You are here:

# Physics/Space/Time

Question
QUESTION: As I understand it both space and time are relative to the speed of light but if they were combined into 4 dimensions (three of space, one of time) it together would be absolute? What keeps that from being our way of measuring things?

ANSWER: It doesn't work that way, really.  Both time and space are relative to the objects measuring them.  The concepts are truly difficult to wrap your head around, because in our day-to-day life there are few examples which your senses can directly perceive.  Quantum mechanics is much the same.  With instruments and proper measurements, both theories are ridiculously well-tested.  We should start changing the language to call it "Newton's approximations," which are a result of the speed of light being very high within "Einstein's Laws of Relativity."

---------- FOLLOW-UP ----------

QUESTION: I ask because I was thinking since space is measured in inches, mm, cm, or whatever and time is measured in time type measurements I was wondering if something like a plank length which is partly based on the speed of light could be used as a form of unit that could used for time and space dimensions?

Unit yes.  Absolute measurement, no.  There is no such thing, that's the problem you're having with the concepts.  You're trying to ascribe an x, y, z (and t?) and such to things which can be totally thrown by rotation.

Just keep in mind the principles of relativity.  They basically boil down to this...the same physics has to work for all observers.  That's it, it's not physics if everyone doesn't see it work (work in accordance with the laws, not see the results) the same way.  You base your math and science on this simple principle and you get relativity.

Physics

Volunteer

#### Dr. Stephen O. Nelson

##### Expertise

I can answer most basic physics questions, physics questions about science fiction and everyday observations of physics, etc. I'm also usually good for science fair advice (I'm the regional science fair director). I do not answer homework problems. I will occasionally point out where a homework solution went wrong, though. I'm usually good at explaining odd observations that seem counterintuitive, energy science, nuclear physics, nuclear astrophysics, and alternative theories of physics are my specialties.

##### Experience

I was a physics professor at the University of Texas of the Permian Basin, research in nuclear technology and nuclear astrophysics. My travelling science show saw over 20,000 students of all ages. I taught physics, nuclear chemistry, radiation safety, vacuum technology, and answer tons of questions as I tour schools encouraging students to consider careers in science. I moved on to a non-academic job with more research just recently.

Education/Credentials
Ph. D. from Duke University in physics, research in nuclear astrophysics reactions, gamma-ray astronomy technology, and advanced nuclear reactors.