Flavor Flav knows what time it is. At least he does for Flavor Flav. Even with all his moving and accelerating, with the planet, the solar system, getting on planes, taking elevators, and perhaps even some light jogging. In the immortal words of Kool Moe Dee. Do you know what time it is?

Didn't Einstein tell us it's all relative? Does anyone actually know what time it is? I mean, aside from figuratively, or in a political sense, or perhaps as part of rap performance from whence the power is being fought from, requiring the sick skills of a hype man wearing a clock around his neck on a big chain.

So, after all my fancy dancing and longing for a time in rap and hip hop from days gone by, I must present to you "faithful audience member" an answer in the form of your 3 least favorite words I get to deliver.

It all depends…

You have heard that everything is relative, usually we hear it from people who like to talk about "connections on many different levels", which is just nonsense.

But in physics "everything" is relative in a very particular way. Everything is relative to the speed of light, which is the same in every reference frame. Which is confusing and repeated enough that it can become meaningless.

So I'm going to do my best to explain it. If I shine a flashlight in front of me, I will measure the beam to travel at about 300,000 km/s, which is also known as the speed of light.

And if you are moving at 200,000 km/s faster than me, and shine a flashlight ahead of you, I will see the light from your flashlight moving at the 300,000km/s. It will appear to me, as though the light from your flashlight is moving away from you at 100,000 km/s.

But when you will measure the speed of that light, relative to you, you'd think it'd be moving at 100,000 km/s as well, but instead from your perspective it will ALSO clock in at 300,000 km/s.

The speed of light. How is this even possible? It is possible in part because the rate at which you experience time relative to me changes. For you, time will seem normal, but from my perspective your time will seem slower. We agree on how fast light is moving in kilometers per second, but we disagree how long a second is. We also, by the way, disagree on the length of a meter.

This seems strange because we imagine that space and time are absolute things, and light is something that travels through space. This is our experience. Suggesting things like time and space are malleable values at best is unsettling and at worst will make us nanners from thinking too much about.

Hold on to your tinfoil hats, for it is in fact light that is the absolute, and space and time are relative to it. So what time it is depends upon your vantage point, and so there is no single absolute time.

Finally, because of relativity, each point in the Universe experiences time at a slightly different rate. For example, when we observe the cosmic microwave background, we find that we are moving at a speed of about 630 km/s relative to the background. That means we experience time a bit more slowly that something at rest relative to the cosmic background.

It's just a tiny bit slower, but added over the entire age of the Universe, our cosmic clock is 30,000 years behind the times. Feel free to set your watch. But don't get too precise about it. Your time could be off by tens of thousands of years.

**Explore further:**
Special relativity from first principles

## Doug_Huffman

He mentions the difficulties with absolute and relative time late in his devil's advocate first half of the book. I am particularly fascinated by the intersection with Karl Popper, both his 'Logic' and 'Open Society'.

## Jixo

Aug 29, 2014## arom

Aug 29, 2014## Urgelt

Answer: you wouldn't perceive any. You could travel across billions of light-years, but for you, no time would pass at all on your journey. You would depart and arrive instantaneously.

At least, that's according to Einstein's theory.

And photons are missing the whole cosmic show; for them there is no dance of galaxies, no ticking of clocks, no cosmic expansion, no rise or fall of self-proclaimed sapient species. Photons are emitted and absorbed in an instant, no matter how far we perceive them to travel.

Regarding the cosmos as enduring only for an instant and having no perceptible distance is rather mind-boggling. But that's a valid perspective - if you're a photon.

## OceanDeep

Yes, that is mind-boggling. Does that mean that from a photon's frame of reference, they don't move at all, but rather just blink in and out of existence at various locations in the universe?

## Da Schneib

## antigoracle

Even when they pass through a double slit?

## Mimath224

## kevin_proudler_73

Meanwhile, everywhere else in the world these days, all you will see are the complex explanations of Special Relativity which always include math, and NEVER fully encompassed Special Relativity's entirety.

However, when fully understood, Special Relativity can be explained in only 1 hour and 39 minutes. The absolute foundation that creates all the bizarre relativistic outcomes, is fully revealed.

See http://goo.gl/fz4R0I

This exposure is then violently opposed by those whom are caught up in relativistic circular reasoning. They refuse to accept any possible absolute cause of Special Relativity. In turn they continuously demand that there is an effect, but in no way is there a cause.

## AmritSorli

http://article.sc...3.11.pdf

## Aligo

Aug 30, 2014## Aligo

Aug 30, 2014## Aligo

Aug 30, 2014## Da Schneib

The analogy breaks down in the two dimensions that the photon is not moving in. I was going to mention it but figured I'd keep it clean and deal with that part if anyone asked. ;)

ETA: I can't believe someone gave you a 1 for that. You got a 5 from me. It was a great question and above all things, I respect good questions. Schneibing is asking good questions, and I am the Schneibster.

## Da Schneib

The direction of time's arrow is determined by the hyperbolically symmetric shape of time; it can go forward down the axis of the "front" of the hyperboloid of revolution, or it can go along the "back" hyperboloid, or it can skew out to the limits of the hyperboloid. But that is all.

contd

## Da Schneib

Remember also that for two observers in IRFs that are comoving, but not colocated, the frequency cannot change. Remember conservation of energy? That's why. Note however that this implies that energy is not a constant among IRFs that are not comoving. A lot of people who study relativity fail to get it at this point. It should be obvious; objects at different positions in a real gravity field have different potential energies, too. Energy is fungible among non-co-moving IRFs. It can be exchanged for velocity relative to its source.

## Da Schneib

Just askin'.

## Da Schneib

Just sayin'.

## TechnoCreed

I gave a '5' to Kevin S. Prouler and wondered who could possibly give a '1' to this guy. So I was perplexed until I saw your comment. In your defence I must say that his comment is kind of misleading because his geometric demonstration is mathematic after all. I strongfully recommend that you view his videos. I did not watch it all (I am kind of lacking time at the moment) but the first tree parts were very good and will view the rest later tonight.

## Irving13

## antigoracle

They are the cosmic show and if only they could see themselves.

## Da Schneib

## Da Schneib

## Aligo

Aug 31, 2014## Da Schneib

I'd say the limits of relativity are pretty obvious, myself.

## Eddy Courant

## Benni

Albert Einstein 97

If we are to have in the universe an average density of matter which differs from zero, however small may be that difference, then the universe cannot be quasi-Euclidean. On the contrary, the results of calculation indicate that if matter be distributed uniformly, the universe would necessarily be spherical (or elliptical). Since in reality the detailed distribution of matter is not uniform, the real universe will deviate in individual parts from the spherical, i.e. the universe will be quasi-spherical. But it will be necessarily finite. In fact, the theory supplies us with a simple connection 1) between the space-expanse of the universe and the average density of matter in it."

As Relativity explains the field theory of gravity based on the curvature of spacetime, the end result is Einsteins conclusion regarding the structure of the Universe as quoted directly above from his GR thesis.

## antigoracle

Don't they?

For example when they go for a swim.

## swordsman

## Aligo

Aug 31, 2014## Da Schneib

## Da Schneib

Besides, that's caused by their interactions with the molecules in the water, so the photon that emerges is not the same photon that entered the water.

## Da Schneib

## Da Schneib

An exponent is not an eigenvalue. An eigenvalue is the amount by which an eigenvector must be multiplied in a mapping to yield the new eigenvector.

You are slinging words you don't understand around and pretending they "prove" your "theory." Scare quotes because you don't "prove" things in physics, only in math, and you don't have a theory, which has been tested by experiment, you have a conjecture that does not hold water when compared with reality.

## Benni

.....well aware of those conjectures, and when I read about anyone conjecturing that there is an "infinite" parameter anywhere in the universe, I say to them "Show me one".

.....Standard Model- would result in a perfectly spherical universe, but Einstein proposed a "quasi-spherical" universe to account for "lumpiness" (galactic clusters)

....but not flat.

......exactly right, the translation being that the universe may be much older than 13.6 Gyrs with such small curvature. That complex integral used on redshift calculators

will need to have the limits changed, and I think it's the James Webb telescope that will prove this.

## Da Schneib

## Benni

I'm not talking about "redshift". I'm talking about the the "integral" used to "calculate" redshift, it has a limit set far too low for the size of a positively curved universe. Ever played around with one of those internet redshift calculators? That's what I'm talking about.

## Whydening Gyre

Guess that depends on the "time zone" you're in...

That said, the "clock speed" is the same throughout...

## Mimath224

Didn't intend to suggest that I had a procedure just more of a modus p.p. thought. From a conventional point of view if the universe is expanding and photon v is max then photons enter the expansion before (slower) matter; but would that suggest photons create the expansion? Would that continue to ∞ ? Another point that I'd like help with is that space is not a vacuum but apparently full of energy (not to mention DE & DM) so would this constitute a 'medium' in which photon v would be slower than in a true vacuum? If that be the case then photons would 'experience' a finite period of travel.

## TimLong2001

## Reg Mundy

Or maybe expanding photons are just an example of the expansion of all matter?

## Reg Mundy

Very perceptive....

## Uncle Ira

So right now it is 6:42 p&m.

## AmritSorli

http://cosmology....Time.pdf

## Reg Mundy

## apostolvictor999

I know it is said something like: as the speed increases, you need more and more energy to move mass, toward infinite energy; so you need infinite energy to move to the speed of light.

Why is that? Because the speed of light is finite, not infinite, therefore the energy needed to reach it should be also finite.

Can you tell me were am I wrong?

## Jixo

Sep 03, 2014## mahi

Even if we observe a particle travelling faster than light, we take that as proof of time dilation delusion. So obviously no particle can travel faster than light.

http://debunkingr...y-mania/

## Jixo

Sep 03, 2014## mahi

As if our scientists have personally followed the photons all along, and closely watched them travelling in 'continuous paths' and not doing the weird jumps!!!

By the way Jixo, why isn't that a photon experience the above weird phenomena and do such weird jumps as it travels?

Without such dual standards, I am sure relativity and quantum physics won't survive.

## Da Schneib

## Da Schneib

We can never find out. ∞ is beyond the horizon.

contd

## Da Schneib

Good questions, Mimath.

## Da Schneib

## Da Schneib

Time and the three space dimensions are all symmetric; but the symmetry of the time dimension is not circular, like the space dimensions; it is hyperbolic. This is what SRT tells us.

Because mass increases with velocity, and acceleration decreases with mass.

The energy to reach it depends not on light but on matter, and matter increases its mass exponentially as speed approaches lightspeed.

## Whydening Gyre

You said way earlier in the thread;

"...the speed and the wavelength change, but the frequency does not."

Isn't wavelength the frequency?

(perhaps I'm "quantumizing" on a way too general level)

## Whydening Gyre

"...if you had a watch, you'd know it was night time. An' night time ain't NO time to be in this here neighborhood..."