3 ms·

can we measure that imprecision of momentum/position relation even though small?

• steve76 8y ago
  h/2pi ? That likely applies to not just light, but everything. Do we really need that much precision to get what we want? Can we flip it, and just say as long as we can do that, there's still hope to spark up another big bang when everything is cold and expanded? Are they doing something useful by asking these questions or just trying to make a name for themselves, or learn on your dime?
• anongraddebt 8y ago
  I believe gus_massa was just saying that we simply define out of existence this supposed problem with measurement (for macro objects). This is done because even though the 'furniture of the world'/everyday objects/macroscopic objects are still quantum entities, at this level, error rates are such that they can be treated in a classical manner.
• AnimalMuppet 8y ago
  No. It would take far more digits of accuracy than we can measure. For example, here's an object of 1 kg mass. The product of the uncertainty of its position and momentum is h-bar / 2, or h / 4 pi, which is about 5e-35 kg m^2/s. We're going to measure the position to one wavelength of visible light (say, 500 nm wavelength, so 5e-7 m). That means that we need to be able to measure the momentum to an accuracy of 1e-28 kg m/s, which for a mass of 1 kg means measuring the velocity to within an accuracy of 1e-28 m/s. Good luck with that...
  • aj7 8y ago
    Good reply.
• spaced-out 8y ago
  One of my homework assignments in a quantum mechanics class was to calculate the uncertainty of a cheetah that was running at 65 mph (and given its weight). You can in theory but the numbers get so small that they're clearly unmeasurable.