperature, for example, you need the first one, where temperature is the same in all reference frames.
You can freely choose the temperature of the meat in its rest frame independent of the velocity.

9. Jul 13, 2017

### davidge

Is the definition of temperature as $\partial U / \partial S$ still valid in this case?