# Can two things happen at EXACTLY the same time?

1. Jan 30, 2012

### michael98

sorry if i typed this too hard to understand. im also new to this stuff so dont make fun of me if this is actually an easy question.

is it possible for two things to happen at the same EXACT time? for example, if two cars were racing to see who could get the fastest time and they both got a time of 10.5 seconds, you would need to to look at the hundreths of the second to see wich car's time was faster. but if the times were still the same in the hundreths of the second, then you would look into the thousandths of the second. if every time you looked into a smaller portion of the second and it still came out with the same time, you would either keep doing this for infinite or until you finally saw that one car had a faster time. so does this mean two things cant happen at the EXACT same time?

2. Jan 30, 2012

### Drakkith

Staff Emeritus
You could conceivably keep getting further down into shorter time periods, but somewhere along the line you will run into the problem of not being able to measure them. So the short answer is that yes, to the best of our measurements it is possible for two things to happen at the same time. Beyond that is beyond my ability to answer.

3. Jan 30, 2012

### Nabeshin

A theoretical example of two things happening at the same time would be pair production, where photons produce an electron and a positron. Both the electron and positron were 'produced' at EXACTLY the same time (One might say that the two are precisely as old as each other. If you had particles that decay, instead of electrons, this might be something you could measure).

4. Jan 30, 2012

### Antiphon

Technically you cannot say that any two things happened at the exact same time unless they also happen at the exact same place. The conclusions about which thing happened first or whether things happened at the same time will depend on how the things (and the referee(s) are moving.)

5. Jan 31, 2012

### Lsos

Is there something like "planck time"? I guess I don't know. But surely if it was possible for two things to hapen exactly simultaneously, they will not be everyday things (like racing cars) but quantum effects/ singularities at best.

6. Jan 31, 2012

### Studiot

I would just like to point out that there is a difference between the same 'temporal coordinate, which is what all the reponses have been about so far and what the OP gave in his example which is a time interval.

The actual answer depends upon what you are prepared to allow and the original conditions were rather loosely defined.

So for instance, someone is going to bed in Sydney at the same 'time' as someone else is getting up in Moscow.

Say one of the cars was in Moscow and one in Sydney and the run took 1.372 minutes. Is the question 'is this the same in Moscow and Sydney'?
Suppose both races lasted 48 hours and commenced within 24 hours of each other, we could definitely state that for any observer there will be a time when both cars are in motion together.