HST and 'dark matter' Options

[Guest_PhilCo126_*]

ASA Updates Plans for Hubble 'Ring Of Dark Matter' Briefing

GREENBELT, Md. - NASA will hold a media teleconference at 1 p.m. EDT on May 15 to discuss the strongest evidence to date that dark matter exists. This evidence was found in a ghostly ring of dark matter in the cluster CL0024+17, discovered using NASA's Hubble Space Telescope. The ring is the first detection of dark matter with a unique structure different from the distribution of both the galaxies and the hot gas in the cluster. The discovery will be featured in the June 20 issue of the Astrophysical Journal.

[djellison]

So it'snot a question about a bucket at all, it's just asking WHY F=MA

[Greg Hullender]

So it'snot a question about a bucket at all, it's just asking WHY F=MA

This has been a question for a long time. I remember my Physics professor at Caltech making a point of it when I was a freshman back in 1977.

When I was a kid, protons and neutrons were thought to be fundamenal particles, although there was a bewildering array of other, short-lived subatomic particles. It was exciting to witness the discoveries that replaced all that with the much more elegant system of quarks and leptons, and it's even exciting to think we may be witnessing another major refinement.

It'll be nice when someone has worked out an easier way to explain it to the educated layman. Meanwhile, I'm still waiting for someone to explain how they plan to test this hypothesis.

--Greg

[Marz]

This has been a question for a long time.

lol - who would've thought a spinning bucket is at the heart of modern physics?

I think the essence of the Bucket is to understand what aspects of gravity are mathematical abstractions or a natural phenomenon. From Greene's layman book "Fabric of the Cosmos" Chp 2, The Universe and the Bucket:

"If velocity is something that only makes sense by comparisons ... how is it that changes in velocity are somehow different, and don't also require comparisons to give them meaning? ... Could it be that there is some implicit or hidden comparison that is actually at work every time we refer to our experiences of accelerated motion? This is a central question .... it touches on the deepest issues surrounding the meaning of space and time."

Meanwhile... I'll have to decide what feels less silly:

Dark Matter (and perhaps Dark Energy) or holographic screens. Planetary geology is so lovingly concrete in comparison.

[AndyG]

lol - who would've thought a spinning bucket is at the heart of modern physics?

I prefer the late Douglas Adams' prescient insight into this. A nice cup of tea lies at the heart of Arthur Dent's well-being and, of course, stirring tea and then momentarily rotating the cup provides a demonstrably easier, tastier (and potentially less wet) appreciation of inertia and Mach's Principle.

Andy