Relativity of simultaneity

End of section 8 Section 9.

The Relativity of Simultaneity.

Up to now our considerations have been referred to a particular body of reference, which we have styled a railway embankment.

We suppose a very long train, travelling along the rails with the constant velocity v, and in the direction indicated in figure 1.

End of section 8 Section 9.

The Relativity of Simultaneity.

Up to now our considerations have been referred to a particular body of reference, which we have styled a railway embankment.

We suppose a very long train, travelling along the rails with the constant velocity v in

We thus arrive at an important result.

Events which are simultaneous with reference to the embankment are not simultaneous with respect to the train, and vice versa.

Relativity of Simultaneity Every reference body has its own particular time.

Unless we are told the reference body to which the statement of time refers, there is no meaning in a statement of the time of an event.

There is no illusion.

Simultaneity, the idea that two events happen at the same moment, is not a universal fact.

It depends on who is measuring and how they are moving.

To make this concrete, imagine a specific scenario.

There is no master clock, no universal referee, no god's eye view that can settle which account is the true one.

Both are true.

Simultaneity is relative.

At sublight speeds, this relativity of simultaneity is strange but harmless.

It is far more than that.

Simultaneity is the deeper wound.

Time dilation tells you that clocks disagree on how much time has passed.

The relativity of simultaneity tells you that observers disagree on what is happening right now.

Both observers are correct.

Neither is deluded.

Simultaneity, at cosmic distances, is observer-dependent even at walking speeds.

The Andromeda Galaxy is not an extreme case chosen to exaggerate the point.

Section 9.

The Relativity of Simultaneity Up to now, our considerations have been referred to a particular body of reference, which we have styled a railway embankment.

We suppose a very long train traveling along the rails with a constant velocity v.

Hey guys, Lady Luck here.

We thus arrive at an important result.

Events which are simultaneous with reference to the embankment are not simultaneous with respect to the train, and vice versa.

Relativity of simultaneity.

Every reference body, coordinate system, has its own particular time.

Section 9.

The Relativity of Simultaneity Up to now, our considerations have been referred to a particular body of reference which we have styled a railway embankment.

We suppose a very long train traveling along the rails with a constant velocity v and in the direction indicated in figure 1.

People traveling in this train will with advantage view the train as a rigid reference body, coordinate system.

We thus arrive at an important result.

Events which are simultaneous with reference to the embankment are not simultaneous with respect to the train, and vice versa.

Relativity of simultaneity.

Every reference body coordinate system has its own particular time.