Recent content by peety

If we assume he is skidding and ignore friction, isn't this the pole in barn paradox (but with not-fitting instead of fitting)? In his frame the hole is safely contracted; from the hole's point of view the heel and toe strike at different times and so again don't enter.

I suppose that as medical intervention and surgical technology improves we move towards survival of the less fit but more desired by the more affluent. Just as we have bulldogs with breathing problems we'll have more people with weak hearts and other survival disadvantages.

When Einistein was moving towards his General theory and realized that there had to be something inadequate in giving priority to certain reference bodies or their state of motion wasn't this a kind of philosophical insight? Maybe we could view physics as an extraordinarily precise and empirical...

Relativity absolutely wrong sounds like a play on words.

Is there a good definition of 'preferred frame'? Wikipedia refers to a frame where the laws are 'different/simpler' as if that isn't a problematic distinction. In Ptolemaic times when the Earth provided the preferred frame descriptions of orbits were not just over-complex but fundamentally...

Just a brief comment on why the twins appear to present a paradox: we confound equivalence with symmetry.

It's all a matter of what you stipulate. If you stipulate that its speed is constant then it doesn't slow down, if you stipulate that it slows it slows. Is this about velocities and directions?

Thanks, I must have misundertood Dale's post.

Presumably there is a reason why this qualification doesn't suggest the possibility of transmitting information faster than light. If this is so, why? Would information break down? Would quantum aspects come into play? Should we say that nothing can go faster than light but light can travel...

If the lab is 300,000 km long and you are in the lab you will time 1 second regardless of whether you are moving. An outside observer, given the right set up, will see the lab 150,000 km long and time half a second. He will also see your rods halved in length, but you won't. See the Ehrenfest...

It seems that a lot of these lengthy discussions are held up because of the temptation to slip out of the agreed frame of reference. Imagine (classical physics) a flight attendant on a plane is pushing a trolley forwards and at the same time moving a pot backwards. We are asked to calculate the...

More simply, it is a given that the passenger is at rest in his/her frame and therefore cannot conclude that s/he is 'moving towards the information that is arriving...'

Is Is there an easy way to show how you get from here to the v squared over c squared of Lorentz?

Thanks - that's very clear and helpful. I always thought setting these thought experiments on the Earth confused things, but I like familiar territory.

I'd just like a little clarity about the right terminology. Alfred is at rest in a train at a station. On his left Henry is in a train that suddenly accelerates forward with the result that he spills his coffee. Henry concludes that he is at rest in a gravitational field that results in the...