### Prove that Hilbert Space is a Metric Space?

The question doesn't make sense, or alternatively it is true by definition. A Hilbert Space is a complete inner product space - complete in the metric induced by the norm defined by the inner product over the space. In other words an inner product space is a vector space with an inner product defined on it. An inner product then defines a norm on the space, and every norm on a space induces a metric…

### What is the price per pound of a metric ton?

That depends on what substance the dealer has a metric ton of. If it's a metric ton of air, the price is probably quite low, although they would probably not offer to deliver it. It it's a metric ton of water, the price is probably a bit higher, but still quite low, and they might include delivery. If it's a metric ton of gold, I would expect the price to be very high; but it…

### What is the difference between holes and electrons?

The modern answer to this question is discussed in my recent paper `What tells Gravity on the shape and size of an electron'' arXiv:1212.2920 Gravitational field of an electron, fixed by experimental values of its mass, spin, charge and magnetic moment, is given by the metric of Kerr-Newman (KN) solution. The spin of electron is very high and the black hole horizons disappear. So, it is over-rotating KN solution without horizons. Unexpectedly, this metric contains…

### What is the history of the SI base units?

It started more than 200 years ago, with the invention of the metric system. http://en.wikipedia.org/wiki/SI#History Answer In 1948, the General Conference of Weights and Measures (CGPM) charged an international committee, the CIPM*, to 'study the establishment of a complete set of rules for (metric) units of measurement'. The outcome of this study was a rational system of metric units termed 'SI'.

### What instrument measures metric length?

A metric ruler. A metric ruler or a metric tape measure. You can also use a meterstick. I'm pretty sure that would be a metric ruler A metric ruler. Rulers, metersticks, etc..... A metric ruler. The units of metric length are centimeters and millimeters. Since it's the metric system, 10 millimeters=1 centimeter.

### Difference between metric tonne and tonne?

A tonne is a metric unit of 1000kg and is the metric equivalent of a ton., ie a metric ton. A metric tonne is a tautological description of a tonne, ie the "metric" part is unnecessary as "tonne" is the [spelling of] "ton" in the metric system of units. (A "metric tonne" says a "metric metric ton" - just like a "pin number" is a "personal-identification-number number".) Or to put it another way, they are…

### What metric unit is used to measure a wrist watch?

A metric watch measures metric time, so instead of 24 hours per day in metric there are 10. There are 100 metric minutes to each metric hour so therefore there are 1000 metric minutes per day compared to 1440 minutes per day in our present system. There are 100 metric seconds to a metric minute, therefore there are 100,000 metric seconds to a day compared to 86,400 in our present system.