# Is time a mathematical entity or there is any demostration of its existence? [duplicate]

I an having trouble trying to understand time as a physical entity. We can demonstrate the existence of air, the source of infection, electromagnetism, voltage, amperage, among many other physical entities. We can measure, weigh or see these items but when it gets to time my brain stops.

Does time have a physical manifestation, is it a particle or simply time is a mathematical expression. A constant pushed into formulas?

• What kind of demonstration would convince you? I suspect you want a physical manifestation that "looks" like other things in the physics lab, such as a voltmeter moving or air in a container responding to pressure and volume changes? But if you accept the voltmeter, why not the clock? – Anders Sandberg May 11 '19 at 8:16
• Possible duplicates: physics.stackexchange.com/q/17056/2451 , physics.stackexchange.com/q/195290/2451 and links therein. – Qmechanic May 11 '19 at 8:18
• Possible duplicate of What is time, does it flow, and if so what defines its direction? – John Rennie May 11 '19 at 9:20
• I have read the 4 related questions and still it does not get to the point. Some say it is a mathematical entity, others say that time is what it is being measured by a clock. Other opinions relate time with space and connect it with relativity and it does not make any sense. Accept it like this is without an explanation, A demonstration is not an explanation. If time works in a formula to predict a position, a velocity is only a constant. Still time is not an object with properties, or is it? – caranax May 11 '19 at 15:07

In special relativity, i.e., in physics, spacetime is on a united footing. If you think that space is physical, there is good enough (and unavoidable) reason for you to say that time is physical. The experimental evidence for special relativity being true is tremendous. More strikingly, in general relativity (which makes the GPS work and has been proven incredibly accurate in multiple ways), spacetime is not only physical, it can change, i.e., it is dynamical--in particular, spacetime has $$20$$ degrees of freedom at each point. So, yes, time is very much physical.