Relativity discussion from “What is Time?” thread

[freeztar]

I am not an expert on red/blue shift anyway, tho I do know that the whole topic is presently being challenged by certain "Whackos" like Alton Arp. (So name-called by our dear Modest, tho Dr. Arp's credentials are quite impressive.)

See Halton Arp's discoveries about redshift

 

Gotta go.

Michael

 

Halton Arp has been covered thoroughly at Hypography. Do a search here for his name and redshift-z.

 

Basically, his photos do not suggest what he claims. From the link you give, the photos are completely unconvincing. Dr. Arp will need *a lot* more evidence to throw Astronomy on its head.

[modest]

Ok, the first example. A and B each have a gyroscope and circuitry to keep them parallel even though B continues to move in a straight line away in the direction of the arrow thus the distance between them increases.

 

I see.

 

Modest, in my opinion I think you are absolutely correct . The doppler shift experienced by B is due to it's changing frame of reference ( Delta t ) and links doppler shift to my hypothesized earlier posts suggesting that gravity and Inertia are also due to changing frames of reference.

 

Do you mean this:

We tend to think that velocity is the reason for relativity but that is not true. Acceleration is the reason for time dilation and length contraction.

 

In your first example, both classical doppler shift and time dilation cause a frequency shift. You could find the change in frequency by dividing the emitted frequency by 1-v/c (classical doppler shift) then dividing that answer by the Lorentz factor to account for time dilation. That would give you the observed frequency.

 

In the second example, there is no classical doppler shift because the distance between the two is always equal. The only frequency shift is from time dilation which you could again find from A's perspective by dividing the emitted frequency by the Lorentz factor.

 

Since time dilation has the same effect in both cases I don't see what you are meaning to convey. Could you explain your thinking in more detail?

 

~modest

[amrit]

Time is a mind frame through which we experience motion in timeless universe

 

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[Ben]

Brilliant. I fact so brilliant, I didn't understand. Care to explain your assertion to we Earthlings?

[Qfwfq]

Care to explain your assertion to we Earthlings?

Just a mathematical trick, a seldom-used alternative to distinguishing between covariant and contravariant components. Instead of muliplying [imath]a[/imath] times [imath]-b[/imath] you can get the same result multiplying [imath]ia[/imath] times [imath]ib[/imath], in both cases you get [imath]-ab[/imath].

 

These folks seem to think that this removes the distinction between spacelike and timelike intervals but I disagree; [imath]ds[/imath] still can have positive, negative or zero values...:shrug:

[Pyrotex]

The latest issue of Scientific American has an excellent article on What Is Time?

 

A lot of you guys have come close to the SA article conclusion, which basically is this:

 

[i hope I paraphrase this right] Space and Time are emergent phenomenon in the universe. At the subatomic quantum level, there may be no Space or Time at all. The manifestation of "raw" quantum matter/energy (which is actually neither) at the scale of the extremely small must interact with itself to form little clots (called by one scientist, "spinors", by other scientists, "strings") which are surrounded by fields. The mutual interaction of these fields actually generate a uniform super-field that we experience as "Space"; and generates a pattern of change-behavior that we experience as "Time".

 

Later in the article, they suggest that much progress has been made in showing that the math of "spinors" and "strings" can be equivalenced.

 

It's worth a read.

[Pyrotex]

The momentum four-vector is conserved. The clock that travels through the most space accumulates the least time. Acceleration is irrelevant and relative velocity can be arbitrarily small.

... Compare elapsed times. Elapsed times #2+#3 does not equal #1, the local stationary reference frame summation. The sum of #2+#3 elapsed time is about 4.5% that than of #1's accumulated elapsed time. The Twin (Triplets) Paradox obtains without any clock having been accelerated....

Damn, you're good.

 

Damn, I wish I had said that.

 

My hat is off to you, Velociclockmeister!