Does the force of Earth's gravity change over time

I have thought about this for some time and don't really have an explanation.

The dinosaurs were massive beast that could only have survived under weaker gravity conditions, IMO. With today's gravity, an elephant represents the maximum size of a land animal. Anything larger couldn't support its own weight unless supported by water.

How did long necked dinosaurs survive, did they have multiple hearts to pump blood to the brain at the end of that long neck? Seems to me the brain would have needed to be closer to the heart, if the heart was located in the body cavity.

One possible explanation is that the Earth was smaller than it is today and has been expanding like a balloon over the 100s of millions years since the dinosaurs roamed the Earth. The continents fit together perfectly when the Earth is shrunk to a smaller size. If this is a correct assumption then my question is, whats causing the expansion, energy from the Sun, unknown energy from inside the Earth?

There are petroglyphs of dinosaurs that were depicted indicating they were no larger than a big dog, so they may have been around up until recently or may still exist on a smaller scale but haven't been discovered. Perhaps dinosaurs have shrunk in correlation to Earths expanding mass.

a reply to: eManym

With today's gravity, an elephant represents the maximum size of a land animal.

How do you know this?

One possible explanation is that the Earth was smaller than it is today and has been expanding like a balloon over the 100s of millions years since the dinosaurs roamed the Earth.

Yeah. But there a lot of problems with that explanation.

There are petroglyphs of dinosaurs that were depicted indicating they were no larger than a big dog, so they may have been around up until recently or may still exist on a smaller scale but haven't been discovered.

Aside from that petroglyphs claim, you know that there were very many species of dinosaurs?

phenomena.nationalgeographic.com...

Gravity might have been been different but that doesn’t mean that dinoasaurs couldn’t have been larger than an elephant, if there is the space and big enough food sources there isn’t an upper limit on size.

I have pondered the same idea.
Is it possible that Earth has more mass and therefor more gravity than it did hundreds of millions of years ago?
Why are there no more 6' centipedes, dragonflies with 3' wing-spans, giant lizards?
Could collected space dust account for an increase in mass which would equal more gravity?

I always thought it was the higher oxygen content that allowed for the size some dinosaurs could get to.?

originally posted by: eManym
I have thought about this for some time and don't really have an explanation.

The dinosaurs were massive beast that could only have survived under weaker gravity conditions, IMO. With today's gravity, an elephant represents the maximum size of a land animal. Anything larger couldn't support its own weight unless supported by water.

How did long necked dinosaurs survive, did they have multiple hearts to pump blood to the brain at the end of that long neck? Seems to me the brain would have needed to be closer to the heart, if the heart was located in the body cavity.

How do giraffes survive? They have long necks, right?

One possible explanation is that the Earth was smaller than it is today and has been expanding like a balloon over the 100s of millions years since the dinosaurs roamed the Earth.

Maybe 100 years ago it might have been considered a possible explanation. Today there is an overwhelming amount of evidence contradicting it, coming from plate tectonics, and satellites making precision measurements of the Earth.

www.nasa.gov...

Since Charles Darwin's time, scientists have speculated that the solid Earth might be expanding or contracting. That was the prevailing belief, until scientists developed the theory of plate tectonics, which explained the large-scale motions of Earth's lithosphere, or outermost shell. Even with the acceptance of plate tectonics half a century ago, some Earth and space scientists have continued to speculate on Earth's possible expansion or contraction on various scientific grounds.

Now a new NASA study, published recently in Geophysical Research Letters, has essentially laid those speculations to rest. Using a cadre of space measurement tools and a new data calculation technique, the team detected no statistically significant expansion of the solid Earth.

The continents fit together perfectly when the Earth is shrunk to a smaller size.

No they don't. This video shows how badly that claim fails with respect to Alaska:

If this is a correct assumption then my question is, whats causing the expansion, energy from the Sun, unknown energy from inside the Earth?

It's not a correct assumption. See the video, Alaska doesn't fit.

There are petroglyphs of dinosaurs that were depicted indicating they were no larger than a big dog, so they may have been around up until recently or may still exist on a smaller scale but haven't been discovered. Perhaps dinosaurs have shrunk in correlation to Earths expanding mass.

Earth gains a tiny amount of mass from space debris such as dust and meteorites but since the Earth doesn't have a glass dome holding in the atmosphere like some people seem to think, some of the atmosphere leaks out into space, perhaps a little more mass than the incoming space debris, so the net effect is that the mass of the earth may be decreasing slightly but not by a significant amount.

Earth Loses 50,000 Tonnes of Mass Every Year

The net loss is about 0.000000000000001% every year, so it doesn’t account for much when compared to the total mass of the Earth

That amount of change won't have much effect on life forms, even over millions of years, because it's still a small percentage after multiplying by millions.

It would seem that gravity is proportionate to mass. So I doubt there's been much measurable difference ?

a reply to: vonclod

O2 levels weren't all that much higher for the dinosaurs than they are now.

That article I linked explains it quite well. Bottom line though, mammals are far different from dinosaurs. That's why they aren't as big. Nothing to do with gravity or O2.

a reply to: Phage

Ok, thanks for the info, I will check out the article.

a reply to: eManym

I thought dinos were big because of the oxygen levels were higher. I googled it and found this. Could be part of the reason but not all from some of the other articles. www.livescience.com... and this one www.sciencefocus.com...

It has to be...I mean there is no way that I weigh what I do.

To answer your first question, its the square - cube law. As an animal's size is scaled up in equal dimensions, an increase in the cross section of its muscles is a square of the scaling and the mass increases by the cube of the scaling. The elephant is the maximum size than an animal can get, around around 6 to 8 tons, without having severe respiratory and circulatory problems. It also would not be able to support its own weight.

Care to elucidate the problems with the expanding Earth hypothesis?

Many species of dinosaurs have existed and smaller ones are indicated in petroglyphes.

Pterodactyls were a successful flying creature that existed about 150 million years ago. They weighed between 300 to 400 pounds. How could they fly when today's birds have trouble getting off the ground at 25 pounds.

originally posted by: eManym
To answer your first question, its the square - cube law. As an animal's size is scaled up in equal dimensions, an increase in the cross section of its muscles is a square of the scaling and the mass increases by the cube of the scaling. The elephant is the maximum size than an animal can get, around around 6 to 8 tons, without having severe respiratory and circulatory problems. It also would not be able to support its own weight.

Care to elucidate the problems with the expanding Earth hypothesis?

Many species of dinosaurs have existed and smaller ones are indicated in petroglyphes.

Pterodactyls were a successful flying creature that existed about 150 million years ago. They weighed between 300 to 400 pounds. How could they fly when today's birds have trouble getting off the at 25 pounds.

A huge wingspan helps a lot.

a reply to: eManym

As an animal's size is scaled up in equal dimensions, an increase in the cross section of its muscles is a square of the scaling and the mass increases by the cube of the scaling.

Do you think sauropods were solid muscle and bone like a mammal?

Care to elucidate the problems with the expanding Earth hypothesis?

Mostly, gravity is proportional to mass. Explaining the increase in mass while the Earth got bigger is problematic. Unless you start arm waving about an internal sun and crap like that.

Many species of dinosaurs have existed and smaller ones are indicated in petroglyphes.

No they aren't. Though creationists like to think so.

They weighed between 300 to 400 pounds.

Even heavier, possibly. They had really big wings.

a reply to: Tarzan the apeman.

From the article Phage linked, the increased O2 did allow insects during one period get much larger, their systems for taking in O2 were not efficient, thus the 30% O2 at that time allowed for more growth.
The O2 levels during the time of some big dino's may of been close to what it is today.
The article implies the big dino's had less mass relative to animals today, lighter bones(like birds) among other things..that is my take from glossing over the link.

a reply to: vonclod
That is a good article. Interesting. Air sacs. Makes me wonder about birds and having hollow bones.

a reply to: Tarzan the apeman.

They do say birds are closely related to dino's

Many dinosaurs had hollow bones such as the Tyrannosaurus, it must have been a very slow mover and a large muscle mass as not to cause a bone fracture. Herbivores, like the Supersaurus, the largest dinosaur so far discovered, had marrow filled bones in the pelvic area. There must have been a large muscle mass and bone density, as well as lower gravity conditions, to support the mass of such a large creature. Also, to move its neck and legs.

a reply to: eManym

There must have been a large muscle mass and bone density to support the mass of such a large creature. Also, to move its neck and legs.

Yes. Large muscles, no doubt about that. But you seem to be relying on outdated ideas about dinosaur physiology. Among other things.

How much do you figure one of those big boys weighed? In today's gravity.

The dinosaurs depicted in petroglyhs were depicted as small in stature. Seems to me if they were seen as large than the petroglyphs would be much larger indicative of their size.

I am not relying on outdated information. Just because there is new data doesn't mean the old data is superseded by the new.

As for the pterdactyl argument, a 300 to 400 pound animal would need a 60 to 80 foot wingspan and an enormous amount of energy to get off the ground unless they stayed airborne for their lifetime.

I didn't imply an internal sun at the Earths core just some unknown process that may have the effect of increasing mass.